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  • Polymer and Materials Science  (7,082)
  • Industrial Chemistry  (835)
  • 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology
  • 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
  • 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
  • Wiley-Blackwell  (7,918)
  • Società Geologica Italiana  (6)
  • American Geophysical Union  (5)
  • Springer Berlin Heidelberg  (3)
  • Springer  (2)
  • 2010-2014  (17)
  • 1995-1999  (5,338)
  • 1975-1979  (2,579)
  • 2012  (17)
  • 1996  (5,338)
  • 1975  (2,579)
Collection
Keywords
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Years
  • 2010-2014  (17)
  • 1995-1999  (5,338)
  • 1975-1979  (2,579)
Year
  • 1
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    Crustal changes at Mt. Etna volcano accompanying the 2002–2003 eruption as inferred from a repeating earthquake analysis (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: In this work, waveform variations in repeating volcanotectonic earthquakes occurring from 2001–2009 in the northeastern flank of Mt. Etna were studied. Changes in waveform were found mainly during 2002–2003; and consisted of a decreasing similarity in the coda of events in earthquake families, as revealed by cross-correlation analysis, and delays, increasing proportionally to the lapse time, detected by coda wave interferometry. Such variations, mainly evident at stations located in the north-eastern flank of the volcano, were likely due to medium changes taking place within this region. Localized medium velocity decreases were inferred to occur in 2002–2003, followed by successive increases. The velocity decrease was interpreted as being caused by the opening or enlargement of cracks, produced by intruding magma bodies, intense ground deformation, and/ or VT earthquake activity that accompanied the 2002–2003 Mt. Etna eruption. On the other hand, subsequent velocity increases were interpreted as resulting from healing processes.
    Description: Published
    Description: L18311
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: coda wave interferometry ; Etna ; VT earthquakes ; Pernicana fault ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    Geometry and modeling of an active offshore thrust-related fold system: the Amendolara Ridge, Ionian Sea, southern Italy (2012)
    Società Geologica Italiana
    Details
    Publication Date: 2017-04-04
    Description: On the Ionian Sea coast of southern Italy, spanning the transition from the Calabrian Arc to the Apennines, NE-directed motion of the thin-skinned frontal thrust belt of the Apennines toward the Apulian foreland reportedly ceased during the Early-Middle Pleistocene. The submarine extension of the frontal thrust belt is represented by the Amendolara ridge, which stretches for over 80 km to the SE beneath the Taranto Gulf. High-resolution marine geophysical data collected on the Amendolara ridge during the TEATIOCA_2011 cruise provided unequivocal constraints to assert active fault-related fold growth. Single-channel seismic (sparker) and acoustic CHIRP profiles, corroborated by multibeam mapping and shallow coring, form the novel dataset to constrain the near-bottom evolution. The new data were benchmarked to the crustal geometry by means of interpretation of existing multichannel seismic profiles.
    Description: Published
    Description: Arcavacata di Rende (CS)
    Description: 3.2. Tettonica attiva
    Description: open
    Keywords: Active fault-propagation folds ; Blind faults ; Seismogenic sources ; Jonian Sea ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Extended abstract
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  • 3
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    Geological evolution of a complex basaltic stratovolcano: (2012)
    Società Geologica Italiana
    Details
    Publication Date: 2017-04-04
    Description: An updated geological evolution model is presented for the composite basaltic stratovolcano of Mount Etna. It was developed on the basis of the stratigraphic setting proposed in the new geological map that was constrained by 40Ar/39Ar age determinations. Unconformitybounded stratigraphy allows highlighting four main evolutionary phases of eruptive activity in the Etna region. The Basal Tholeiitic Supersynthem corresponds to a period, from about 500 to 330 ka, of scattered fissure-type eruptions occurring initially in the foredeep basin and then in a subaerial environment. From about 220 ka, an increase in the eruptive activity built a lava-shield during the Timpe Supersynthem. The central-type activity occurred at least 110 ka ago through the Valle del Bove Supersynthem. The earliest volcanic centres recognized are Tarderia, Rocche and Trifoglietto and later Monte Cerasa, Giannicola, Salifizio and Cuvigghiuni. During the Stratovolcano Supersynthem, from about 57 ka ago, the intense eruptive activity of Ellittico volcano formed a roughly 3600 m-high stratocone that expanded laterally, filling the Alcantara and Simeto paleovalleys. Finally, effusive activity of the last 15 ka built the Mongibello volcano. Its eruptive activity is mainly concentrated in three weakness zones in which the recurrent magma intrusion generates flank eruptions down to low altitude. The four main evolutionary phases may furnish constraints to future models on the origin of Etna volcano and help unravel the geodynamic puzzle of eastern Sicily.
    Description: Published
    Description: 306-317
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Mount Etna, geological evolution, stratigraphy, ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Geological map of Etna volcano, 1:50,000 scale (2012)
    Società Geologica Italiana
    Details
    Publication Date: 2017-04-04
    Description: The new geological map of Etna volcano at 1:50,000 scale represents a significant progress in the geological studies of this volcano over the last 30 years, coming after Waltershausen’s map published around the mid of 19th century, the first geological map of a large active volcano, and the ROMANO et alii (1979) map published about a century later, both at 1:50,000 scale. Lithostratigraphy was used for mapping volcanic units and then Unconformity Bounded Units were applied to group lithostratigraphic units into synthems. In addition, lithosomes were exploited to better represent the spatial localization of different eruptive centres according to their morphology. On the whole, we identified 27 lithostratigraphic units, grouped into 8 synthems, and 9 volcanoes. In detail, effusive and explosive deposits generated by each eruption of Mongibello and, partially, Ellittico volcanoes were mapped as flow rank. This stratigraphic framework represents the best synthesis of the geological evolution of Etna volcano using the main unconformities recognized within its complex volcanic succession. In addition, we constrain the Etna volcanic succession and its lithostratigraphic units chronologically by radioisotope age determinations. On the basis of the outlined synthemic units, it was possible to divide Etna’s volcanic succession into 4 supersynthems, which correspond to 4 well-defined and spatially localized phases. The detailed reconstruction of the past eruptive activity allowed compiling the most accurate dataset in particular of the Holocene eruptions of Etna volcano, which will enable significantly improving the volcanic hazard assessment, together with petrological interpretation of erupted magmas and geophysical modelling of the volcano plumbing system.
    Description: Published
    Description: 265-291
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: reserved
    Keywords: Mount Etna, geological map, basaltic composite ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
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    Flank instability structure of Mt. Etna inferred by a magnetotelluric survey (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: This paper presents a magnetotelluric (MT) survey of the unstable eastern flank of Mt. Etna. We take thirty soundings along two profiles oriented in the N-S and NW-SE directions, and from these data recover two 2D resistivity models of the subsurface. Both models reveal three major layers in a resistive-conductive-resistive sequence, the deepest extending to 14 km bsl. The shallow layer corresponds to the volcanic cover, and the intermediate conductive layer corresponds to underlying sediments segmented by faults. These two electrical units are cut by E-W-striking faults. The third layer (basement) is interpreted as mainly pertinent to the Apennine-Maghrebian Chain associated with SW-NE-striking regional faults. The detailed shapes of the resistivity profiles clearly show that the NE Rift is shallow-rooted ( 0–1 km bsl), thus presumably fed by lateral dikes from the central volcano conduit. The NW-SE profile suggests by a series of listric faults reaching up to 3 km bsl, then becoming almost horizontal. Toward the SE, the resistive basement dramatically dips (from 3 km to 10 km bsl), in correspondence with the Timpe Fault System. Several high-conductivity zones close to the main faults suggest the presence of hydrothermal activity and fluid circulation that could enhance flank instability. Our results provide new findings about the geometry of the unstable Etna flank and its relation to faults and subsurface structures.
    Description: This paper presents a magnetotelluric (MT) survey of the unstable eastern flank of Mt. Etna. We take thirty soundings along two profiles oriented in the N-S and NW-SE directions, and from these data recover two 2D resistivity models of the subsurface. Both models reveal three major layers in a resistive-conductive-resistive sequence, the deepest extending to 14 km bsl. The shallow layer corresponds to the volcanic cover, and the intermediate conductive layer corresponds to underlying sediments segmented by faults. These two electrical units are cut by E-W-striking faults. The third layer (basement) is interpreted as mainly pertinent to the Apennine-Maghrebian Chain associated with SW-NE-striking regional faults. The detailed shapes of the resistivity profiles clearly show that the NE Rift is shallow-rooted ( 0–1 km bsl), thus presumably fed by lateral dikes from the central volcano conduit. The NW-SE profile suggests by a series of listric faults reaching up to 3 km bsl, then becoming almost horizontal. Toward the SE, the resistive basement dramatically dips (from 3 km to 10 km bsl), in correspondence with the Timpe Fault System. Several high-conductivity zones close to the main faults suggest the presence of hydrothermal activity and fluid circulation that could enhance flank instability. Our results provide new findings about the geometry of the unstable Etna flank and its relation to faults and subsurface structures.
    Description: Published
    Description: B03216
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: JCR Journal
    Description: restricted
    Keywords: Etna ; magnetotelluric ; flank instability ; volcano ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.99. General or miscellaneous ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.05. Geomagnetism::04.05.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Spatial vent opening probability map of Etna volcano (Sicily, Italy) (2012)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2017-04-04
    Description: We produce a spatial probability map of vent opening (susceptibility map) at Etna, using a statistical analysis of structural features of flank eruptions of the last 2 ky. We exploit a detailed knowledge of the volcano structures, including the modalities of shallow magma transfer deriving from dike and dike-fed fissure eruptions analysis on historical eruptions. Assuming the location of future vents will have the same causal factors as the past eruptions, we converted the geological and structural data in distinct and weighted probability density functions, which were included in a non-homogeneous Poisson process to obtain the susceptibility map. The highest probability of new eruptive vents opening falls within a N-S aligned area passing through the Summit Craters down to about 2,000 ma.s.l. on the southern flank. Other zones of high probability follow the North-East, East-North-East, West, and South Rifts, the latter reaching low altitudes (∼400 m). Less susceptible areas are found around the faults cutting the upper portions of Etna, including the western portion of the Pernicana fault and the northern extent of the Ragalna fault. This structuralbased susceptibility map is a crucial step in forecasting lava flow hazards at Etna, providing a support tool for decision makers.
    Description: This study was performed with the financial support from the V3-LAVA project (DPC-INGV 2007–2009 contract).
    Description: Published
    Description: 2083–2094
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: restricted
    Keywords: Flank eruption ; Dike ; Volcano structure ; Susceptibility map ; Spatial clustering ; Back analysis ; 04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous ; 05. General::05.01. Computational geophysics::05.01.04. Statistical analysis ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    How do volcanic rift zones relate to flank instability? Evidence from collapsing rifts at Etna (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: Volcanic rift zones, characterized by repeated dike emplacements, are expected to delimit the upper portion of unstable flanks at basaltic edifices. We use nearly two decades of InSAR observations excluding wintertime acquisitions, to analyze the relationships between rift zones, dike emplacement and flank instability at Etna. The results highlight a general eastward shift of the volcano summit, including the northeast and south rifts. This steadystate eastward movement (1-2 cm/yr) is interrupted or even reversed during transient dike injections. Detailed analysis of the northeast rift shows that only during phases of dike injection, as in 2002, does the rift transiently becomes the upper border of the unstable flank. The flank's steady-state eastward movement is inferred to result from the interplay between magmatic activity, asymmetric topographic unbuttressing, and east-dipping detachment geometry at its base. This study documents the first evidence of steady-state volcano rift instability interrupted by transient dike injection at basaltic edifices.
    Description: Partially funded by INGV and the Italian DPC (DPC-INGV project V4 “Flank”). ERS and ENVISAT SAR data were provided by ESA through the Cat-1 project no. 4532 and the GEO Supersite initiative. The DEM was obtained from the SRTM archive. ERS-1/2 orbits are courtesy of the TU-Delft, The Netherlands. SAR data processing has been done at IREACNR, partially carried out under contract “Volcanic Risk System (SRV)” funded by the Italian Space Agency (ASI).
    Description: Published
    Description: L20311
    Description: 1.3. TTC - Sorveglianza geodetica delle aree vulcaniche attive
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: 1.10. TTC - Telerilevamento
    Description: 3.2. Tettonica attiva
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 4.3. TTC - Scenari di pericolosità vulcanica
    Description: JCR Journal
    Description: restricted
    Keywords: flank instability ; rift zones ; 04. Solid Earth::04.03. Geodesy::04.03.99. General or miscellaneous ; 04. Solid Earth::04.03. Geodesy::04.03.01. Crustal deformations ; 04. Solid Earth::04.03. Geodesy::04.03.06. Measurements and monitoring ; 04. Solid Earth::04.03. Geodesy::04.03.07. Satellite geodesy ; 04. Solid Earth::04.03. Geodesy::04.03.09. Instruments and techniques ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.06. Rheology, friction, and structure of fault zones ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.07. Tectonophysics::04.07.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.02. Geodynamics ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.08. Risk::05.08.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    Active extension in Val d’Agri area, Southern Apennines, Italy: implications for the geometry of the seismogenic belt. (2012)
    Wiley-Blackwell
    Details
    Publication Date: 2020-02-24
    Description: Integration of geologic, geomorphologic and seismologic data sets is used to reconstruct the recent tectonic evolution and active deformation pattern in the Val d’Agri area, located in the seismically active axial sector of the Southern Apennines (Italy). The western portion of the Apennines thrust belt has been affected by Pliocene–Quaternary extension during easterly roll-back and crustal delamination of the Adriatic slab. The bulk of Quaternary extension has been accommodated bySW-dipping oblique and normal faults,which have attained mature morphologic and structural features and, nowadays, separate mountain ranges from intermontane basins. However, in the present seismogenic belt, coseismic faulting locally occurs on NE-dipping structures, which might cut the inherited Pleistocene landscape. In theVal d’Agri basin, in spite of the large Early–Middle Pleistocene, displacement occurred on SW-dipping faults bordering its eastern flank, our investigations show that the recent basin evolution has been controlled by a NE-dipping fault system (Monti della Maddalena fault system, MMFS). This fault system cuts across the Monti della Maddalena range, west of the Agri valley and has not yet created an evident tectonic landscape. Notwithstanding, fault motion since the Middle Pleistocene might explain geomorphologic and hydrographic anomalies of the Agri river and its valley, where fault-controlled subsidence has captured the river course and produced an aggrading plain within a regional uplift context. Recent and ongoing motion is documented by fault scarplets in loose deposits, 14C ages of palaeosols and the spatial relation with low to moderate instrumental seismicity. Results from fault kinematic analysis are compatible with fault-plane solutions of local and regional seismic events, and indicate ∼NE–SW oriented extension. Recognition of the MMFS as a potential seismogenic fault increases the longitudinal extent of the NE-dipping, morphologically immature seismic sources in the Southern Apennines and argues against the range-bounding fault model for active extension in the region. The regional size of the NE-dipping seismogenic belt may result from impingement of a mantle wedge beneath the Apenninic chain and possibly track the external front of crustal delamination.
    Description: Published
    Description: 591-609
    Description: 3.2. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: active tectonics ; crustal deformation ; earthquakes ; geomorphology ; normal faulting ; Southern Italy ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Source mechanism of long-period events recorded by a high-density seismic network during the 2008 eruption on Mount Etna (2012)
    American Geophysical Union
    Details
    Publication Date: 2017-04-04
    Description: One hundred twenty-nine long-period (LP) events, divided into two families of similar events, were recorded by the 50 stations deployed on Mount Etna in the second half of June 2008. During this period lava was flowing from a lateral fracture after a summit Strombolian eruption. In order to understand the mechanisms of these events, we perform moment tensor inversions. Inversions are initially kept unconstrained to estimate the most likely mechanism. Numerical tests show that unconstrained inversion leads to reliable moment tensor solutions because of the close proximity of numerous stations to the source positions. However, single forces cannot be accurately determined as they are very sensitive to uncertainties in the velocity model. Constrained inversions for a crack, a pipe or an explosion then allow us to accurately determine the structural orientations of the source mechanisms. Both numerical tests and LP event inversions emphasise the importance of using stations located as close as possible to the source. Inversions for both families show mechanisms with a strong volumetric component. These events are most likely generated by cracks striking SW–NE for both families and dipping 70° SE (family 1) and 50° NW (family 2). For family 1 events, the crack geometry is nearly orthogonal to the dikelike structure along which events are located, while for family 2 the location gave two pipelike bodies that belong to the same plane as the crack mechanism. The orientations of the cracks are consistent with local tectonics, which shows a SW–NE weakness direction. The LP events appear to be a response to the lava fountain occurring on 10 May 2008 as opposed to the flank lava flow.
    Description: Published
    Description: B01304
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: 3.1. Fisica dei terremoti
    Description: JCR Journal
    Description: reserved
    Keywords: Etna Volcano ; long-period events ; source mechanism ; location ; plumbing systems ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
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    Slug Flow: Modeling in a Conduit and Associated Elastic Radiation (2012)
    Springer
    Details
    Publication Date: 2017-04-03
    Description: Among the eruptive styles, the Strombolian activity is one of the more easy to study because of its repetitive behavior. For this reason large amount of data can be comfortably collected. Strombolian volcanoes are like natural laborato- ries repeating the same experiment (individual explosions) many times each day. The development of quantitative models of eruptive dynamics is driven by the comparison of experimental ob- servations and synthetic data obtained through mathemat- ical, numerical or analogue modeling. Since Strombolian activity offers a profuse amount of interesting seismic signals, during the last decades there has been growing attention on seismological techniques aimed at retrieving the conduit geometry and the eruption dynamics from the seismological recordings. One of these techniques, the source function inversion, is able to re- trieve a summary of the forces acting on the volcanic con- duit during the VLP event generation [5]. The comparison of observed source functions with synthetic ones, obtained through numerical modeling, allow us to put constraints on the proposed models. Quantitative models, able to fit seismological observa- tions, are a powerful tool for interpreting seismic record- ings and therefor the seismological monitoring of active volcanoes.
    Description: Published
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: restricted
    Keywords: Strombolian activity ; Slug flow ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.01. Computational geophysics::05.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 11
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    Multiparametric Approach in Investigating Volcano-Hydrothermal Systems: the Case Study of Vulcano (Aeolian Islands, Italy) (2012)
    Springer
    Details
    Publication Date: 2017-04-04
    Description: Seismic activity, ground deformation, and soil and fumarole temperatures acquired during 2004–2007 at Vulcano (Aeolian Islands) are analysed and the time relations among the different time series are discussed. Changes in temperature of fumarolic gases took place during four ‘‘anomalous’’ periods (November 2004–March 2005; October 2005–February 2006; August–October 2006; July–December 2007) at the same time as an increasing number of volcano-seismic events. In particular, the temperatures at high temperature vents and at steam heated soil ranged in time from 180 to 440 C and from 20 to 90 C, respectively. The maximum daily number of volcano-seismic events was 57, reached during the second anomalous period. This seismicity, characterised by focal depth generally lower than 1 km below sea level (b.s.l.) and composed of different kinds of events associated to both resonance and shear failure processes, is related to the shallow dynamics of the hydrothermal system. During the analysed period, very few volcano-tectonic earthquakes took place and tilt recordings showed no sharp or important changes. In light of such observations, the increases in both temperature and volcano-seismic events number were associated to increases in the release of gas from a deep and stable magma body, without magma intrusions within the shallow hydrothermal system. Indeed, a greater release of gas from depth leads to increased fluid circulation, that can promote increases in volcano-seismic events number by both fracturing processes and resonance and vibration in cracks and conduits. The different trends observed in the measured geochemical and geophysical series during the anomalous periods can be due to either time changes in the medium permeability or a changing speed of gas release from a deep magma body. Finally, all the observed variations, together with the changing temporal distribution of the different seismic event kinds, suggest that the hydrothermal system at Vulcano can be considered unsteady and dynamic.
    Description: Published
    Description: 167–182
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: reserved
    Keywords: Volcano seismolog ; soil and fumarole temperatures ; tilt data ; hydrothermal system ; Vulcano Island ; volcanic unrest ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
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    Inferences on the source of long-period seismicity at Campi Flegrei from polarization analysis and reconstruction of the asymptotic dynamics (2012)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2017-04-04
    Description: In the present paper, we analyse long-period (LP) events and seismic noise recorded at Campi Flegrei during the uplift episode of 2004–2006. The results of a detailed polarization analysis indicate that the large number of LPs detected during the seismic crisis were accompanied by a sustained activity consisting of very low-energy volcanic signals. These weak volcanic signals, which are usually absent in ambient noise recorded in the studied area, and LP events have similar properties, namely they are radially polarized towards the same LP source. The large dataset analysed allows us to study the statistics of the polarization, leading to the extraction of the average properties of the volcanic signals. An estimate of the complexity of the system can be provided by the degrees of freedom necessary to describe the asymptotic dynamics in a reconstructed phase space. This analysis shows that both LPs and low-energy signals can be described by a low-dimensional dynamical system, while ambient noise unrelated to volcanic activity is higher dimensional. Based on these observations, we interpret the phenomena observed during the seismic crisis in the framework of the theory of self-oscillating systems, in which LPs and low-energy signals represent self-oscillations generated by a persistent hydrothermal source.
    Description: Published
    Description: 1537-1551
    Description: 1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
    Description: JCR Journal
    Description: restricted
    Keywords: Campi Flegrei, Long-period events, Self-sustained oscillations ; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 13
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    Morphometric analysis in the offshore of the southern Taranto Gulf: unveiling the structures controlling the Late Pleistocene-Holocene bathymetric evolution (2012)
    Società Geologica Italiana
    Details
    Publication Date: 2017-04-04
    Description: The present study is focused on a morphometric analysis of high resolution multibeam data (10m, 5m and, locally, 2m resolution), that were acquired during the oceanographic TEATIOCA 2011 campaign along a sector of the Ionian margin of northern Calabria. The integration of morphometric analysis with sparker and chirp data allowed to unveil basic but robust information about: 1. hierarchy of the fault systems controlling the bathymetric evolution; 2. the interplay between tectonic and erosional processes in sea-floor modeling; 3. uplift rates; 4. tilting processes.
    Description: Published
    Description: Arcavacata di Rende (CS)
    Description: 3.2. Tettonica attiva
    Description: open
    Keywords: fault modeling ; erosional marine terraces ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.04. Marine geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Extended abstract
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  • 14
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    Deformed Pleistocene marine terraces along the Ionian sea margin of southern Italy: Unveiling blind fault-related folds contribution to coastal uplift (2012)
    Società Geologica Italiana
    Details
    Publication Date: 2017-04-04
    Description: Morphotectonic analysis and fault numeric modeling of uplifted marine terraces along the southern half of the Taranto Gulf , between the Sibari and San Nicola plains (Fig. 1), allow us to place quantitative constraints on Middle Pleistocene-Holocene deformation in the Southern Apennines.
    Description: Published
    Description: Arcavacata di Rende (CS)
    Description: 3.2. Tettonica attiva
    Description: open
    Keywords: Marine terraces ; Regional uplift ; Fault propagation folds ; Fault modeling ; 04. Solid Earth::04.04. Geology::04.04.01. Earthquake geology and paleoseismology ; 04. Solid Earth::04.04. Geology::04.04.02. Geochronology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Extended abstract
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  • 15
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    Correlation of welded ignimbrites on Pantelleria (Strait of Sicily) using paleomagnetism (2012)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2017-10-06
    Description: Although the oldest volcanic rocks exposed at Pantelleria (Strait of Sicily) are older than 300 ka, most of the island is covered by the 45–50 ka Green Tuff ignimbrite, thought to be related to the Cinque Denti caldera, and younger lavas and scoria cones. Pre-50 ka rocks (predominantly rheomorphic ignimbrites) are exposed at isolated sea cliffs, and their stratigraphy and chronology are not completely resolved. Based on volcanic stratigraphy and K/Ar dating, it has been proposed that the older La Vecchia caldera is related to ignimbrite Q (114 ka), and that ignimbrites F, D, and Z (106, 94, and 79 ka, respectively) were erupted after caldera formation. We report here the paleomagnetic directions obtained from 23 sites in ignimbrite P (133 ka) and four younger ignimbrites, and from an uncorrelated (and loosely dated) welded lithic breccia thought to record a caldera-forming eruption. The paleosecular variation of the geomagnetic field recorded by ignimbrites is used as correlative tool, with an estimated time resolution in the order of 100 years. We find that ignimbrites D and Z correspond, in good agreement with recent Ar/Ar ages constraining the D/Z eruption to 87 ka. The welded lithic breccia correlates with a thinner breccia lying just below ignimbrite P at another locality, implying that collapse of the La Vecchia caldera took place at ~130–160 ka. This caldera was subsequently buried by ignimbrites P, Q, F, and D/Z. Paleomagnetic data also show that the northern caldera margin underwent a ~10° west–northwest (outwards) tilting after emplacement of ignimbrite P, possibly recording magma resurgence in the crust.
    Description: Published
    Description: 341-357
    Description: 1V. Storia eruttiva
    Description: JCR Journal
    Description: restricted
    Keywords: Pantelleria ; Ignimbrite ; Caldera formation ; Paleomagnetism ; Paleosecular variation of the geomagnetic field ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 04. Solid Earth::04.04. Geology::04.04.08. Sediments: dating, processes, transport ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.05. Geomagnetism::04.05.99. General or miscellaneous ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 04. Solid Earth::04.05. Geomagnetism::04.05.03. Global and regional models ; 04. Solid Earth::04.05. Geomagnetism::04.05.06. Paleomagnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.07. Rock magnetism ; 04. Solid Earth::04.05. Geomagnetism::04.05.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
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    Erosion of the continental lithosphere at the cusps of the Calabrian arc: Evidence fromSreceiver functions analysis (2012)
    American Geophysical Union
    Details
    Publication Date: 2022-05-04
    Description: Mediterranean tectonics has been characterized by an irregular, complex temporal evolution with episodic rollback and retreat of the subducted plate followed by period of slow trench-migration. To provide insight into the geodynamics of the Calabrian arc, we image the characteristics and lithospheric structure of the convergent, Apulian and Hyblean forelands at the cusps of the arc. Specifically we investigate the crustal and lithospheric thicknesses using teleseismic S-to-p converted phases, applied to the Adria-Africa plate margin for the first time. We find that the Moho in the Apulian foreland is nearly flat at ∼30 km depth, consistent with previous P receiver functions results, and that the Hyblean crustal thickness is more complex, which can be understood in terms of the nature of the individual pieces of carbonate platform and pelagic sediments that make up the Hyblean platform. The lithospheric thicknesses range between 70–120 km beneath Apulia and 70–90 km beneath Sicily. The lithosphere of the forelands at each end of the Calabrian arc are continental in nature, buoyant compared to the subducting oceanic lithosphere and have previously been interpreted as mostly undeformed carbonate platforms. Our receiver function images also show evidence of lithospheric erosion and thinning close to Mt. Etna and Mt. Vulture, two volcanoes which have been associated with asthenospheric upwelling and mantle flow around of the sides the slab. We suggest that as the continental lithosphere resists being subducted it is being thermo-mechanically modified by toroidal flow around the edges of the subducting oceanic lithosphere of the Calabrian arc.
    Description: Published
    Description: L23301
    Description: JCR Journal
    Description: restricted
    Keywords: continental lithosphere ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    New insights on the Holocene marine transgression in the Bahía Camarones (Chubut, Argentina) (2012)
    Società Geologica Italiana
    Details
    Publication Date: 2022-06-10
    Description: The stratigraphic reconstruction of the northern sector of the Bahía Camarones (Chubut, Argentina) allowed to improve our understanding of the Holocene marine transgression in the area. The first phase of the maximum of the transgression, is interpreted as dominated by the high rate of eustatic rise of sea level until ca. 6-7 ka BP possibly associated to sedimentary starvation as suggested by fossil accumulation. After this first phase, the general trend indicates a progressive fall of the relative sea level after the Middle Holocene high stand as documented in other parts of south America Atlantic coast. Our data, coupled with the robust radiocarbon data set available for the area from literature, indicate three main local steps of coastal aggradation between ca. 6600 and 5400 yr BP (ca. 7000-5600 yr cal BP), ca. 3300 and 2000 yr BP (ca. 3100-1700 yr cal BP), and ca. 1300-500 yr BP (ca. 1000-300 yr cal BP). A significant age gap in coastal aggradation is present between ca. 5300 and 4400 yr BP (ca. 5600-4500 yr cal BP), and perhaps between ca 2000 and 1300 yr BP (ca. 1700-1000 yr cal BP). These can be linked to phases of local sea level fall and/or phases of sedimentary starvation and/or changes in drift transport which can have produced local coastal cannibalization. However, no conclusive data can be advanced. Data obtained from careful measurements of sea level markers represented by the top of marsh and fluvial terraces indicate lower values for the sea level estimation compared with the data set previously proposed for the area. This stigmatizes the fact that field-oriented works are still the priority in the Patagonia coast along with accurate age measurement, especially for obtaining the fundamental information we need for predicting the environmental impact, in these coastal areas, from accelerate sea level rise as effect of global warming.
    Description: Published
    Description: 19-31
    Description: 1.10. TTC - Telerilevamento
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: reserved
    Keywords: Relative sea level ; sea level markers ; Patagonia ; Holocene ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology ; 04. Solid Earth::04.04. Geology::04.04.02. Geochronology ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
    Electronic Resource
    Electronic Resource
    Fundamental properties of fluoropolyether-based resins and related coatings (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 236 (1996), S. 111-127 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Neuartige Fluoropolyether-Polyol-Harze, die mit konventionellen Härtern wie Polyisocyanaten oder Melaminen aushärtbar sind, wurden hergestellt. Zunächst wurden oligomere NCO-terminierte Prepolymere durch Addition von Fluorpolyether-Makrodiolen unterschiedlicher Molekulargewichte an Isophorondiisocyanate erhalten. Durch die Reaktion dieser Prepolymeren mit Trimethylolpropan wurden endständige Hydroxygruppen eingeführt. Die Viskosität von Lösungen dieser Harze wurde bei unterschiedlichen Konzentrationen (Massenbruch 0,4-0,8) und Temperaturen (25°C-65°C) gemessen. Die erhaltenen Werte wurden auf der Basis der Erickson-Gleichung (Konzentrationsabhängigkeit von η) und unter Berücksichtigung des WLF-und des Arrhenius-Modells (Temperaturabhängigkeit von η) diskutiert. Das thermische Verhalten der Harze und von ausgehärteten Filmen wurde mit DSC bestimmt. Dabei wurden zwei Glasübergange beobachtet, die den separierten fluorhaltigen und nicht-fluorhaltigen Phasen zugeordnet werden können. Die Analyse des Zugverhaltens der Filme zeigte besonders bei den mit Isocyanat gehärteten Proben ein ausgeprägtes hart-plastisches Verhalten. Diese Werkstoffe erscheinen für die Anwendung als hoch-wertige, dauerfeste und klare Beschichtungen geeignet.
    Notes: New fluoropolyether polyolic resins are presented suitable to be cured with conventional hardeners as polyisocyanates or melamines. These resins are prepared by addition of fluoropolyether macrodiols (Fomblin® ZDOLTX) of various molecular weights to isophorone diisocyanate (IPDI) to give oligomeric NCO-terminated prepolymers. The final hydroxy functionality is obtained by the reaction of those prepolymers with trimethylolpropane (TMP). The viscosity of the resins is measured at various concentrations (weight fraction 0.8 - 0.4) and temperatures (T = 25-65°C). The results are discussed in terms of the Erickson equation (η vs. concentration) and using the WLF and Arrhenius models (η vs. T). The thermal behavior is studied by DSC for both the resins and cured films indicating the presence of two Tgs, corresponding to the segregated fluorinated and hydrogenated phases, the former particularly evident with the highest molecular weights of the fluorinated macromer. Tensile curves of selfsupported films are then analyzed showing an evident tough-plastic behavior especially for the isocyanate-cured films. The application of such materials as high-durability clear coats is finally proposed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052360109
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  • 19
    Electronic Resource
    Electronic Resource
    Modification of melamine-formaldehyde moulding compounds with epoxy resins (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 237 (1996), S. 1-44 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zur Verbesserung der Maßhaltigkeit und der Zähigkeit von gehärteten Melamin-Formaldehyd-Harz-Formmassen (MF) wurden teilverträgliche, methylolgruppenhaltige Epoxidharze (EP) auf Bisphenol A-Basis hergestellt und charakterisiert. Die Vernetzung solcher Epoxyresolharze durch 2-Ethyl-4-methylimidazol in Gegenwart von MF-Harz wurde untersucht. Spritzgepreßte Probekörper zeigen eine Zweiphasenstruktur; die EP-Phase kann als Wirt für carboxy-funktionalisierte, oligomere NBR-Kautschuke (CTBNX) dienen, die für sich allein in MF-Harzen nicht wirksam sind. Unter der Voraussetzung von kovalenten Bindungen in der Phasengrenzfläche kann durch den Zusatz von 0,5 bis 4 Gew.-% CTBNX zur MF-Formmasse bei EP-Anteilen bis 20 Gew.-% eine 50 bis 100proz. Steigerung von Bruchdehnung und Schlagzähigkeit erreicht werden, ohne daß Steifigkeit und Wärmeformbeständigkeit wesentlich abfallen. Bei moderaten EP/CTBNX-Gehalten wird zusätzlich die Nachschwindung von MF-Formteilen vermindert.
    Notes: In order to improve dimension stability and toughness of melamine formaldehyde moulding materials (MF), compatible bisphenol A epoxy resins (EP) with additional methylol groups were synthesized and characterized. Crosslinking of those epoxyresol resins with 2-ethyl-4-methylimidazole in the presence of MF resin was investigated. Transfer-moulded specimens revealed a two-phase morphology in which the EP phase is used as a host for modification with carboxylic functionalized oligomeric NBR rubber (CTBNX), which is not effective in MF moulding materials alone. The addition of 0.5 - 4 wt.-% CTBNX to the MF moulding materials at an epoxy content of maximum 20 wt.-% results in 50-100 % increase of elasticity and toughness without serious decrease in stiffness and heat deflection temperature, provided that covalent interfacial bonds exist. In addition, the post-shrinkage of MF parts decreases if a moderate EP/CTBNX content is introduced.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052370101
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  • 20
    Electronic Resource
    Electronic Resource
    New poly(vinyl chloride) blends, IIIPart II cf.5.. Physico-mechanical properties (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 238 (1996), S. 11-30 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der gleichzeitige Einfluß des Verhältnisses von Fließhilfsmittel (Paraloid K 120N), Rußart und Schlagzähmodifikator (CPE 3615 und Kane Ace B56 A) auf die wichtigsten physiko-mechanischen Eigenschaften unplastifizierter PVC-Mischungen wurde studiert.Die erhaltenen Resultate wurden mathematisch verarbeitet und graphisch als Funktionsflächen dargestellt. Bemerkenswert ist, daß die Einführung von 2,5 und 5 Teilen Ruß eine Verbesserung der physico-mechanischen Eigenschaften ermöglicht. Dieses Resultat ist durch die Anwesenheit der Schlagzäh- und Fließmodifikatoren zu erklären.
    Notes: The concurrent influence of the processing aid (Paraloid K 120N) and the carbon black ratio, as well as the nature and the ratio of the impact modifier (CPE 3615 and Kane Ace B56 A) on the main physico-mechanical characteristics of the poly(vinyl chloride)-based unplasticized mixtures have been studied. The results obtained, processed mathematically and plotted graphically in the form of response surfaces, evidenced that the improvement of certain physico-mechanical properties becomes possible by the introduction of 2.5 parts and 5.0 parts carbon black into these compounds. This is due to the introduction of impact modifiers and processing aids into the mixtures.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052380102
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  • 21
    Electronic Resource
    Electronic Resource
    New polyhydrazides and poly(1,3,4-oxadiazole)s containing pendent phenoxy groups (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 238 (1996), S. 63-71 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe neuartiger Polyhydrazide mit endständigen Phenoxygruppen wurde aus äquimolaren Anteilen von Dicarbonsäuredichloriden und Phenoxyterephthalsäuredihydrazid durch Lösungspolykondensation in N-Methyl-2-pyrrolidinon (NMP) bei niedriger Temperatur hergestellt. Durch thermische Cyclisierung der Polyhydrazide wurden die entsprehchenden Poly(1,3,4-oxadiazol)e mit endständigen Phenoxygruppen erhalten. Die Polymeren wurden durch Viskosimetrie, Löslichkeitsuntersuchungen, IR-Spektroskopie, Differentialkalorimetrie und Thermogravimetrie charakterisiert.
    Notes: A series of new polyhydrazides containing pendent phenoxy groups has been synthesized by low-temperature solution polycondensation of equimolar amounts of diacid dichlorides and 2-phenoxyterephthalic dihydrazide in N-methyl-2-pyrrolidi-none (NMP). The thermal cyclization of the polyhydrazides gave the corresponding poly(1,3,4-oxadiazole)s containing pendent phenoxy groups. The polymers were characterized by viscometry, solubility measurements, IR spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052380106
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  • 22
    Electronic Resource
    Electronic Resource
    Effect of electron beam radiation on mechanical and electrical properties of poly(ethylene-co-vinyl acetate) (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 238 (1996), S. 105-117 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Ethylen-Vinylacetat-Copolymeres (EVA) mit 12% Vinylacetat-Gehalt wurde mit Trimethylolpropantrimethacrylat (TMPTMA) als Sensibilisator mit Elektronen bestrahlt. Die mechanischen und elektrischen Eigenschaften der bestrahlten Copolymerproben wurden untersucht. Die Resultate zeigen, daß sich Zugfestigkeit und Bruchdehnung zunächst mit zunehmender Strahlungsdosis verbessern und bei Überschreiten einer optimalen Strahlungsdosis und Sensibilisatorkonzentration wieder verschlechtern. Durch die Bestrahlung wird eine Vernetzung des Polymeren ausgelöst, die auf den sich mit der Strahlungsdosis erhöhenden Gelanteil zurückgeführt wird. Im Vergleich mit den Originalproben nehmen sowohl die Dielektrizitätskonstante als auch der dielektrische Verlustfaktor durch die Elektronenbestrahlung ab.
    Notes: Ethylene-vinyl acetate (EVA) copolymer (12% vinyl acetate content) is subjected to electron beam irradiation using trimethylolpropane trimethacrylate (TMPTMA) as a radiation sensitizer. Mechanical and electrical studies of these irradiated samples show that the strength properties (tensile strength, elongation at break) are increased with radiation dosage up to an optimum radiation dose and sensitizer level above which the properties begin to deteriorate. Crosslinking of the polymer takes place on irradiation which is attributed to an increased gel content with increasing radiation dose. Compared to the original samples both dielectric constant and dielectric loss factor decrease for samples subjected to irradiation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052380110
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  • 23
    Electronic Resource
    Electronic Resource
    Homogeneous synthesis of cellulose p-toluenesulfonates in N,N-dimethylacetamide/LiCl solvent system (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 238 (1996), S. 143-163 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Cellulose-p-toluolsulfonsäureester (Cellulosetosylate) lassen sich durch homogene Umsetzung von Cellulose in einer Lösung aus N,N-Dimethylacetamid und LiCl mit Tosylchlorid (Tos-Cl) und Triethylamin in 24 h bei 8°C in hoher Ausbeute und mit minimalem Einbau von Chlordesoxy-Gruppen herstellen. Die unterschiedlichen Celluloseausgangsmaterialien hatten durchschnittliche Polymerisationsgrade von 280 bis 5100. Die Produkte wurden mit Elementaranalyse, 13C-NMR- und FTIR-Spektroskopie und durch Bestimmung der Grenzviskositäten charakterisiert. Die Erhöhung des Molverhältnisses Tos-Cl/Anhydroglucose-Einheit (AGU) von 0.6 auf 9.0 führte zu einem Anstieg des Substitutionsgrades (DS) von 0.4 bis auf einen Maximalwert von 2.3. Die Cellulosetosylate sind in herkömmlichen organischen Lösungsmitteln wie Dimethylsulfoxid (im gesamten DS Bereich) und in N,N-Dimethylacetamid, N,N-Dimethylformamid, Aceton, Tetrahydrofuran und Trichlormethan (in Abhängigkeit von DS) löslich. Durch 13C-NMR-Spektroskopie wurde nachgewiesen, daß die Tosylierung am O-6 Atom der AGU schneller als an den O-2/3 Atomen erfolgt. Die Analyse der korrespondierenden Ioddesoxycellulosen, die durch Umsetzung mit NaI in Acetylaceton synthetisiert wurden, bestätigte dies zusätzlich. Darüber hinaus wurden wichtige Eigenschaften der Cellulosetosylate wie die Stabilität gegenüber Alkali und thermischer Beanspruchung untersucht.
    Notes: Pure cellulose p-toluenesulfonates (tosylates) with an insignificant formation of chlorodeoxy groups were prepared by reacting cellulose dissolved in a solution of N,N-dimethylacetamide and LiCI with tosylchloride (Tos-CI) in the presence of triethylamine within 24 h at 8°C. Various cellulosic starting materials with a degree of polymerization from 280 to 5 100 were used. The samples obtained were characterized by means of elemental analysis, FTIR and 13C NMR spectroscopy, and their intrinsic viscosities. The rise of the molar ratio of Tos-CI/anhydroglucose unit (AGU) from 0.6 to 9.0 leads to an increase in the degree of substitution (DS) from 0.4 up to a maximum value of 2.3. The cellulose tosylates are readily soluble in common organic solvents like dimethyl sulfoxide (within the whole DS range) and in N,N-dimethylacetamide, N,N-dimethylformamide, acetone, tetrahydrofuran and trichloromethane depending on DS. As revealed by 13C NMR spectroscopy a faster tosylation takes place at the O-6 atom of AGU compared with the O-2/3 atoms. This was additionally confirmed by analysis of the corresponding iododeoxy celluloses synthesized with NaI in acetylacetone. Furthermore, some important properties as stability against alkaline and heat were studied as well.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052380113
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  • 24
    Electronic Resource
    Electronic Resource
    Coating of carbon-fiber surface by silicon carbide via sol-gel mixtures of tetraethyl orthosilicate and phenolic resin (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 27-32 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Herstellung einer SiC-Oberfläche auf Kohlefasern unter Verwendung einer Sol-Gel-Mischung von Tetraethylorthosilikat (TEOS) und Phenolharz wurde untersucht. FTIR- und SEM-Untersuchungen zeigten, daß die SiC-Oberfläche durch carbothermische Reduktion der Sol-Gel-Mischung bei 1 420°C innerhalb von 15-20 min in einer Argon-Atmosphäre gebildet werden kann. Mittels TGA konnte gezeigt werden, daß die SiC-Beschichtung die thermo-oxidative Stabilität der Kohlefasern erhöht. Bei der erreichten SiC-Schichtdicke von 0,47 μm, bei einem C/Si-Verhältnis von 4, zeigt sich keine Beeinflussung der mechanischen Stabilität der Kohlefasern.
    Notes: The preparation of a SiC coating on a carbon fiber surface using a sol-gel mixture of tetraethyl orthosilicat (TEOS) and phenolic resin was studied. FTIR and SEM investigations indicated that the SiC coating can be formed by carbothermal reduction of the sol-gel mixture at 1420°C for 15-20 min in an argon atmosphere. TGA of the coated fiber was also performed, showing that the SiC coating improves the thermooxidative stability of the carbon fiber. With the thickness of the obtained coating of 0.47 μm using a C/Si ratio of 4, this treatment does not affect the carbon fiber strength.
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    Adhesive properties of some pressure-sensitive adhesive agents containing oligomer additives (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 55-62 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Diese Mitteilung behandelt den Einfluß von oligomeren Polypropylen- und Polybutylenölen mit unterschiedlichem Molekulargewicht auf die adhäsiven Eigenschaften von ataktischem Polypropylen (aPP) und dessen Mischungen mit einem Styrol-Ethylhexylacrylat-Copolymeren. Die mechanische Adhäsionsarbeit Am von Mischungen, die ataktisches Polypropylen und das Oligomere enthalten, steigt mit dem Molekulargewicht des Oligomeren, was im Fall des Propylenöls signifikanter ist. Im Fall der ternären Mischungen des ataktischen Polypropylens mit dem Styrol-Ethylhexylacrylat-Copolymeren und Oligomeren wird ein Adhäsions-Maximum beobachtet, wenn der Gehalt an Styrol-Ethylhexylacrylat-Copolymeren in der Mischung ungefähr 30 Gew.-% erreicht. Wenn kein Oligomeres in der Mischung vorhanden ist, kann man bei dieser Zusammensetzung ein Adhäsions-Minimum beobachten, was auf die Unverträglichkeit der übrigen Komponenten zurückzuführen ist.
    Notes: This paper deals with the influence of oligomers, namely propylene oil and butylene oil, of different molecular weight on the adhesive properties of atactic polypropylene (aPP) and its mixtures with styrene-2-ethylhexyl acrylate (S-EHA) copolymer. The mechanical work of adhesion Am of the mixture containing atactic polypropylene and oligomer increases with the molecular weight of the oligomer, which was more significant in the case of propylene oil. For ternary mixtures aPP-S-EHA copolymer/oligomer a maximum of adhesion can be observed if the content of the S-EHA copolymer in the mixture reaches about 30 mass-%. In the absence of oligomers in the mixture a minimum of adhesion can be observed for this composition, which can be attributed to the incompatibility of the remaining components.
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    Untersuchungen zur synthese von poly(butadien-co-propylenoxid) mit einem ziegler-natta-titankatalysatorsystem (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 107-119 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: After comparison of three catalyst systems, i.e. [Nd(Oct)3/Al2Cl3ET3/Al(i-But)3, Ni(Oct)2/BF3OEt2/AlEt3 and Al(i-But)3/I2/TiCl4] the titanium catalyst system was used for the copolymerization of 1,3-butadiene with propylene oxide. The effects of monomer ratio on copolymer composition, conversion, microstructure, molar mass and molar mass distribution as well as of time of polymerization and of the aluminium/titanium ratio were evaluted. The copolymerization parameters were determined according to Kelen-Tüdős as rbutadiene = 0,9 and rpropylene oxide = 3,9. Copolymerization was confirmed by 13C NMR spectroscopy and extract evaluation combined with 1H NMR spectroscopy.
    Notes: Für die Copolymerisation von 1,3-Butadien mit Propylenoxid wurde nach dem Vergleich der drei Katalysatorsysteme Nd(Oct)3/Al2Cl3ET3/Al(i-But)3, Ni(Oct)2/ BF3OEt2/AlEt3 und Al(i-But)3/I2/TiCl4 das Titankatalysatorsystem eingesetzt. Neben dem Einfluß der Monomerzusammensetzung auf den Umsatz, die Microstruktur, die Copolymerzusammensetzung, die Molmassen sowie die Molmassenverteilungen wurden auch die Polymerisationszeit und das Aluminium/Titan-Verhältnis untersucht. Die Copolymerisationsparameter wurden nach Kelen-Tüdős zu rButadien = 0,9 und rPropylenoxid = 3,9 bestimmt. Der Copolymernachweis erfolgte über 13C-NMR-Spektroskopie und Extraktionsuntersuchungen in Verbindung mit 1H-NMR-Spektroskopie.
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    Phosphorus-containing polyurethanes based on bisphenol A via N-alkylation (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 191-199 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Phosphorhaltige Polyurethane (PU-P) auf der Basis von Bisphenol A wurden durch N-Alkylierung hergestellt und mittels IR- und 1H NMR-Spektroskopie charakterisiert. Physikalische und thermische Eigenschaften dieser Polyurethane wurden mittels Differentialkalorimetrie, Thermogravimetrie, Röntgenbeugung und Untersuchungen der Löslichkeit, der Feuerbeständigkeit (Sauerstoffindex, LOI) und der reduzierten Viskosität bestimmt. Die Glastemperaturen der N-alkylierten Polymeren sanken von 120°C für das Ausgangspolymere bis auf 29°C für das N-alkylierte Polyurethan mit 2 Gew.-% Phosphor. Die Viskosität der N-alkylierten Polyurethane nahm von 0,36 dL g-1 auf 0,24 dL g-1 ab. Die phosphorhaltigen Polyurethane besitzen eine geringere thermische Stabilität und bessere Löslichkeit sowie höhere Feuerbeständlgkeit als das Ausgangspolymere. Die Röntgenstreuexperimente ergaben, daß ein erhöhter Phosphorgehalt der Polyurethane die Kristallinität herabsetzt.
    Notes: Phosporus-containing polyurethanes (PU-P) based on bisphenol A were prepared by N-alkylation. The structures of N-alkylated polyurethanes were characterized by IR and 1H NMR spectra. Physical and thermal properties of the phosphorus-containing polyurethanes were investigated with differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction, tests of solubility, limiting oxygen index (LOI) and reduced viscosity. Tg of the N-alkylated polymers decreased from 120°C for the starting polymer to 29°C of the 2.0 wt.-% phosphorus-containing polyurethanes. The viscosity of N-alkylated polyurethanes also decreased from 0.36 dL g-1 to 0.24 dL g-1. The thermal stability of polyurethanes decreased on the introduction of phosphorus groups. The LOI values of polyurethanes showed that fire resistance of phosphorus-containing polyurethanes was enhanced. X-ray diffraction measurements showed that the increased phosphorus content was accompanied by decreased crystallinity of the polyurethanes. The solubility of PU-P was improved.
    Additional Material: 2 Ill.
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    Are cured thermoset resins inhomogeneous?Lecture presented at International Symposium on Advanced Network-Polymers, Kansai University (ISANKU), at Kansai University, Suita, Osaka, Japan, on December 5-6, 1995 (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 1-15 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This question was addressed using various methods to monitor the process of curing and state of the final network. Attention was particularly focused on the possible inhomogeneous network formation as a consequence of the crosslinking process. An analysis of experimental data has revealed that some cured resins can be considered as homogeneous as the corresponding uncrosslinked materials. Resins cured by simple stepwise alternating chemistries, with good compatibility of components, usually fulfill the criterion of homogeneity. A family of epoxy resins cured with polyamines belongs to this category. Nodular structures seen by electron microscopy are a result of interaction of the electron beam or etching. Such structures are also observed for uncrosslinked polymers investigated under the same conditions. Formation of inhomogeneities in a number of thermoset systems is due to (a) chainwise mechanism of network formation with fast propagation inducing cyclization and steric volume exclusion and (b) poor compatibility of components of the system made stronger by increasing molecular weights and crosslinking during curing. Networks formed by freeradical polymerization and copolymerization of polyvinyl monomers can serve as an example of crosslinking-driven formation of inhomogeneities.
    Additional Material: 7 Ill.
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    Design of network polymers by photopolymerizationLecture presented at the “International Symposium on Advanced Network Polymers, Kansai University” (ISANKU), at Kansai Univeristy, Suita, Osaka, Japan, on December 5-6, 1995. (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 83-90 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The base and transition metal catalyzed isomerization of allyl and crotyl ethers affords a facile, high yield route to the preparation of a variety of mono-, di-, and multifunctional 1-propenyl and 1-butenyl ethers. Employing this novel method, monomers containing epoxide, ester, ether carbonate and urethane groups can be prepared from their readily available allyl and crotyl precursors. In general, these monomers display very high reactivity in cationic polymerizations. In our work, we have focused on photoinduced cationic polymerizations of these monomers using diaryliodonium and triarylsulfonium salt photoinitiators. To study these very fast photopolymerizations, extensive use of real-time infrared spectroscopy was made. Employing this technique, the effects of monomer and photoinitiator structure on the rates of polymerization were studied.
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    Designing elastomer network for desired tire performance characteristics (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 137-149 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rubber elasticity is associated with changes in configurational entropy of a long chain. Because the chain cannot change its configuration instantaneously, there is a time delay in deformation to an applied force. This delayed response is the source of viscoelasticity and hysteresis energy loss of elastomer networks. Many tire performance properties are related to the viscoelasticity of tire components. Wet and dry traction of tire is related to the energy loss of the tread material at very high frequencies. On the other hand, rolling resistance of tire is characterized by the energy loss of tread material at relatively low frequencies. The dynamic viscoelastic properties of elastomer network shows characteristic zones on a frequency scale. At very high frequencies the energy loss is controlled by the segmental motions of the polymer chain. At lower frequencies the energy loss is related to the longer range motions of the chain. A series of polymers was synthesized to study the effect of micro- and macro-structure of the polymer on the viscoelastic properties of tread compounds and their tire performance properties. As expected from the theory, the wet traction of the tire was highly correlated to the segmental motions of the chains; namely, the glass transition temperature of the polymer. The energy loss of the compounds at a higher temperature, however, was related to the macrostructure of the polymer chain. Those examples illustrate that the fundamental understanding of the theory of elastomer network allows a tire engineer to obtain the best balance of tire performance characteristics.
    Additional Material: 7 Ill.
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    Molecular design of novel network polymers (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 171-180 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cationic, anionic, and radical ring-opening polymerization of spiro and bicyclic monomers, and their application to network polymers have been developed. Bicyclo orthoesters (BOEs), spiro orthoesters (SOEs), and spiro orthocarbonates (SOCs) were polymerized by cationic double ring-opening. Bicyclobis(γ-butyrolactone)s and spirobis(γ-butyrolactone)s were copolymerized with epoxides by anionic alternating ring-opening. Polymers from SOCs bearing exomethylene groups consisted of ring-opened and vinyl polymerized units. The degree of ring-opening of SOCs depended upon the number of rings and steric hindrance. The radical polymerization of vinylcyclopropanone cyclic acetals depended on the ring-size. With the monomers bearing 5- and 6-membered acetal rings, single ring-opened polymers were obtained. With the monomer bearing 7-membered acetal ring, the polymer mainly consisted of double ring-opened unit. These monomers could be crosslinked by bifunctionalization. Poly(cyclic orthoester)s linked by covalent bonds with dithiols to bifunctional SOEs were crosslinked by acid catalysts, and the reversible crosslinking-depolymerization system could be controlled by temperature.
    Additional Material: 1 Ill.
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    Characterization of polyurethane network elastomers (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 205-211 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyester urethane network elastomers with incorporated hard segment oligomers have been prepared by poly(ethylene adipate)glycol (PEA), 2,4-tolylene diisocyanate (TDI), and 1,4-butanediol (BD). These hard segment oligomers were hydroxy-terminated oligomers ([BD-TDI]n-BD; n=1,3), obtained by reacting BD with TDI. Concentrations of allophanate as a cross-linking site were determined by the amine degradation method. Hard segment moieties were obtained by a novel selective hydrolysis of soft segments in the elastomers. Molecular weight distributions of hard segment were measured by means of GPC. Mechanical and thermal properties were measured. Dependence of rubber elasticity on physical cross-linking between normal elastomers and the elastomers with incorporated hard segment oligomers were discussed.
    Additional Material: 5 Ill.
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    Network formation and swelling behavior of photosensitive poly(vinyl alcohol) gels prepared by photogenerated crosslinkingPoster presented at the “International Symposium on Advanced Network-Polymers, Kansai University” (ISANKU), at Kansai University, Suita, Osaka, Japan, on December 5-6, 1995. (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 231-239 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly (vinyl alcohol) with pendent styrylpyridinium groups (SbQ) is insolubilized by photoirradiation. An association takes place in SbQ groups. The association of polymer chains becomes marked with increasing the number of SbQ groups. Mainly intermolecular crosslinks were formed. Transparent and homogeneous macrogels consisting of several intermolecular crosslinks are obtained.The proportion of the free water to the bound water in PVA-SbQ gels was 3.3-2.9 despite of the large change in conversion of photodimerization of SbQ groups, x=0.27-0.58. The water uptake after swelling of the gels in water increased 6-27 times compared to the original weight at pH=7. The higher the degree of photocrosslinking, the lower was the degree of swelling. The water diffusion coefficients, D, were (2.2-5.8) × 10-5 cm2 S-1 for a 88% saponified PVA with 1 . 3 mol% SbQ groups. The volume of the gel increased discontinuously about 10-fold for the 99% saponified PVA with 0 . 096 mol% SbQ and 51% water (49% acetone). The acetone concentration at the transition decreased with increasing the degree of saponification of the PVA.
    Additional Material: 10 Ill.
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    Hydrogels for biomedical use based on 1-vinyl-2-pyrrolidone crosslinked with macromonomers (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 151-160 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Durch anionische Copolymerisation von Allylmethacrylat und Methylmethacrylat wurden Makromonomere unterschiedlicher Kettenlänge mit durchschnittlich drei Allyl-Doppelbindungen pro Kette hergestellt́ und mit NMR-Spektroskopie und Gelpermeationschromatographie charakterisiert. Durch Copolymerisation der Makromonomeren mit 1-Vinyl-2-pyrrolidon wurden dreidimensionale Strukturen erhalten. Die optischen und mechanischen Eigenschaften der Produkte wurden untersucht, und die Quellungseigenschaften und Vernetzungsgrade wurden bestimmt. Die Copolymereigenschaften wurden durch Makromonomere mit Kettenlängen bis 40 Einheiten nur wenig beeinflußt. Bei Kettenlängen über 50 Einheiten wurde eine leichte Abnahme der Wasseraufnahmefähigkeit und eine deutliche Erhähung des Elastizitätsmoduls beobachtet. Die Vernetzungsgrade hängen von der Makromonomer-Kettenlange ab; eine merkliche Erhöhung aufgrund der groößeren Zahl an Methyl-Methyl-Wechselwirkungen wurde bei Kettenlangen über 50 Einheiten festgestellt. Die Copolymeren zeigen günstige Festigkeits-Dehnungs-Eigenschaften und einen geringen Gehalt an wasserlöslichen Extrakten, in denen durch IR-Spektroskopie 1-Vinyl-2-pyrrolidon-Homopolymere identifiziert wurden. Obwohl mit allen untersuchten Makromonomeren gute Resultate erzielt wurden, scheint für die Copolymerisation mit 1-Vinyl-2-pyrrolidon das Makromonomere mit 50 Einheiten am besten geeignet.
    Notes: Macromonomers of various chain lengths with an average of three allyl double bonds per chain were prepared by anionic copolymerization of allyl methacrylate with methyl methacrylate. The macromonomers were characterized by gel permeation chromatography and nuclear magnetic resonance. The macromonomers were then copolymerized with 1-vinyl-2-pyrrolidone to form three-dimensional structures. Their optical, swelling and mechanical properties were studied and the crosslinking efficiency was determined. The copolymer properties are not greatly affected by macromonomer chain lengths up to 40-mers; above 50-mers there is a slight decrease in the equilibrium water content and a significant increase in the modulus of elasticity. The crosslinking efficiency depends on the macromonomer chain length; a marked increase was observed for the 50-mer because of a greater number of methyl-methyl interactions. Copolymers have favourable strength-strain properties and a low content of water-soluble extracts, in which the IR analysis demonstrated the presence of 1-vinyl-2-pyrrolidone homopolymers. In spite of the good results obtained for all the macromonomers described in this work, the 50-mer seems to be optimal for copolymerization with 1-vinyl-2-pyrrolidone.
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    Zur härtung von diandiglycidylether mit anhydridmodifizierten phenolischen härtern und zu vergleichbaren in situ-reaktionen (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 201-213 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The curing of diglycidyl ether of bisphenol A (DGEBA) with 2,6-dimethylol-p-cresol modified by hexahydrophthalic acid anhydride was investigated and compared with the analogous in situ curing of DGEBA, hexahydrophthalic acid anhydride and 2,6-dimethylol-p-cresol. The chemical reactions were investigated by means of titration and different spectroscopic and chromatographic methods. It was examined whether the less complicated and therefore cheaper in situ reaction delivers postcured products with equal or better properties. Furthermore, it was investigated whether the results are similar using technical phenolic hardeners.
    Notes: Die Härtung von Diandiglycidylether (DDGE) mit hexahydrophthalsäureanhydridmodifiziertem 2,6-Dimethylol-p-kresol (HHPSA-DMPK) wurde untersucht und mit der in situ durchgeführten Vernetzung von DDGE mit Hexahydrophthalsäureanhydrid (HHPSA) und 2,6-Dimethylol-p-kresol (DMPK) verglichen. Die chemischen Reaktionen wurden durch Titration der Epoxidgruppen und mit verschiedenen spektroskopischen und chromatographischen Methoden untersucht. Es wurde geprüft, ob die weniger aufwendige und daher preiswertere in situ-Härtung zu Produkten mit gleichen oder besseren Endeigenschaften führt. Weiterhin wurde die Übertragbarkeit der Ergebnisse auf den Einsatz technischer Phenolharzhärter getestet.
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    Characterization and application of poly(vinyl alcohol)/starch composite as a sizing agentResults published in this paper were extracted from the Ph. D. Thesis to be submitted by M. M. Hashem to Cairo University, Egypt. (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 241 (1996), S. 149-163 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zur Entwicklung neuartiger ökologisch verträglicher makromolekularer Schlichtemittel wurden in früheren Arbeiten Copolymerisationsreaktionen zwischen Polyvinylalkohol (PVA) und Stärke unter Verwendung von chemisch reaktiven bifunktionellen Verbindungen wie N-Methylolacrylamid beschrieben. Im Rahmen dieser Arbeit werden die physikochemischen Eigenschaften des resultierenden Copolymeren untersucht. Von Bedeutung sind hierbei insbesondere Merkmale wie Molekulargewichtsverteilung, Klebekraft, Stabilität, Löslichkeit sowie rheologische Eigenschaften. Derartige Kenntnisse über die physikochemische Beschaffenheit der PVA-Ausgangsverbindung sowie des makromolekularen Endproduktes sind eine wesentliche Voraussetzung für die Entwicklung von neuen Produkten, die als wasserlösliche, recycelbare Schlichtemittel zur Anwendung in der Textilindustrie kommen können.
    Notes: A macromolecular sizing agent based on the copolymerization of poly(vinyl alcohol) (PVA) with hydrolysed starch was prepared using the chemically reactive bifunctional compound N-methylolacrylamide. Detailed characteristics of the resultant PVA/N-methylolcarbamoylethylated starch copolymer were studied where emphasis has been placed on solubility, rheological properties, molecular weight distribution, adhesive power and stability. Elucidation of the nature of the macromolecular segments of both N-methylolcarbamoylethylated PVA as well as PVA/N-methylolcarbamoylethylated starch copolymer fulfilled the prerequisite to tailor PVA/starch copolymer which is appropriate for application as a water-soluble recyclable sizing agent by ultrafiltration.
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    Peripherally restraining type rubber bearingLecture presented at the “International Symposium on Advanced Network-Polymers, Kansai University” (ISANKU), at Kansai University, Suita, Osaka, Japan, on December 5-6, 1995. (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 151-162 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Seismic isolation was reconfirmed to be extremely efficient for the protection of buildings, and hence human life, on the occasion of the Great Hanshin Earthquake. Rubber bearings are placed under the buildings for isolation, and thus the type of rubber bearings is a dominant factor for efficient isolation. In this report, the performance of peripherally restraining type rubber bearing (PRB) was examined where its contracted model was found to simulate the performance of full scale PRB precisely. Damping ratio and vertical spring constant of PRB are as good as the existing ones. PRB showed lower critical shear strain, but it was concluded that no problems were found for the actual use of PRB.
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    Computational study of network formation of phenolic resinsPoster presented at the “International Symposium on Advanced Network-Polymers, Kansai University” (ISANKU), at Kansai University, Suita, Osaka, Japan, on December 5-6, 1995. (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 181-186 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The network formation of phenol-formaldehyde resin was investigated by the Monte Carlo (MC) simulation technique. The observed value of the gel point, pc, was exactly determined as a critical extent of reaction, where the Mw/Mn in soluble parts is maximum. The MC simulation with the cubic percolation theory was applied to the gelation of phenolic resins and gave an exact gel point, which was in excellent agreement with the observed value of pc. The simulation showed that the intramolecular reaction occurred frequently with increasing the gel fraction beyond the gel point. The structural analysis of the maximum cluster with the computer strongly supported the contribution of the intramolecular reaction to the network formation of the gel.
    Additional Material: 5 Ill.
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    PH-induced structure change of poly(vinyl alcohol) hydrogel crosslinked with poly(acrylic acid)Poster presented at the “International Symposium on Advaned Network-Polymers, Kansai University”(ISANKU), at Kansai University, Suita, Osaka, Japan, on December 5-6, 1955. (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 213-219 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The structure of the hydrogel of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) was investigated by small angle X-ray scattering (SAXS) of synchrotron radiation. A physically crosslinked blend gel, which was prepared by repetitive freezing and thawing of an aqueous solution of PVA and PAA, could be chemically crosslinked by esterfication of PVA with PAA even in the hydrogel state. The chemical crosslinking induced the destruction of physical crosslinks into a folded structure, indicating that the chemical crosslinking proceeds at the sites around the physical crosslinks that contain PVA and PAA in much higher concentration than other portion of the gel. The pH-induced structure changes of the PVA hydrogels, chemically crosslinked with poly(acrylic acid) (PAA) were investigated by SAXS on the samples of various chemical crosslinking time. The gels were shrunk at pH4, and swollen at pH8. The results of SAXS showed, that the Porod slope changed with chemical crosslinking time from -3.5 to -2.9 at pH4, and from -2.9 to -2.4 at pH8. The results suggest that a folded structure as a structural domain, which is characterized by fractally rough interface, tends to change into the structure that corresponds to percolation cluster, particularly at pH8. The gels immersed in pH8 showed a remarkable structure change accompanying swelling. The results revealed that a conformational change of PAA chains, induced by the pH change, can be explained by the presence of a structural domain in the gel network, where both PVA chains and PAA chains get entangled and partially form a interpenetrating polymer network(IPN).
    Additional Material: 4 Ill.
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    Polyurethane-elastomer-actuatorPoster presented at the “International Symposium on Advanced Network-Polymers, Kansai University” (ISANKU), at Kansai University, Suita, Osaka, Japan, on December 5-6, 1995. (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 221-229 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyurethane elastomers were investigated as electrically active materials for actuators. Components in hard segment and soft segment in the elastomers were varied. The elastomers with excellent electrostrictive properties were limited to those which had soft segments of polyesters and polylactones. It turned out, that the elastomers, whose soft segments are polyethers are electrically inert under the experimental conditions. The chemical structure of the hard segment seems not to influence to the electrostrictive property. The charging and discharging process was investigated. The charging process was found to proceed simultaneously with the contracting process caused by the electric field, suggesting that the orientation of the soft segment in the elastomer plays critical rolls in the electrostrictive action. In the elastomer, which has a soft polyether segment and was inactive to the electric field, could be actuated very efficiently when the elastomer was swollen with dimethyl sulfoxide. We conclude that the polyurethane elastomer, whose soft segment has chemical bonds with a relatively large dipole moment, can be actuated by the electric field application, and that even the elastomer, whose soft segment is inactive, could be actuated in the presence of a solvent with a large dipole moment. Thus, the concept found with the gel, could be applied to an elastomer, the soft segment of which plays partly the roll of the solvent in the gel.
    Additional Material: 5 Ill.
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    Preparation of oxidized 6-O-glycolchitosan, pH sensitivity of its aqueous solution and of its cross-linked hydrogel (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 263-273 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Chitosan and 6-O-glycolchitosan, a water-soluble chitosan derivative, were oxidized by periodate. In the case of chitosan, only degradation products were obtained. With 6-O-glycolchitosan, however, water-soluble amphoteric polyelectrolyte derivatives of chitosan having higher molecular weight were obtained. The oxidized 6-O-glycolchitosan (OX-GC) showed a pH sensitive change of viscosity in aqueous solution. Moreover, the OX-GC hydrogel, cross-linked with glutaraldehyde, showed a pH sensitive swelling behavior. The OX-GC showed biodegradation behavior by lysozyme after acetylation.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1996.052400125
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    A polymer network of unsaturated polyester and bismaleimide resins: Yielding and fracture behaviour (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 241 (1996), S. 11-29 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das Fließ- und Bruchverhalten eines durch das gleichzeitige Härten eines ungesättigten Polyesters (UP) und eines wärmehärtbaren Bismaleimidharzes (BMI) erhaltenen quervernetzten Polymernetzwerkes wurde über einen weiten Temperatur- und Beanspruchungsbereich untersucht. Die Fließspannung σy und der Youngsche Elastizitätsmodul E steigen bei Zunahme der Spannungsbeanspruchung bzw. bei Absinken der Temperatur. Zudem steigen bei ansonsten gleichen Testbedingungen σy und E mit zunehmendem BMI-Gehalt im Blend. Andererseits wurde eine Beeinflussung des Bruch-Parameters Kc durch die Gegenwart des BMI nicht beobachtet. Der Fließprozess wurde sowohl mit Hilfe der Theorie von Argon als auch mit der von Bowden untersucht; die daraus abgeleiteten Molekül-Parameter wurden mit der bei der Härtung gebildeten Molekularstruktur in Beziehung gesetzt.
    Notes: The yielding and the fracture behaviour of an intercrosslinked polymer network obtained by the simultaneous curing of an unsaturated polyester (UP) and a thermosetting bismaleimide resin (BMI) was investigated in a wide range of temperatures and testing rates. The yield stress σy and the Young's modulus E increase by increasing the testing rate and decreasing temperature. Moreover, under the same testing conditions, σy and E increased as the BMI content in the blend was enhanced. On the other hand, it was found that the fracture parameter Kc was not affected by the presence of BMI. The yielding process was analyzed using the theories both of Argon and Bowden and the molecular parameters derived there were related to the molecular structure of the network developed upon curing.
    Additional Material: 13 Ill.
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    Fluorinated poly(1,3,4-oxadiazole-imide-amide)s (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 242 (1996), S. 159-169 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Dicarbonsäuredichloride mit sowohl Hexafluorisopropyliden-Brücken und Imidringen im Molekül wurden mit p-Aminobenzhydrazid oder Mischungen aus aromatischen Diaminen und p-Aminobenzhydrazid oder Terephthaldihydrazid zu Poly(hydrazidimid-amid)en umgesetzt, die anschließend zu neuen fluorhaltigen Poly(1,3,4-oxadiazol-imid-amid)en mit verschiedenem Amid/Oxadiazol-Verhältnis cyclodehydriert wurden. Diese sind in polaren amidischen Lösungsmitteln löslich; aus solchen Lösungen lassen sich flexible Filme herstellen. Die Glasübergangstemperaturen liegen zwischen 254°C und 325°C. Sie sind bis zu 415-450°C thermisch stabil.
    Notes: A series of new fluorinated poly(1,3,4-oxadiazole-imide-amide)s containing various ratios of amide/oxadiazole groups in the repeating unit have been prepared by cyclodehydration of the corresponding poly(hydrazide-imide-amide)s resulting from the reaction of diacid dichlorides incorporating both hexafluoroisopropylidene bridges and imide rings with p-aminobenzhydrazide or with mixtures of certain aromatic diamines and p-aminobenzhydrazide or terephthalic dihydrazide. The new polymers are soluble in polar amidic solvents and can be processed into flexible films by casting from solution. Their glass transition temperatures are in the range 254-325°C and they are thermally stable up to 415-450°C.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1996.052420111
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    Electric resistivity of hydroscopic copoly(ester-ether)s containing zwitterionic units and their utilization for antistatic modification of polyester fiber (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 242 (1996), S. 171-181 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Blockcopoly(ester-ether) mit verschiedenen ionischen Einheiten wie Sulfobetain (S-Betain), Carbobetain (C-Betain) und Ammoniumtosylat wurden hergestellt und hinsichtlich ihrer Eignung als antistatische Modifikatoren für Polyethylenterephthalat (PET)-Fasern untersucht. Die ionischen Segmente wurden aus N,N-Bis(2-hydroxyethyl)methylamin generiert und statistisch mit den Polyester- und Polyoxyethylen(PEO)-Einheiten cokondensiert. Aus den Copolymeren mit S-Betain-Einheiten wurden im Schmelzspinnverfahren dicke Filamente hergestellt und deren elektrischer Widerstand bestimmt. Abhängig von der Zusammensetzung (25-75 Gew.-% PEO, 1-2 mol-% S-Betain) wurden Widerstände zwischen 108 und 1010 Ω cm-1 gemessen. Die drei copolymerartigen Modifikatoren wurden mit PET durch Blendspinnen gemischt. Die so erhaltenen PET-Fasem zeigen nicht nur gute mechanische sondern auch verbesserte antistatische Eigenschaften. Die Fasern aus dem S-Betain enthaltenden Copolymeren weisen dabei die kürzeste Halbwertszeit des Abbaus der elektrostatischen Ladung auf, obwohl der Oberflächenwiderstand dieses Materials in der Größenordnung 1013 Ω cm-2 dem Wert der mit C-Betain und Ammoniumtosylat hergestellten Fasem ähnlich ist. Die PET-Fasern bewahren ihre guten antistatischen Eigenschften auch nach dem Fäben und wiederholtem Waschen, da sowohl die hydrophilen als auch die ionischen Gruppen an den Polyesterketten fixiert sind.
    Notes: Block copoly(ester-ether)s containing different ionic units, i.e., sulfobetaine (S-betaine), carbobetaine (C-betaine), and ammonium tosylate, were prepared and evaluated as antistatic modifiers of PET fiber. The ionic units were readily derived from N,N-bis(2-hydroxyethyl)methylamine and co-condensed randomly with the polyester and poly(oxyethylene) (PEO) units. For the copolymers containing S-betaine units, a thick filament was melt-spun to evaluate their apparent electric resistivity. Depending on the unit compositions (25-75 wt.-% of PEO and 1-2 mol-% of S-betaine), resistivities ranging from 108 to 1010 Ω cm-1 were obtained. Then, the three copolymer-type modifiers were blended with poly(ethylene terephthalate) (PET) by the ordinary blend-spinning technique. The blend PET fibers obtained showed not only good mechanical properties, but also improved antistatic properties. Particularly, the fiber blended with the copolymer containing S-betaine units had the shortest half-life time of leakage of static charge, although the surface area resistivity, being in the order of 1013 Ω cm-2, was similar to that of the fibers blended with the copolymers containing C-betaine and ammonium tosylate units. These blend PET fibers were found to retain good antistatic properties even after dyeing and repeated washings, because both the hydrophilic and ionic groups are immobilized with the polyester chains.
    Additional Material: 3 Tab.
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    Untersuchungen zum reaktionsverhalten beim vorliegen von depolymerisationsreaktionen. Untersuchung von copolymerisationen des α-methylstyrols (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 243 (1996), S. 11-37 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: For radical copolymerizations of α-methylstyrene (MS) with methacrylonitrile (MAN) and of MS with acrylonitrile (AN) studies were carried out to examine postulations of kinetic models known from literature, in particular the terminal model with chain-length-independent and chain-length-dependent depolymerization steps. The results of investigations were based on measurements of the sequence length distributions from 13C-NMR spectra. Analyses of MS/MAN copolymers with various compositions were carried out. Reaction parameters and depolymerization constants depending on temperature were calculated. The values of enthalpy and entropy of polymerization and the ceiling temperature were computed for MS to ΔH = 26,5 ± 0,5 kJ mol-1, ΔS = 95 ± 5 J mol-1 K-1, Tceiling = 65 ± 1°C. The terminal model with depolymerization steps turned out to be wrong for the accurate description of the polymerization behaviour in case of the tested systems. Results clearly show important penultimate effects. At the point of knowledge, the description of the polymerization behaviour in terms of a penultimate model with depolymerization steps are suggested.
    Notes: Für die radikalischen Copolymerisationen von α-Methylstyrol (MS) mit Methacrylnitril (MAN) sowie MS mit Acrylnitril (AN) wurden Untersuchungen zur Prüfung der in der Literatur postulierten kinetischen Modelle des „sequenzlängenunabhängigen“ bzw. „sequenzlängenabhängigen“ Terminalmodells mit Depolymerisationsschritten durchgeführt. Sie basieren auf Analysen der Sequenzverteilungen aus 13C-NMR-Spektren. Resultate von 13C-NMR-Untersuchungen an MS/MAN-Polymeren variabler Zusammensetzung werden vorgestellt. Reaktionsparameter und Gleichgewichtskonstanten wurden direkt aus den Informationen der 13C-NMR-Spektren für das Terminalmodell mit Depolymerisationsschritten in Abhängigkeit von der Reaktionstemperatur der Polymeren bestimmt. Hieraus konnten die Polymerisationsenthalpie ΔH = 26,5 ± 0,5 kJ mol-1, die Polymerisationsentropie ΔS = 95 ± 5 J mol-1 K-1 sowie die Ceilingtemperatur Tceiling = 65 ± 1°C für MS bestimmt werden. Es wurde nachgewiesen, daß im Rahmen der Terminalnäherung auch mit Berücksichtigung von Depolymerisationseinflüssen keine adäquate Beschreibung des Copolymerisationsverhaltens im Falle der untersuchten Systeme möglich ist. Vielmehr konnten als Ergebnis der Untersuchungen sowohl in Copolymeren von MS mit AN als auch mit MAN signifikante Penultimate-Effekte nachgewiesen werden. Aufbauend auf diesen Ergebnissen wird die Anwendung eines auf einer Penultimate-Näherung basierenden Modells, welches auch das Gleichgewicht in den Wachstumsreaktionen von MS berücksichtigt, zur theoretischen Vorhersage des Copolymerisationsverhaltens vorgeschlagen.
    Additional Material: 14 Ill.
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    Epoxidation of cis-cyclooctene with molecular oxygen catalyzed by magnesium oxide supported polytitazane cobalt (III) complexes (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 243 (1996), S. 69-75 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein auf Magnesiumoxid aufgebrachter Polytitazan-Cobalt (III)-Komplex diente als effektiver Katalysator für die Epoxidierung von cis-Cycloocten mit molekularem Sauerstoff bei Normaldruck in Gegenwart von Isobutyraldehyd als Reduktionsmittel. Nach XPS-Untersuchungen wird Cobalt (III) durch den mehrzähnigen Stickstoffliganden des Polytitazans stabilisiert. Bei 25°C beträgt der cis-Cycloocten-Umsatz nach fünf Stunden 95,2%, mit einer Selektivität von 100% für das cis-Cyclohexylenoxid. Der Katalysator Kann mindestens neun Mal ohne Aktivitätsverlust verwendet werden.
    Notes: Magnesium oxide supported polytitazane cobalt (III) complex is demonstrated as an effective catalyst for the epoxidation of cis-cyclooctene with molecular oxygen at atmospheric pressure in the presence of isobutyraldehyde as the sacrificial reductant. XPS data show that the high-valent cobalt (III) is stabilized by the multidentate nitrogen ligand of polytitazane. The conversion of cis-cyclooctene is as high as 95.2% with 100% selectivity to the cis-cyclooctene oxide at 25°C within 5 h. The catalyst can be used at least nine times without loss of its activity.
    Additional Material: 2 Ill.
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    Phase diagram and crystallization of polycarbonate/poly-∊-caprolactone blends (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 243 (1996), S. 177-187 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wird über die Gleichgewichts-Schmelzpunktsdepression von Polycarbonat aus Bisphenol A (PC) in Mischungen mit Poly-∊-caprolacton (PCL) berichtet. Hierzu wird ein Modell entwickelt, das den gekrümmten Verlauf der gemessenen Hoffman-Weeks-Plots zu erklären vermag. Es berücksichtigt die Konzentrationsinhomogenitäten, die mit fortschreitender Kristallisation an der Kristallwachstumsfront entstehen. Die gelegentlich beobachtete Schmelzpunktsdepression der PCL-Komponente wird diskutiert. Der Flory-Hugginssche Wechselwirkungsparameter wird zu -0,09 berechnet; aus diesem kleinen Wert muß geschlossen werden, daß die Mischungspartner enthalpisch nur schwach wechselwirken. Der merkliche Abfall der Glastemperatur des PC nach Einmischen von PCL bewirkt eine beträchtliche Kristallisation aus der Schmelze; es können PC-Kristallinitätsgrade bis zu 25% erreicht werden.
    Notes: It is reported on the equilibrium melting point depression of polycarbonate from bisphenol A (PC) in its blend with poly-∊-caprolactone (PCL). To this end, a model which explains the bended course of the measured Hoffman-Weeks plots is developed which takes into account the composition changes at the crystal growth front upon progressive crystallization. The occasional melting point depression of the PCL component is discussed. The calculated Flory-Huggins parameter of χ12 ≍ -0.09 indicates only weak enthalpic interactions. The remarkable drop in the glass transition temperature of PC with blending allows PC degrees of crystallinity up to 25% upon crystallization from the melt.
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    Synthesis and properties of powdery hydrogels based on acrylamide, methacrylamide, and their N-substituted derivatives (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 243 (1996), S. 151-159 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Leicht vernetzte Hydrogele auf der Basis von Acrylamid, N-(1,1-Dimethyl-3-oxobutyl)acrylamid, N,N-Dimethylacrylamid, Methacrylamid, N-(2-Hydroxypropyl)-methacrylamid und N-[Tris(hydroxymethyl)methyl]methacrylamid wurden in Form von pulverigen Substanzen synthetisiert, die aus Aggregaten sehr kleiner Partikel (∼10-1 μm) bestehen. Die pulverartigen Hydrogele wurden durch Fällungspolymerisation in Aceton und Diethylether unter Verwendung von N,N′-Methylenbisacrylamid und Ethylendimethacrylat als Vernetzungsmittel synthetisiert. Es wurden die Abhängigkeiten des Quellungsgrades in Wasser, der Größe, des Aggregationsgrades und der spezifischen Oberfläche von Partikeln, und des Inhalts von wasserlöslichen Substanzen in den Hydrogelen von den Bedingungen ihrer Synthese verfolgt. Die Eignung einzelner der synthetisierten Hydrogele für die Herstellung von Silikon-kautschuk-Hydrogel-Kompositen wird diskutiert.
    Notes: Lightly crosslinked hydrogels based on acrylamide, N-(1,1-dimethyl-3-oxobutyl)-acrylamide, N,N-dimethylacrylamide, methacrylamide, N-(2-hydroxypropyl)methacrylamide and N-[tris(hydroxymethyl)methyl]methacrylamide were synthesized in form of fine powders, consisting of aggregates of very small (∼10-1 μm) particles. The powdery hydrogels were obtained by precipitation polymerization in acetone and diethyl ether, using N,N′-methylenebisacrylamide and ethylene dimethacrylate as crosslinking agents. Dependences of water-swellability, particle size, aggregation, specific surface and content of the uncrosslinked water-soluble polymers and low-molecular-weight substances in the hydrogels on the conditions of their synthesis were studied. Suitability of particular powdery hydrogels synthesized for the preparation of silicone rubber-hydrogel composites is discussed.
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    Polymerization of lactams, 87Part 86 cf.21.. Block copolymers of poly(∊-caprolactam) and polybutadiene prepared by anionic polymerization. Part I: Preparation and properties (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 237 (1996), S. 123-141 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde der Einfluß der Polymerisationsbedingungen auf die Eigenschaften von Poly(∊-Caprolactam)-Polybutadien-Blockcopolymeren untersucht, die durch Reaktionsformgießen bei der anionischen ∊-Caprolactam-Polymerisation, initiiert durch das ∊-Caprolactam-Kaliumsalz, in Anwesenheit von α,ω-Dihydroxypolybutadien und Isocyanaten oder deren blockierter Derivate als Funktionalisierungsmittel hergestellt wurden.Es wurde der Einfluß des Polybutadiengehalts, dessen Molekulargewichts, des Isocyanat-Typs und der Polymerisationstemperatur auf die mechanischen Grundeigenschaften und auf die Polymerisationsgeschwindigkeit bestimmt.
    Notes: The effect of the polymerization conditions on the properties of poly(∊-caprolactam)-polybutadiene block copolymers prepared by polymerization casting through anionic polymerization of ∊-caprolactam initiated with potassium salt of ∊-caprolactam in the presence of α,ω-dihydroxy-polybutadiene and isocyanates or their blocked derivatives as functionalizing agents was investigated.The influence of the content of telechelic polybutadiene, its molecular weight, type of diisocyanate, and polymerization temperature on the fundamental mechanical properties of the prepared materials and on the polymerization rate was evaluated.
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    Synthesis of tetrahydrofuran-styrene and tetrahydrofuran-methyl methacrylate block copolymers via poly(tetrahydrofuran) with azo groups (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 238 (1996), S. 55-62 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Tetrahydrofuran (THF) wurde mit dem Initiatorsystem 4,4′-Azobis(4-cyanopentanoylchlorid)/SnCI4 kationisch polymerisiert. Das gebildete Poly(THF) mit je einer Azogruppe in der Hauptkette wurde als Initiator für die Polymerisation von Styrol (S) und Methylmethacrylat (MMA) bei 70°C eingesetzt. Die dabei entstandenen PTHF-PS-PTHF- bzw. PTHF-PMMA-Blockcopolymeren wurden mittels Fällungsfraktionierung, spektroskopischen Methoden und Viskositätsmessungen charakterisiert.
    Notes: The cationic polymerization of tetrahydrofuran (THF) initiated by 4,4′-azobis(4-cyanopentanoyl chloride) (ACPC) and SnCI4 is described. Poly(THF) samples possessing azo gorups in the main chain thus obtained were used as initiator in the polymerization of styrene (S) and methyl methacrylate (MMA) at 70°C to yield PTHF-PS-PTHF and PTHF-PMMA block copolymers. Characterization of the block copolymers was carried out by fractional precipitation, spectroscopic methods and viscosity measurements.
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    The effects of a slushing oil on the curing and degradation behavior of an oil-accommodating epoxy adhesive (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 238 (1996), S. 129-141 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Wirkung von aliphatischem Korrosionsschutzöl auf das Aushärte- und Abbauverhalten eines ölkompatiblen Epoxidharzklebers wurde mittels Differentialkalorimetrie (DSC), Fourier-Transformations-Infrarot-Spektroskopie (FTIR) und Thermogravimetrie (TGA) untersucht. Die Ergebnisse der DSC- und FTIR-Messungen deuten darauf hin, daß die Härtungsgeschwindigkeit des untersuchten Epoxid-Systems durch das Vorhandensein des Öls nur wenig beeinflußt wird. Dennoch bestätigt das Absinken der exothermen Härtungskurve, begleitet von einer Verbreiterung des Glasübergangstemperaturbereichs, daß das Öl den Aushärtemechanismus beeinflussen kann und in der Lage ist, die Struktur des gehärteten Harzes zu verändern. Außerdem geht aus den TGA-Messungen hervor, daß die Temperaturbeständigkeit des Harzes sich in Gegenwart des Öls verschlechtert; dies wird auf Veränderungen in der Struktur und im Abbaumechanismus des Epoxid-Systems zurückgeführt.
    Notes: The effect of aliphatic slushing oil on the curing and degradation behavior of an oil-accommodating epoxy adhesive is studied by using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The results of FTIR and DSC indicate that the curing rate of the tested epoxy system is little affected in the presence of the oil. However, the decrease of the curing exotherm accompanied with a broadening of the glass transition confirms that the oil can affect the curing mechanisms and may change the structure of the cured resin. Additionally, it is evident from the TGA results that the thermal resistance of the resin deteriorates in the presence of the oil, which is attributed to the changes in the structure and the degradation mechanism of the epoxy system.
    Additional Material: 6 Ill.
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    Electrochemical polymerization of some monomers with schiff's base structure. A voltammetric study (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 1-12 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die elektrochemische Polymerisation von Pyrrol-2-aldehyd-azin, 2,2′-[1,4-Phenylenbis(nitrilomethylidyn)]dipyrrol und 2,2′-[1,4-Biphenylylenbis(nitrilomethylidyn)]dipyrrol läuft als anodische Fällungspolymerisation ab. Monomere und Polymere wurden voltammetrisch unter Verwendung von Platin- und “Paste-carbon”-Elektroden untersucht. Die Ergebnisse stimmen mit MO-Berechnungen überein, wobei die Reaktivität der Monomeren nach Hückel abgeschätzt wurde.
    Notes: The electrochemical polymerization of some Schiff's base-type monomers like pyrrole-2-aldehyde azine, N,N′-di(2-pyrrolylmethylene)-1,4-diaminobenzeneSystematic name: 2,2′-[1,4-phenylenebis(nitrilomethylidyne)]dipyrrole., and N,N′-di(2-pyrrolylmethylene)-4,4′-diaminobiphenylSystematic name: 2,2′-[4,4′-biphenylylenebis(nitrilomethylidyne)]dipyrrole. proceeds as a precipitating polymerization to the anodic compartment. The voltammetric study of monomers and polymers using Pt electrodes and paste-carbon electrodes were carried out. The results are in agreement with the MO calculations using the Hückel approximation for evaluating of the reactivity of the monomers.
    Additional Material: 7 Ill.
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    Stereoselective polymerization of butadiene by a new dicationic nickel complex (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 33-41 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der neuartige dikationische Komplex [dppfNi(MeCN)4][BF4]2 (dppf = 1,1′-Bis(diphenylphosphin)ferrocen) zeigte in Anwesenheit von Diethylaluminiumchlorid (AIEt2CI) hohe Aktivität für die Polymerisation von 1,3-Butadien. Reaktionsdauer, Temperatur und das Aluminium/Nickel-Verhältnis wurden auf maximale Aktivität und Selektivität optimiert. Umsätze über 90% konnten erreicht werden. Im Vergleich zu Polybutadienen, die mit anderen Nickel-Phosphin-Systemen hergestellt wurden, zeigten die synthetisierten Polybutadiene höhere cis-1,4-Anteile (〈80%) und eine geringe Bildung von 1,2-Einheiten (2%). Alle Polymeren hatten niedrige mittlere Molekulargewichte (Mw 〉 11 800).
    Notes: The new dicationic nickel complex [dppfNi(MeCN)4][BF4]2 (dppf = 1,1′-bis(diphenylphosphino)ferrocene) in the presence of diethylaluminium chloride (AIEt2CI) exhibited high activity on the 1,3-butadiene polymerization. Reaction time, temperature and aluminium/nickel molar ratio were optimized in order to achieve maximum activity and selectivity. Conversions higher than 90% were obtained in contrast to other nickel-based systems using phosphine ligands, the resulting polybutadiene showed high cis-1,4 (〈80%) content and only small amount of 1,2-units (2%). All polymers presented low molecular weights (Mw 〉 11 800).
    Additional Material: 2 Ill.
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    Structural changes in poly(methyl methacrylate) during deep-etch X-ray synchrotron radiation lithography. Part II: Radiation effects on PMMAPart I cf.1. Dedicated to Prof. Dr. Werner Borchard on the occasion of his 60th birthday (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 79-91 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Bei der Bestrahlung von Polymethylmethacrylat (PMMA) mit Röntgensynchrotronstrahlung ändert sich die chemische Struktur des Polymeren. Die Ergebnisse der analytischen Untersuchungen dieser Arbeit weisen darauf hin, daß neben einem Abbau der Polymerketten auch einzelne Esterseitengruppen abgespalten werden. Durch die Bestrahlung entstehende Langkettenverzweigungen wurden bei PMMA nicht gefunden. Dadurch unterscheiden sich die physikalischen und chemischen Eigenschaften des bestrahlten Polymeren von denen des unbestrahlten.
    Notes: The irradiation of poly(methyl methacrylate) changes the chemical constitution of the polymer. In addition to a decrease in molar mass further radiation-induced radical reactions cause changes in the chemical constitution of the polymer. Analysis of the reaction products shows that formation of long-chain branching can be excluded. Along with degradation of the chain lengths, ester groups in the side chains are attacked. The result is a modified polymer with a physical and chemical behaviour different from that of the starting polymer.
    Additional Material: 6 Ill.
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    Synthesis of flexible polyarylates by interfacial polycondensation. Part II: Incorporation of 4,4′-thiodiphenol (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 133-149 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Zähigkeit von Polyarylaten wurde durch den Einbau von 4,4′-Thiodiphenol und Bisphenol A, die in der wäßrigen Phase einer Grenzflächenpolykondensation vorgelegt wurden, erhöht. Die modifizierten Polyarylate besitzen leicht erniedrigte Zugfestigkeiten und Zugmoduli, aber aufgrund der Flexibilität der eingebauten Segmente stark erhöhte Izod-Schlagzähigkeiten. Darüber hinaus bleiben die guten thermischen Eigenschaften der Polyarylate nach der Modifizierung erhalten, so daß die hergestellten Materialien auch für Anwendungen mit sehr hohen Anforderungen an die thermische Belastbarkeit geeignet sind.
    Notes: The toughness of polyarylates was improved by incorporation of 4,4′-thiodiphenol and bisphenol A, being introduced in the aqueous phase of an interfacial polycondensation reaction. The modified polyarylates possessed slightly lower tensile strength and modulus but much higher Izod impact strength due to the flexibility of the incorporated segments. In addition, the superb thermal properties typical for polyarylates were reserved in the modified polyarylate, thus assuring its broad applicability for those applications where extremely stringent criteria of thermal characteristics are required.
    Additional Material: 16 Ill.
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    Le rôle des systèmes photoamorceurs dans l'efficacité de photoréticulation de l'homopolymère dicyclopentadiène acrylateNom systématique: Tricyclo[5.2.1.02.6]déc-4-en-8-yl acrylate. (DCPA) et acrylate d'éthyle (AE) et des dérivés copolymères DCPA/AE (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 169-190 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The photocrosslinking efficiency of a series of commercial photoinitiators and multicomponent photosensitive systems on uncrosslinked acrylic matrices has been estimated. Copolymers used for this study are tricyclo[5.2.1.02,6]dec-4-en-8-yl acrylate/ethyl acrylate copolymers of variable composition (100/0, 40/60, 20/80, 0/100) synthesized in solution by a free-radical process. The irradiations were carried out at large wavelengths (λ ≥ 310 nm). Systems of benzophenone/benzoyl peroxide led to really fast crosslinking kinetics for 10 min of irradiation.
    Notes: L'efficacité de photoréticulation de toute une série de photoamorceurs commerciaux et de systèmes photosensibles multicomposants a été évaluée sur des matrices acryliques non réticulées. Les polymères utilisés pour cette étude sont des homopolymères et des copolymères d'acrylate de dicyclopentadiène/acrylate d'éthyle de composition variable (100/0, 40/60, 20/80, 0/100) synthétisés en solution par voie radicalaire. Les irradiations ont été effectuées à des grandes longueurs d'ondes (λ ≥ 310 nm). Les systèmes benzophénone/peroxyde de benzoyle ont permis d'obtenir des cinétiques de réticulation très rapides pour des temps d'irradation de 10 min.
    Additional Material: 12 Tab.
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    Ideal crosslinked-polymers and their characterization in free-radical monovinyl-divinyl copolymerizationsPoster presented at the “International Symposium on Advanced Network-Polymers, Kansai University” (ISANKU), at Kansai University, Suita, Osaka, Japan, on December 5-6, 1995. (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 275-284 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The critical conditions in which the classical Flory-Stockmayer gelation theory (F-S theory) is applicable to monovinyl-divinyl copolymerizations were pursued in detail. The resulting prepolymers or precursors of ideal crosslinked-polymers were characterized as standard polymers for the discussion of network formation in free-radical monovinyl-divinyl copolymerizations. Methyl methacrylate was copolymerized with a small amount of ethylene dimethacrylate, butylene dimethacrylate or nonapropyleneglycol dimethacrylate in the presence of lauryl mercaptan, a chain transfer agent to reduce the occurrence of a thermodynamic excluded volume effect and intramolecular crosslinking as the primary and secondary factors, respectively, for the greatly delayed gelation in the free-radical monovinyl-divinyl copolymerizations and, moreover, to keep the primary chain length constant by inhibiting a gel effect. The ratio of the actual gel point to the theoretical one reached 1.1, supporting the validity of F-S theory. The resulting prepolymers were subjected to SEC-MALLS analysis to determine the molecular weights, the molecular-weight distributions and the radii of gyration; the correlations of molecular weight vs. elution volume and radius of gyration vs. molecular weight were useful for the characterization of the precursors of ideal network-polymers.
    Additional Material: 8 Ill.
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    Chemical reactions on polysaccharides, 5Part 4: Chloroacetylated derivatives of dextran, Cellul. Chem. Technol. 26 (1992) 675. Reaction of mesyl chloride with pullulan (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 241 (1996), S. 1-10 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Reaktion von Mesylchlorid mit vernetzten Pullulan-Mikropartikeln wurde untersucht, insbesondere der Einfluß der Reaktionsbedingungen auf das Produktverhältnis Chlordeoxy-/O-Mesylpullulan. In N,N-Dimethylformamid wird vorwiegend Chlordeoxypullulan gebildet, während in Pyridin bei niedrigen Temperaturen der Mesylester das Hauptprodukt ist. In N,N-Dimethylacetamide entstehen Chlordeoxy und Mesylgruppen im Verhältnis 2:1. Durch die Einführung der Chlordeoxy- bzw. Mesylgruppen werden die Mikropartikel hydrophob.
    Notes: The reaction of mesyl chloride with crosslinked pullulan microparticles was investigated, in particular the influence of the reaction conditions on the ratio between the two possible products chlorodeoxy or O-mesyl pullulan. It was found that in N,N-dimethylformamide the preponderent reaction product is chlorodeoxy pullulan, while in pyridine at low temperatures the main product is the mesyl ester of pullulan. In N,N-dimethylacetamide, the substituent groups are both chlorodeoxy and mesyl ones, in about 2:1 ratio. By the introduction of either chlorodeoxy or mesyl groups, the pullulan-crosslinked microparticles become hydrophobic.
    Additional Material: 8 Ill.
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    Structural analysis of poly(4-hydroxybutyl acrylate)-grafted silk fibres (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 241 (1996), S. 41-56 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(4-hydroxybutylacrylat) poly(4-HBA) wurde aus wäßrigem Medium mit Ammoniumpersulfat als Initiator auf Seide (bombyx mori) aufgepfropft. Die Gewichtszunahme stieg proportional mit der Monomerkonzentration im Pfropfsystem. Der Pfropfgrad lag im Bereich von 45 bis 65%. Die Feuchtigkeitsaufnahme nahm bei einer Gewichtszunahme von 〉10% stark ab. Die mechanischen Eigenschaften der Seidenfasern zeigten mit steigender Gewichtszunahme keine wesentliche Änderung. Doppelbrechung und isotroper Brechungsindex nahmen bis zu einer Gewichtszunahme von 35% ab und blieben dann unverändert. Röntgenbeugungsdiagramme zeigten, daß die kristalline Struktur durch die Pfropfbehandlung nicht modifiziert wird. Kalorimetrische (DSC), thermomechanische (TMA) und thermogravimetrische (TG) Analysen ergaben, daß das thermische Verhalten der poly(4-HBA)-gepfropften Seidenfasern nur leicht verändert wird. Die zur Bestimmung des dynamisch-mechanischen Verhaltens der Seidenfasern durchgeführten DMA-Messungen zeigten eine Verschiebung der E′- und E″-Modulspitzen zu niedrigeren Temperaturen mit steigender Gewichtszunahme. Ablagerungen auf der Faseroberfläche der bei einem hohen Monomer/Seide-Verhältnis (〉50%) gepfropften Seide wurden mit Rasterelektronenmikroskopie nachgewiesen.
    Notes: Poly(4-hydroxybutyl acrylate) poly(4-HBA) was graft-copolymerized onto silk fibres (bombyx mori) in aqueous medium with ammonium persulfate as initiator. The weight gain increased with increasing concentration of monomer in the grafting system. The grafting efficiency ranged from 45 to 65%. Equilibrium moisture regain decreased sharply beyond 10% weight gain. The tensile properties of the silk fibres did not change significantly as a function of the increasing weight gain. Birefringence and isotropic refractive index decreased until 35% weight gain and then remained unchanged. The X-ray diffraction patterns showed that the crystalline structure was not affected by grafting. Differential scanning calorimetry (DSC), thermomechanical (TMA), and thermogravimetric (TG) measurements showed that poly(4-HBA)-grafted silk fibres underwent only slight changes in the thermal behaviour. The dynamic mechanical measurements (DMA) exhibited a downward shift of both the storage (E′) and loss modulus peak (E″) with increasing weight gain. Scanning electron microscopy (SEM) observations showed the presence of some deposits adhering to the surface of silk fibres grafted at high monomer/silk ratio (〉50%).
    Additional Material: 7 Ill.
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    Effect of temperature and pH on the β-helix transition of poly(L-lysine) in sodium dodecyl sulfate solution (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1841-1846 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational phase diagram of poly(L-lysine) (4.6 × 10-4 M, residue) in sodium dodecyl sulfate (1.6 × 10-2 M) solution was constructed from circular dichroism results at various temperatures and pH's. Poly(L-lysine)-sodium dodecyl sulfate complexes undergo a β-helix transition upon raising the pH of the solution. The transition pH tends to shift downward at elevated temperatures. No helix-β transition can be detected for poly(L-lysine) in sodium dodecyl sulfate solution (pH 〉 11) even after 1-hr heating at 70°C. This is in marked contrast with uncharged poly(L-lysine) solution without sodium dodecyl sulfate, which is converted into the β-form upon mild heating of the solution above 50°C.
    Additional Material: 3 Ill.
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    Infrared and Raman spectroscopy of carbohydrates. Part VI: Normal coordinate analysis of V-amylose (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1885-1903 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A normal coordinate analysis of V-amylose has been performed for an isolated 61 helical chain. Negligible splitting from interactions of vibrations of successive residues is expected between A and E vibrational species due to the large size of the monomer unit. As a result, calculation of only the totally symmetric A modes represents an adequate approximation to the vibrational spectrum of helical polysaccharides. Using this method together with a valence force field we have obtained good agreement between the observed and calculated frequencies. In addition, the computed potential energy distribution and Cartesian displacement coordinates match previous experimental assignments, based on deuterium exchange. The analysis also supports the proposed mechanism for conversion of V-amylose to the more extended B-form. This conversion results in an observed frequency shift for the Raman line at 946 cm-1 which is predicted by the calculations.
    Additional Material: 6 Ill.
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    Estimation of the circular dichroism exhibited by statistical coils of poly(L-alanine) and unionized poly(L-lysine) in water (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2025-2033 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism of Ac-(Ala)x-OMe and H-Lys-(Lys)x-OH with x = 1, 2, 3, and 4 has been measured in aqueous solutions. The oligomers with x = 4 show similar circular dichroism spectra in water when the lysyl amino groups are protonated, and they respond in similar fashion to heating and to sodium perchlorate. Both oligomers at 15°C exhibit a positive circular dichroism band at 217-218 nm, which is eliminated by the isothermal addition of 4 M sodium perchlorate or by heating. The positive circular dichroism of the lysine oligomer is also eliminated when the pH is elevated to deprotonate the amino groups. Positive circular dichroism is still observed for Ac-(Ala)4-OMe at elevated pH. Circular dichroism spectra have been estimated for poly(L-alanine) and poly(L-lysine) as statistical coils under the above conditions, based on the trends established with the oligomers. Poly(L-lysine) and poly(L-alanine) are predicted to exhibit similar circular dichroism behavior in aqueous solution so long as the lysyl amino groups are protonated. The circular dichroism of the statistical coil of poly(L-lysine), but not poly(L-alanine), is predicted to change when the pH is elevated sufficiently to deprotonate the lysyl amino groups. These results suggest that the unionized lysyl side chains participate in interactions that are not available to poly(L-alanine). Hydrophobic interactions may occur between the unionized lysyl side chains. Protonation of the lysyl amino groups is proposed to disrupt these interactions, causing poly(L-alanine) and protonated poly(L-lysine) to have similar circular dichroism properties.
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    Studies on cytochrome c. X. Synthesis of Nα-benzyloxycarbonyl-[Thr107]-dotetracontapeptide (sequence 67-108) of baker's yeast iso-1-cytochrome cDedicated to late Prof. Ernesto Scoffone in grateful memory.For the previous paper in this series see Moroder, L., Borin, G., Marchiori, F. & Scoffone, E. (1974) Liebigs Ann. Chem. 213-224. A preliminary communication of some of the results presented in this paper has appeared: Moroder, L., Borin, G., Filippi, B. & Marchiori, F. (1974) in Peptides 1974, in press. The amino acid residues are of L-configuration. For a simpler description the customary L-designation for individual amino acid residues is omitted. Standard abbreviations for amino acid derivatives and peptides are used according to the IUPAC-IUB Commission on Biochemical Nomenclature (1972) Biochemistry 11, 1726-1732. (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2061-2074 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of nonapeptide hydrazide (sequence 93-101), [Thr107]-decapeptide (sequence 99-108), [Thr107]-tridecapeptide (sequence 96-108), [Thr107]-hexadecapeptide (sequence 93-108), [Thr107]-heptacosapeptide (sequence 82-108), and Nα-benzyloxycarbonyl-[Thr107]-dotetracontapeptide (sequence 67-108) of the proposed primary structure of baker's yeast iso-1-cytochrome c are described. Evidence is presented to indicate that these materials are sequentially homogeneous.
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    Raman spectroscopic study of poly (β-benzyl-L-aspartate) and sequential polypeptides (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2115-2135 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly-β-benzyl-L-aspartate (poly[Asp(OBzl)]) forms either a lefthanded α-helix, β-sheet, ω-helix, or random coil under appropriate conditions. In this paper the Raman spectra of the above poly[Asp(OBzl)] conformations are compared. The Raman active amide I line shifts from 1663 cm-1 to 1679 cm-1 upon thermal conversion of poly[Asp(OBzl)] from the α-helical to β-sheet conformation while an intense line appearing at 890 cm-1 in the spectrum of the α-helix decreases in intensity. The 890 cm-1 line also displays weak intensity when the polymer is dissolved in chloroform-dichloroacetic acid solution and therefore is converted to the random coil. This line probably arises from a skeletal vibration and is expected to be conformationally sensitive. Similar behavior in the intensity of skeletal vibrations is discussed for other polypeptides undergoing conformational transitions.The Raman spectra of two cross-β-sheet copolypeptides, poly(Ala-Gly) and poly(Ser-Gly), are examined. These sequential polypeptides are model compounds for the crystalline regions of Bombyx mori silk fibroin which forms an extensive β-sheet structure. The amide I, III, and skeletal vibrations appeared in the Raman spectra of these polypeptides at the frequencies and intensities associated with β-sheet homopolypeptides. Since the sequential copolypeptides are intermediate in complexity between the homopolypeptides and the proteins, these results indicate that Raman structure-frequency correlations obtained from homopolypeptide studies can now be applied to protein spectra with greater confidence.The perturbation scheme developed by Krimm and Abe for explaining the frequency splitting of the amide I vibrations in β-sheet polyglycine is applied to poly(L-valine), poly-(Ala-Gly), poly(Ser-Gly), and poly[Asp(OBzl)]. The value of the “unperturbed” frequency, V0, for poly[Asp(OBzl)] was significantly greater than the corresponding values for the other polypeptides. A structural origin for this difference may be displacement of adjacent hydrogen-bonded chains relative to the standard β-sheet conformation.
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    Masthead (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975) 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/bip.1975.360141101
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    Studies on cytochrome c. XI. Circular dichroism studies on synthetic peptides related to the C-terminal region of baker's yeast iso-1-cytochrome c (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2075-2093 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Circular dichroism studies on synthetic peptides related to the C-terminal region of yeast iso-1-cytochrome c were carried out and compared with conformational studies on horse cytochrome c fragments. Evidence is presented for a weaker predisposition for ordered structure in the former peptides when compared with the corresponding region in horse cytochrome c. These findings agree with theoretical predictions and with observations that yeast and other mammalian type cytochromes c differ in several minor respects.
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    Helix-coil transition kinetics in aqueous poly(α,L-glutamic acid) (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2107-2114 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A polarimetric electric-field-jump relaxation apparatus is described and used to determine the relaxation spectrum for the helix-coil transition of poly(α,L-glutamic acid) in water at 24°C. A maximum relaxation time of 1.7 μc occurs at the transition midpoint (pH = 5.9) yielding a rate constant for helical growth of 6 × 107 sec-1.
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    The interaction between two oppositely charged polyelectrolytes (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2181-2195 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mixtures of a weak polybase (polyethylenimine) and a weak polyacid acrylamide-acrylic acid copolymer in aqueous solutions at several ionic strengths and polymer concentrations are studied potentiometrically. When the concentrations of the polyethylenimine and acrylamide-acrylic acid copolymer charges are not too different, phase separation into two liquid phases (“complex coacervation”) is observed. In the pH region where no phase separation occurs, potentiometric titrations are performed on mixtures of both polymers. From the titrations of polyethylenimine solutions, acrylamide-acrylic acid copolymer solutions, and the mixtures, the free energy of interaction has been evaluated according to the theory of Litan. The dependence of the free energy of interaction on pH, polymer concentrations, and ionic strength is explained quantitatively with a model of cooperative electrostatic physical association.
    Additional Material: 6 Ill.
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    Investigation of fibrous structures. II. General method for the elucidation of the conformations of the complementary nucleic acids (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2231-2246 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problem of deducing the DNA structure with correct base pairing and specific symmetry is formulated in the form of algebraic equations. In this way the number of independent variables determining double-helix conformation can be reduced from six to four. The effectiveness of the method is illustrated by the computations for A-DNA and B-DNA. The method allows one to predict all possible conformations of the complementary nucleic acids.
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    Synthesis of sequential polypeptides containing L-azetidine-2-carboxylic acid residues (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2211-2230 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterization of a series of sequential polypeptides with the repeating sequences Aze-Pro-Aze, Pro-Aze-Pro, Pro-Aze-Gly, Aze-Pro-Gly, Ala-Aze-Gly, Aze-Ala-Gly, and Pro-Pro-Gly are reported. The polymers were prepared by the active ester method, using the p-nitrophenyl, pentachlorophenyl, and N-hydroxysuccinimide esters as the polymerizable tripeptide derivatives. Except for poly(Ala-Aze-Gly) obtained via the N-hydroxysuccinimide ester, all polymers were isolated in good yields and have weight-average molecular weights in the range 10,000-30,000. The molecular weights have been determined by applying the calibrated gel chromatography system described by Fairweather et al. [J. Chromatogr. (1972) 67, 157] and by viscometry. All di- and tripeptide intermediates were chemically and optically pure.
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    A triple-helical model for (Gly-Pro-Hyp)n with cis peptide unitsContribution 60 from the Molecular Biophysics Unit, Indian Institute of Science. (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2457-2466 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthetic regular polytripeptides of the type (Gly-R2-R3) where R2, R3, or both, are imino acids have been widely studied as model compounds for collagen. One such polytripeptide is poly(Gly-Pro-Hyp), since triplets with this sequence constitute about 10% of collagen. Recently, a new model has been proposed for this polytripeptide in which one of the three peptide bonds in the tripeptide unit is in the cis conformation, and the γ-hydroxyl group of hydroxyproline forms a direct interchain hydrogen bond within the triple helix. We have confirmed this structure by model building using computer techniques, and the helical parameters obtained by us are close to the experimentally observed values. The model is also found to be comparable in stability with other models from energy considerations.
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    Low Values of the Scheraga-Mandelkern β parameter for proteins. An explanation based on porous sphere hydrodynamics (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2479-2487 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several globular proteins have values of the Scheraga-Mandelkern β parameter significantly below the theoretical minimum value, β0 = 2.112 × 106, for an impermeable sphere. Using the Felderhof-Deutch generalization of the Debye-Bueche-Brinkman theory of hydrodynamics of porous spheres, we have shown that values of β slightly below this supposed minimum are theoretically expected. A porous sphere of uniform density has a minimum β of 2.084 × 106 at a Debye shielding ratio of 6.5, corresponding, for example, to a sphere radius of 11 Å and an inverse hydrodynamic shielding length of 0.6 Å-1, values not far from those of small proteins. A two-layer porous sphere model gives similar results. Although this is the first theoretical explanation of values of β below β0, the theory is incomplete since β values as low as 2.03 × 106 are observed.
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    Determination of the relaxation time of the helix-coil transition of poly(γ-benzyl-L-glutamate) by the nmr technique (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2489-2506 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: NMR measurements of poly(γ-benzyl-L-glutamate) are reported in several different strengths of magnetic field to determine the relaxation time of the helix-coil transition. Nmr spectra of various samples had line shapes varying from the double to single, depending on the extent of the polydispersity of the sample. This result indicated that the correct line shape of a polypeptide is obscured in the overlapping of multipeaks, which are due to the heterogeneity of the molecular weight in the sample. Thus, the conventional line-shape analysis could not be applied to the kinetic study of the helix-coil transition of polypeptides without consideration of this polydispersity effect on the line shape.To overcome this difficulty, we measured linewidths of nmr spectra for fairly monodisperse samples, using various nmr spectrometers, having field strengths from 60 to 220 MHz. The results were analyzed by a quadratic equation, which involves an additional term proportional to the frequency difference of two sites. The equation differs from the conventional quadratic equation, usually utilized in the case of the fast-exchange limit, only in this additional term. This modification is required to evaluate correctly the unusual broadening of the linewidth resulting from the polydispersity effect and to determine the relaxation time reflected in nmr.Nmr spectra of three samples (DP-35, 85, and 250) were measured by 220-, 100-, and 60-MHz spectrometers in trifluoroacetic acid/chloroform at 28°C and linewidths were analyzed. Relaxation times of the helix-coil transition obtained at the transition midpoint are 2.5 × 10-4, 7 × 10-4, and 1.1 × 10-3 sec, for DP-35, 85, and 250, respectively.
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    Polarized fluorescence in an electric field. A model calculation with application to the geometry of the 2-hydroxy-4,4′-diamidinostilbene-DNA complex (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2537-2553 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Theoretical expressions are derived for the change in the polarized components of the fluorescence, resulting from the orientation of a rigid molecule bearing a chromophore with arbitrary angles for the absorption and transition moments \documentclass{article}\pagestyle{empty}\begin{document}$ \vec \mu _a $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ \vec \mu _e $\end{document} with respect to the molecular axis. The break in the symmetry relation HV = VH is related to the tilt angle between \documentclass{article}\pagestyle{empty}\begin{document}$ \vec \mu _a $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ \vec \mu _e $\end{document}. The theory is applied to a sonicated DNA-2-hydroxy-4,4′-diamidinostilbene complex, in the blue and red emission bands of this peculiar dye. Simultaneous measurements of linear dichroism and fluorescence lead to the determination of an angle of 47° between a fluorescent bound dye and the DNA axis, with no difference for the blue- and red-emitting species, but confirm the presence of nonfluorescent bound dye in a more perpendicular arrangement.
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    Frictional properties of multisubunit structures (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2613-2623 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The translational drag, rotational drag, and intrinsic viscosity of spherical multisubunit structures have been calculated analytically using the Felderhof-Deutch theory of polymer frictional properties. The structures considered were hollow shells, spheres with uniform subunit density, and spheres covered with a subunit layer of different density. Changes in the transport coefficients resulting from the random removal of subunits and from the variation of subunit size are calculated. For the case of the shell, the results agree with the numerical computations of Bloomfield, Dalton, and Van Holde [Biopolymers 5, 135, 149 (1967)].
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    The interaction of glutaraldehyde with poly(α,L-lysine), n-butylamine, and collagen. II. Hydrodynamic, electron microscopic, and optical investigations on the reaction products (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2599-2612 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interactions of glutaraldehyde with either n-butylamine, poly(α,L-lysine), or collagen resulted in a fast release of protons in dilute aqueous solutions at various pH values, followed by much slower changes. The latter reactions, which extended over hours and days, were followed spectrophotometrically and revealed the formation of distinct absorption bands in the visible and near-ultraviolet regions in all the above systems. The visible-range bands disappeared upon treatment with sodium borohydride. A qualitative relationship between oxygen uptake by the system n-butylamine-glutaraldehyde and the slow formation of colored products has been established, while the chemical nature of the reaction products has not been determined.Sedimentation velocity, viscosity, and optical rotation measurements on the products of interaction between poly(L-lysine) and glutaraldehyde in aqueous solution indicated large conformational changes in the polyamino acid present in excess (in residues) over the dialdehyde. In particular, the intrinsic viscosity dropped considerably after interaction, indicating intramolecular crosslinking. At molar ratios of 1:1 between polylsine residues and aldehyde groups, intermolecular crosslinking of polylysine was obtained at pH 8.6.Electron microscopic examinations of collagen samples treated by glutaraldehyde at various pH values indicated changes from unordered to more ordered structures upon treatment with glutaraldehyde, in particular at pH 10.The present structural and optical investigations are considered to be relevant to tanning processes of hides and to fixation procedures.
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    The A and B conformations of DNA and RNA subunits. Potential energy calculations for dGpdC (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2625-2637 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to obtain a molecular picture of the A and B forms of a DNA subunit, potential energy calculations have been made for dGpdC with C(3′)-endo and C(2′)-endo [or C(3′)-exo] sugar puckerings. These are compared with results for GpC. The global minima for dGpdC and GpC are almost identical. They are like A-form duplex DNA and RNA, respectively, with bases anti, the ω′, ω angle pair near 300°, 280°, and sugar pucker C(3′)-endo. For dGpdC, a B-form helical conformer, with sugar pucker C(2′)-endo and ω′ = 257°, ω = 298°, is found only 0.4 kcal/mol above the global minimum. A second low-energy conformation (2.3 kcal/mol) has ω′ = 263°, ω = 158° and ψ near 180°. This has dihedral angles like the original Watson-Crick model of the double helix. In contrast, for GpC, the C(2′)-endo B form is 6.9 kcal/mol above the global minimum. These theoretical results are consistent with experimental studies on DNA and RNA fibers. DNA fibers exist in both A and B forms, while RNA fibers generally assume only the A form. A low-energy conformation unlike the A or B forms was found for both dGpdC and GpC when the sugars were C(3′)-endo. This conformation - ω′,ω near 20°,80° - was not observed for C(2′)-endo dGpdC. Energy surface maps in the ω′,ω plane showed that C(2′)-endo dGpdC has one low-energy valley. It is in the B-form helical region (ω′ ∼ 260°, ω ∼ 300). When the sugar pucker is C(3′)-endo, dGpdC has two low-energy regions: the A-form helical region and the region with the minimum at ω′ = 16°, ω = 85°.
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    Studies of the conformation of apomyoglobin in aqueous solutions and denaturing organic solvents (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 319-334 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The properties of apomyoglobin were examined in aqueous solutions and various helix- and random-coil-forming solvents by solvent perturbation, optical rotation, circular dichroism, and viscosity measurements. The solvent perturbation data obtained in neutral aqueous solutions suggest 25-40% exposure of the two tryptophyl residues and 50-60% exposure of the three tyrosyls. The estimates of burial of these groups are in the ranges expected for myoglobin based on its X-ray structure. In the helicogenic alcohols, methanol, ethanol, 2-chloroethanol, trifluoroethanol, and 1-propyl alcohol, as well as in acidic solutions, 8 M urea and 6M guanidine hydrochloride, essentially all the tryptophyl and tyrosyl residues are found to be exposed to solvent based on this method. Analysis of the ORD and CD data indicates that in the alcohols the α-helix content of apomyoglobin has in most cases changed from 58-59% to about 80-95%. Analysis of the intrinsic viscosity data based on the equations of Simha and Kirkwood and Auer indicates that the polypeptide chain in these solvents has the dimensions of fully extended α-helical rods, with lengths of 221-251 Å and mean diameters of 12.8-13.6 Å. It is concluded that apomyoglobin in the various alcohols must have an extended but somewhat irregular rodlike structure, having a few bend or irregular sequences between the α-helical segments due largely to the presence of the four proline residues, 37, 88, 100, and 120 in the amino acid sequence.
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    Static and dynamic quenching of protein fluorescence. I. Bovine serum albumin (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 335-351 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The fluorescence parameters, lifetime, relative quantum yield, maximum and mean wavelength, half-width, and polarization, of bovine serum albumin (BSA) were measured at 15°C in aqueous solutions containing varying concentrations of different chemical perturbants, glycerol, Cu2+ ions, guanidine hydrochloride, and urea. By considering a quenching mechanism as being either dynamic or static, depending upon whether the quenching is or is not accompanied by a change in the fluorescence lifetime, we were able to correlate the changes produced in the various fluorescence parameters by the different chemical perturbants with changes in macromolecular structure as the concentration of perturbant was gradually increased. The addition of glycerol and of Cu2+ ions indicated that in aqueous BSA both tryptophan residues are below the surface of the macromolecule, out of contact with solvent water, and, as a consequence, they are statically quenched. “Ultra-Pure” guanidine hydrochloride at 2.4 M or more caused a drastic conformation change, which resulted in the emergence of a visible tyrosine peak at 304 nm in the BSA fluorescence spectrum when either 260- or 270-nm excitation was employed. With the same excitation, the enhancement of BSA tyrosine fluorescence by 6-8 M ultra-pure urea produced only a shoulder near 304 nm in the BSA fluorescence spectrum. We have introduced the use of a new relative quantum yield for protein fluorescence, q′, referenced to the quantum yield of unquenched free tryptophan, which eliminates the quenching action of water from the reference.
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    Infinite-dilution viscoelastic properties of tobacco mosaic virus (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 409-417 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The storage and loss shear moduli, G′ and G″, have been measured for dilute solutions of unaggregated and aggregated tobacco mosaic virus samples in glycerol-water mixtures, by the Birnboim-Schrag multiple-lumped resonator modified for use with aqueous solvents. The frequency range was 100-5800 Hz, the concentration range 0.6-2.1 × 10-3 g/ml, and the temperatures 25.0° and 37.8°C. The number-average and weight-average molecular weights of the aggregated sample were estimated as 1.4 and 2.0 × 108, respectively, from electron microscopy. The extrapolated intrinsic moduli [G′] and [G″] were compared with the predictions of the Kirkwood-Auer theory for rigid rodlike molecules. For the unaggregated sample, the frequency dependence of [G′] and [G″] agreed well with the theory assuming the intrinsic viscosity to be 27 ml/g, though the asymptotic limit of [G′]M/RT at higher frequencies was slightly larger than the theoretical value of 3/5. For the aggregated sample, the data agreed with theory for rigid rods as modified to account for molecular-weight distribution.
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    New structures of LD-alternating polypeptides in solution and in the solid state (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1109-1114 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 6 Ill.
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    Masthead (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975) 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/bip.1975.360140601
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    Ion-polyelectrolyte interactions. Comparison between Manning's electrostatic theory and the multiple equilibrium theory of Scatchard in the case of linear polyelectrolytes and bivalent counterions (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1115-1120 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Manning's and Scatchard's models for the description of ion-polyelectrolyte interactions are compared in the case of linear polyelectrolytes and bivalent counterions, where “condensation” of the counterions is known to occur for certain concentration ratios of the two species in solution. This comparison leads to the definition of certain conditions on Scatchard's parameters for a precise structural interpretation of Scatchard's plots to be valid. Experimental data obtained with both models are compared and found in good agreement under such conditions.
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    A theoretical estimate of the energy barriers between stable conformations of the proline dimer (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1121-1132 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Semi-empirical energy calculations for an internal Pro-Pro dimer are presented that take into account the nature of the flexibility of the proline ring due to its puckering. Calculations show that three stable conformations are available for the dimer: the cis (ω = 0°, ψ = 160°); the trans (ω = 180°, ψ = 160°, also referred to as trans′); and the cis′ (ω = 180°, ψ = -40°) conformations. The best conformational pathways between these stable conformations are determined. Calculations also show that the barrier for cis′-trans′ conversion is of the same order of magnitude as that for cis-trans conversion.
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    On the application of polyelectrolyte limiting laws to the helix-coil transition of DNA. III. Dependence of helix stability on excess univalent salt and on polynucleotide phosphate concentration for variable equivalent ratios of divalent metal ion to phosphate (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1407-1422 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using the free energy difference between double-helix and random-coil forms of DNA as a measure of the stability of the double helix, we calculate the dependence of the stability on excess univalent cation concentration and on polynucleotide phosphate concentration, both as functions of the equivalent ratio r of divalent cation-to-phosphate concentrations. The theoretical tool is merely to compare the free energy of one polyelectrolyte solution, characterized by the polyelectrolyte linear charge density, with the free energy of another, characterized by a different value of the charge density. It is assumed only that the charge density of the double helix is greater than that of the coil form. The calculation represents the only molecular theory given to date (for r ≠ O) for these aspects of helix stability.We find that, as excess univalent cation concentration increases, the helix stability increases if r is small but decreases if r is large (i.e., of the order of unity). Moreover, as the concentration of nucleotide phosphate increases, the helix stability does not change for small values of r but increases for large values. For both effects, a continuous transition as a function of r bridges the low-r and high-r behaviour.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140708
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    Base pairing of adenine and uracil derivatives in the presence of water (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1423-1435 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The association of chloroform-soluble derivatives of uracil and adenine has been examined in chloroform solution in the presence of dissolved water. Analysis by infrared spectroscopy shows that complex formation still occurs in these conditions, and that the extent of association is substantially unchanged by the presence of water. Evidence is presented for the coexistence of two kinds of base pair (involving, respectively, the C2 and C4 carbonyl groups of the pyrimidine) in the solutions, and for some displacement in their relative balance by the added water. The binding of water to the C2 and C4 carbonyl groups can be separately observed in both the free uracil derivative and its 1:1 complex with 9-ethyladenine. Little or no competition has been found to occur between the formation of base pairs and binding of water to the bases, as judged by measurements of water solubility in chloroform solutions of the bases individually and in 1:1 mixtures. The evidence suggests that this phenomenon can be largely explained by the formation of double hydrogen bonds by the uracil carbonyl groups. Taken together with recent published observations, the results indicate that hydrogen bonding may make a much greater energetic contribution to conformational stability of biopolymers in aqueous solution that has been supposed.
    Additional Material: 7 Ill.
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  • 87
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    Synthesis and characterization of stereoregular poly(D-methionyl-L-methionine) and poly(L-methionyl-D-methionyl-L-methionine) (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1437-1446 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By use of a polycondensation procedure free of racemization, stereoregular polymethionines have been synthesized from C-activated D-methionyl-L-methionine and L-methionyl-D-methionyl-L-methionine.The poly(D-methionyl-L-methionine) and poly(L-methionyl-D-methionyl-L-methionine) so prepared are soluble in chloroform and can be purified through dissolution in this solvent and precipitation by ligroin.Poly(D-Met-L-Met)which is obtained in a 25% yield, is about 5000 in average molecular weight. It has no discernible optical activity when examined between 400 and 600 nm in a trifluoroacetic acid solution.Poly(L-Met-D-Met-L-Met) (40% yield, M. W. = 10,000) is an optically active polymer. [α]43624 ≈ + 170° for a chloroformic solution (c = 0.2 CHCl3).
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  • 88
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    On the parameters of DNA melting curves in the low Na+ ion concentration range (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1551-1552 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140719
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    Masthead (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140801
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  • 90
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    Refinement of the structure of β-chitin (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1581-1595 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure of β-chitin has been refined by rigid-body least-squares methods, based on the intensity data for highly crystalline specimens from the pogonophore Oligobrachia ivanovi. The structure consists of an array of poly-N-acetyl-D-glucosamine chains all having the same sense, which are linked together in sheets by N—H … O=C hydrogen bonding of the amide groups. In addition to the O-3′—H … O-5 intramolecular hydrogen bond, analogous to that in cellulose, the CH2OH side chain forms an intrasheet hydrogen bond to the carbonyl oxygen on the next chain. This structure shows considerably better agreement between observed and calculated intensities than that possessing an intersheet hydrogen bond, as had been proposed previously. The structure is consistent with the swelling properties of β-chitin and can also be seen to be analogous to that of native cellulose.
    Additional Material: 4 Ill.
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  • 91
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    Analyse conformationnelle de la N-méthylamide de l'acide L-pyroglutamique par diffusion Rayleigh depolarisée, spectroscopie de vibration et calcul de l'energie conformationnelle (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1565-1579 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational analysis of N-methylamide of pyroglutamic acid has been performed by theoretical energy calculations and experimental physical techniques, namely, laser Raman spectroscopy and depolarized Rayleigh scattering. The two theoretically predicted conformations are evidenced in crystalline state (ψ1 = +169°) and in aqueous solution (ψ1 ≃ -20°). This study confirms the interest of a careful vibrational analysis of peptides and N-deuterated derivatives for providing an estimate of the dihedral angle ψ. The relationship between amide III frequency and ψ values is emphasized.
    Additional Material: 8 Ill.
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  • 92
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    Adsorption behaviour of globular proteins at the water/mercury interface (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1553-1563 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The adsorption of globular proteins at solid/liquid or liquid/liquid interfaces provides evidence of unfolded molecular conformation. Proteins with high apolar character are strongly unfolded, while those with high polar character are generally incompletely unfolded. Structural changes of globular proteins at adsorption on mercury electrodes were studied by ac polarography and capacity-time curves. The surface area per molecule of nine globular proteins was determined from the adsorption kinetics at the dropping mercury electrode. For all the proteins investigated, this value was greater than the maximal molecular cross section of the native proteins. The surface area was about 19 Å2 per amino acid residue, which coincides with the value for unfolded proteins at the water/air interface. Differences between dropping mercury electrode and hanging drop mercury electrode occurred only with lysozyme and phosphorylase; for the other proteins, the structure of the adsorption layer was independent of the time of interaction at the electrode. Since not all of the reducible groups of the adsorbed proteins come into contact with the electrode, the flattening should be incomplete.
    Additional Material: 5 Ill.
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  • 93
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    Classical potential energy calculations for ApA, CpC, GpG, and UpU. The influence of the bases on RNA subunit conformations (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1597-1613 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Classical potential energy calculations have been made for the ribodinucleoside monophosphates ApA, CpC, GpG, and UpU. Van der Waal's, electrostatic, and torsional contributions to the energy were calculated, and the energy was minimized with the seven backbone conformational angles as simultaneously variable parameters. At the global minimum, ApA and CpC have conformations like double helical RNA: the angles ω′ and ω are g-g-, the sugar pucker is C3′-endo, and the bases are anti. GpG and UpU, on the other hand, have the ω′,ω angle pair g-t at the global minimum, and for GpG the bases are syn. Energy contour maps for ω′ and ω show two broad, low energy regions for ApA, CpC, and UpU: one is g-g-, and the second encompasses g-t and g+g+ within a single lowenergy contour. The two regions are connected by a path at 10-13 kcal./mole. For GpG, with bases syn, however, only a small low-energy region at g-t is found. The helical ‘A’ RNA conformation is 8.5 kcal/mole higher for this molecule. Thus, the base composition is shown to influence the conformations adopted by dinucleoside phosphates. Comparison of calculations with experimetal data, where available, show good agreement.
    Additional Material: 6 Ill.
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    A vibrational study of poly (L-proline) I and II in the far infrared (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1615-1622 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The far infrared spectra of poly(L-proline) I (190-35 cm-1) and II (400-35 cm-1) were obtained in the solid state at both 300° and 110°K. A significant difference in the region below 100 cm-1 was observed. A very intense band located at 60 cm-1 in the infrared spectrum of form II has no counterpart in form I. This indicates the sensitivity of low-frequency vibrations to the difference in conformation assumed by both forms in the solid state.Additional bands observed in this study are correlated with ir and Raman data previously reported and tentative assignments are made using the results of normal mode calculations (in the single-chain approximation) which have been reported.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140806
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    Potentiometric titrations involving the β-coil transition (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1623-1631 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Potentiometric titrations of poly(S-carboxymethyl-L-cysteine) and poly(S-carboxy-ethyl-L-cysteine) were carried out in aqueous sodium chloride solutions and in water. For samples of both polymers of high molecular weight, a new pattern was observed concerning the change of titration curve with time; the β-coil transition became sharper and the transition free energy increased by about 100 cal mole-1 as the equilibrium was approached. This suggests that equilibrium data were not obtained in most previous studies on the titration involving the β-coil transition. It also shows that the reversbility is not necessarily sufficient to confirm the equilibrium. Another pattern, which was previously observed, was also confirmed with a low molecular weight sample of poly(S-carboxymethytl-L-cysteine). The titration curves were shown to be insensitive to polymer concentration, even when aggregation or phase separation was present. The validity of the Gouy model to describe the titration curve of the β-structure was found to depend on molecular weight as well as on the nature of the side chain.
    Additional Material: 5 Ill.
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    The interaction of collagen with the hydrophobic fluorescent probe 2-p-toluidinylnaphthalene-6-sulfonate (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1651-1666 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three kinds of fluorescence enhancement result from the interaction of 2-p-toluidinylnaphthalene-6-sulfonate and calf-skin collagen. They are negatively cooperative, independent, and highly cooperative fluorescence enhancement. In the independent region at pH 3.7, the binding number is about 36 moles of 2-p-toluidinylnaphthalene-6-sulfonate per mole of tropocollagen with a binding constant of 2.0 × 104 M-1; with ΔG = -5.7 kcal/mole, ΔH = -4.0 kcal/mole, and ΔS = 6 e.u. The pH dependence of fluorescence of native collagen shows that the deprotonated forms of the β and γ carboxyl groups of aspartic and glutamic acid decrease the intensity, possibly by charge repulsion of the negatively charged sulfonate group of 2-p-toluidinylnaphthalene-6-sulfonate. The positive charge of lysine is found to be unimportant in the interaction of 2-p-toluidinylnaphthalene-6-sulfonate with collagen. Fluorescence enhancement is caused mainly by the hydrophobic interactions of 2-p-toluidinylnaphthalene-6-sulfonate and collagen. Salt bridge formation between basic and acidic side chains in very low salt concentration may be detectable by 2-p-toluidinylnaphthalene-6-sulfonate fluorescence.
    Additional Material: 9 Ill.
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    The random coil → β transition of copolymers of L-lysine and L-valine: Potentiometric titration and circular dichroism studiesThe abbreviations for amino acids and polymers conform to the tentative rules of the IUPAC-IUB Commission on Biochemical Nomenclature as published in Biochemistry 11, 942 (1972). CD, circular dichorism. DP, degree of polymerization.Publication No. 1012 of the Graduate Department of Biochemistry, Brandeis University, Waltham, Mass. 02154. (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1633-1649 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of copolymers of L-lysine and L-valine [poly(L-lysinef L-valine100-f)] containing 0-13% L-valine have been studied, in 0.10M KF solution, using potentiometric titration and circular dichroism spectroscopy. Incorporation of increasing amounts of valine into the copolymers favors β-sheet formation over α-helix formation at high pH and room temperature. The titrations were analyzed using the method of Zimm and Rice and the partial free energy (ΔG0cβ) for the coil-to-β-sheet transition for valine is estimated at 900 cal/mole at 25°C. From the temperature dependence of the free energy, the partial enthalpy, ΔH0cβ, and entropy, ΔS0cβ, of the transition for valine is estimated to be 854 cal/mole and 6.0 e.u., respectively. The corresponding partial thermodynamic parameters for L-lysine are in agreement with published results. The fraction of β-sheet versus pH has been calculated for poly(L-lysine86.8 L-valine13.2) at 25.0°C using the titration data; data obtained from circular dichroism spectroscopy for the same copolymer are in good accord. It is concluded from these results that L-valine is a very strong β-sheet forming amino acid. Furthermore, these results indicate that the Zimm-Rice method is applicable to transitions between the coil and β-sheet states for a polypeptide containing two different residues.
    Additional Material: 7 Ill.
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    Conformational analysis of polynucleotide chains. Double-stranded structures (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1667-1684 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational analysis of double-stranded helical polynucleotides was carried out in terms of internal and external parameters, using semiempirical energy potential functions. The results obtained show that the structures proposed on the basis of the X-ray analysis for A-DNA and RNA's are almost identical to those corresponding to the conformational energy minima, whereas that proposed for B-DNA still appears to suffer from conformational strains. On the other hand, the B-DNA structure theoretically predicted is stabilized by both van der Waals energy and possible specific interactions with water molecules and counterions. This may explain the stability of the B form with respect to the A form at high relative humidity and ion strength. A possible role of the A + T fraction in stabilizing the B-type DNA emerges in connection with its preferential ability to bind ions. This agrees with the results on the crystalline structures of GpC and ApU. For RNA's, the occurrence of only A-type structures is explained as being due to the C(3′)-endo puckering of ribose in a double helix.
    Additional Material: 13 Ill.
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    Sedimentation of generalized systems of interacting particles. I. Solution of systems of complete Lamm equations (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1685-1700 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A very general approach to the chemical equilibria between many interacting molecules during sedimentation (boundary, band, or active enzyme) taking into account boundary conditions, cell geometry, equilibrium constants, diffusion, enzyme kinetics, etc., is presented. Through a Fortran program, the method has been applied to two very simple but typical cases. With only minor adjustments, the method presented here for sedimentation studies can be extended to all sorts of problems in which “pools” of various species are interacting with each other.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bip.1975.360140811
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    Solid-state conformation of poly(O-benzyloxycarbonyl-L-tyrosine) (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1769-1772 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140816
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