ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

You have 0 saved results.
Mark results and click the "Add To Watchlist" link in order to add them to this list.
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Physics  (1,008)
  • 1980-1984  (1,008)
  • 1965-1969
  • 1982  (517)
  • 1981  (491)
  • 1
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1981-03-13
    Description: Great advances have been made in fundamental scientific research in recent years. The new knowledge gathered, in addition to deepening our understanding of the physical universe, contributes a range of abilities and opportunities to society that would not otherwise be available. Much research that may be called applied because it addresses needs of society is quite fundamental in character, and support of such research at the National Science Foundation is to be handled in tandem by the research directorates. Other areas that require a refocusing of support are engineering science and education, at all levels, in science and engineering. Increasing our strength in these areas is essential to achieve our national economic, social, and political goals. Steps are being taken by the National Science Foundation to make its structure better able to deal with engineering and applied research and to provide greater mutual reinforcement between applied and basic research.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Slaughter, J B -- New York, N.Y. -- Science. 1981 Mar 13;211(4487):1131-6.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7466384" target="_blank"〉PubMed〈/a〉
    Keywords: Cell Biology ; Chemical Phenomena ; Chemistry ; *Forecasting ; Geological Phenomena ; Geology ; *Government Agencies ; Molecular Biology ; Neurochemistry ; Physical Phenomena ; Physics ; Research Support as Topic ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 13-21 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is shown that the 13C NMR spectral collapse temperatures Tc reported by Axelson and Mandelkern tend to give a constant ratio of Tc/Tg averaging 1.21 ± 0.05 and independent of Tg or of polymer structure. It is further shown that Tc is not a high-frequency value for Tg because this would require Tc/Tg to decline with increasing Tg. Tc/Tg agrees in numerical value with Tu/Tg, where Tll is the liquid-liquid transition lying above Tg. Direct comparison of Tc and Tu for four polymers PIB, PnBA, atactic PP, and isotactic PMMA shows very close agreement. The various results suggest, but do not prove, that Tc from 13C NMR spectroscopy may be a new, direct measure for Tll. A measured Tc of 233K for linear PE is compatible with a Tg near 195 K (233/195 = 1.19), whereas a Tg of 148 K gives the ratio 233/148 = 1.57, which is outside any value shown in tabulated form.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 49-58 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A theory is presented to account for the effect of the impingement of growing spherulites on their Hv small-angle light scattering patterns. The theory is developed on the basis of results of computer-simulated two-dimensional spherulite growth and calculated scattered intensities. The impingement produces a lowering of the intensity of the scattering maximum and the diminishing of the overall sharpness of the scattering peak. The extent of these effects increases with area fraction of spherulites. A procedure is suggested for determining correction factors that may be applied to intensity data obtained during the course of spherulite crystallization. An interpretation is made of the type of average spherulite size determined from the scattering angle of maximum intensity.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 109-120 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Broad-line 1H NMR spectra of linear polyethylene at temperatures in the α-transition range can be analyzed in terms of contributions from the crystalline and noncrystalline components provided molecular motion in the crystalline region is adequately considered. The spectrum of solid n-C32H66 or n-C44H90 prior to melting is used to take account of the contribution of the crystalline region of the polymer to molecular motions. The temperature dependence of the component distribution in the polymer is briefly discussed for a wide range of temperatures, together with previously reported results at low temperatures. The noncrystalline component is in a rigid glassy state at very low temperatures but with rising temperature it transforms to a mobile glassy state with restricted molecular motion, and transforms partially to the rubbery state at high temperature. The crystalline component remains rigid at low temperature, but some molecular motion is associated with it at higher temperatures in the α-transition range.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 135-141 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The surface composition of TiCl3-based Ziegler - Natta catalysts prepared by various methods was analyzed by ESCA to correlate the total amount of surface titanium with the catalyst activity in propylene polymerization. The ESCA peak ratio (Ti 2P3/2/Cl 2P) of the catalysts was measured to estimate the surface composition. The titanium index defined as the product of the (Ti/Cl peak ratio and surface area) was closely correlated with the catalyst activity in polymerization. This indicates that surface titanium concentration and surface area determine the catalyst activity. It was also found that removal of surface aluminum and chlorine at the catalyst preparation stage results in concentration of titanium at the surface and an increase in surface area.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 181-184 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 185-186 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 245-252 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Adsorption of three copolymers of acrylic acid with N-1-naphthylacrylamide on monodisperse polystyrene latex was studied as a function of pH, ionic strength, and latex concentration. A comparison of the observed adsorptive capacities with predictions based on a model in which the adsorbed polymers retain their shape in solution showed that this model leads to an increasing underestimate as the density of the hydrophobic groups on the polymer is increased and as the pH is reduced.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 281-292 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is shown that in strictly alternating rigid-flexible copolyamides with the axial ratio x of their rigid elements between 3 and 3.5, lyotropic liquid crystallinity exists in solutions of 25-40% poiymer. For polymers having 4.0 〈 x 〈 4.5, anisotropic solutions appear in the concentration range 15-25%. These axial ratios are substantially smaller than the value of xc = 6.4 predicted by theories for independent rodlike particles, but are in qualitative agreement with recent theoretical calculations taking cognizance of the connection of rodlike elements by flexible residues in the polymer chain. It is further shown that solid solutions of a model compound in an alternating rigid-flexible polymer may be prepared, provided there exists shape and size similarity between the model compound and the polymeric repeat unit.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 321-334 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Optical-absorption, fluorescence, and Raman spectra for solutions, suspensions, and precipitates of poly(1,6-di-p-toluene sulfonoxy-2,4-hexadiyne) in and from nitrobenzene, acetone, and chloroform are presented. These are interpreted in terms of the occurrence of two forms of the polymer chain; a quasicrystalline form with properties close to those of single crystal polymer and a chain-extended form occurring in solution and colloidal particles, with an absorption energy of about 2.5 eV (20,000 cm-1). No evidence is found for the presence of very short polymer chains in partially polymerized monomer at low conversion. The relationship of these results to those for deformed single crystals is briefly discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 361-367 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of heterogeneous chlorination of high-density polyethylene on its crystalline regions was investigated by NMR, x-ray diffraction, differential scanning calorimetry, and infrared spectroscopy. Crystallites remained inaccessible to attack by chlorine, even after extensive chlorination, however, their perfection was affected by extensive chlorination of the adjacent amorphous regions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 369-370 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 405-421 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Partitioning of macromolecules between pore and bulk solutions directly affects both equilibrium and transport processes such as exclusion chromatography and movement of solutes through porous media. Because of interactions between macromolecules and the pore wall, the variation of the macromolecule activity with concentration is different inside the pore than in bulk solution. This difference causes a concentration dependence of the distribution coefficient, as reported in experiments involving exclusion chromatography. In order to explain this effect, we develop a model for a concentration-dependent distribution which explicitly accounts for a coupling between pore-macromolecule and macromolecule-macromolecule interactions. Predictions using this model are reported for the case of rigid spherical macromolecules in both cylindrical and slit pores, including both steric (hard sphere-hard wall) and long-range (screened electrostatic) interactions. An important result is the existence of a general correlation between the first order concentration effect and measurable properties of the macromolecule and porous medium.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 449-457 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A difference-spectrum method is used to measure vibrational frequency shifts in mechanically stressed polymers. It is shown that the peak-to-peak height of the difference-spectrum intensity profile is a linear function of small frequency shifts with a slope inversely proportional to the band halfwidth for Lorentzian or Gaussian bands. The method is applied to measure frequency shifts in uniaxially stressed ultraoriented isotactic polypropylene films, using a double beam infrared grating dispersion spectrometer with a nonstressed sample in the reference beam. It is shown that frequency shifts can be measured with an accuracy of better than 0.01 cm-1 using the difference-spectrum method.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 487-497 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The width at half-height of SAXS discrete diffraction peaks has been used to compute the number of polyethylene lamellae in a stack. The dependence of this width on diffraction order reflects the nature and magnitude of lattice fluctuations. Within the literature there have been conflicting reports on this order dependence and hence on the nature of the lattice fluctuations. Previous studies have neglected the effects of instrumental broadening. These present studies show that instrumental effects can account for some 40% of the observed first-order peak width and drastically change the ratio of peak widths as a function of order. These studies, carried out on isothermally grown polyethylene single-crystal mats, also demonstrate the importance of the functions chosen to represent the various broadening factors. A mat was made up consisting of randomly stacked lamella with two distinct fold periods. The scattering from this mixed mat could not be described by either of the prevailing theories.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 531-555 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Several choices of the functions describing the creation and destruction processes of entanglement junctions in the Yamamoto network theory of concentrated polymer solutions have been examined. These choices are simple functions of the extension of the network segments bridging the entanglement points and it is demonstrated that the moments of the distribution function describing the network conformation can be solved for analytically. This has been done for a wide range of two-dimensional flows, both for the steady state and transient start-up and relaxation problems. The macroscopic stress tensor and flow birefringence are calculated and a variety of nonlinear effects are predicted and discussed.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 517-527 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The shear stress σ, two components of birefringence, and extinction angle were measured for a concentrated polystyrene solution in step-shear deformation of magnitude of shear 0.3 ≤ γ ≤ 4.0. The stress-optical coefficient did not depend on either γ or time. The first and the second normal-stress differences v1 and v2 were evaluated with the use of the stress-optical law. Over a certain range of long times, σ could be factored as σ = γh(γ)G(t) and the quantity h(γ) agreed with the prediction of the Doi-Edwards theory based on the de Gennes tube model of entangled polymer chains. At short times the effect of γ on σ/γ was smaller than at long times. The relaxation spectrum became approximately independent of γ at the short-time end of the rubbery plateau region. The ratios v1/σ and v2/v1 were independent of time and were in quantitative agreement with those predicted by the Doi-Edwards theory: v1/σ was equal to γ, v2/v1 was negative, and |v2/v1| decreased with increasing γ.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 557-587 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The results of flow birefringence measurements are reported for polymer solutions of moderate concentration subjected to a wide range of two-dimensional flows. These flows were generated in a four-roll mill which enables one to systematically vary the ratio of the vorticity to the rate of strain in the flow while holding the velocity gradient constant. It is shown that steady-state birefringence data collected over a wide range of flow types can be correlated against the eigenvalue of the velocity gradient tensor, in agreement with criterion for strong and weak flows from model calculations. Transient birefringence measurements in which purely extensional flows were started from rest are also reported. It was observed that the birefringence went through a pronounced overshoot in time for two different polymer/solvent systems. Flow induced increases in the solution turbidity were also observed and the increased turbidity remained constant over a period of many hours after extensional flows were arrested. The birefringence, on the other hand, decayed to zero almost immediately after the flows were stopped. These changes in the turbidity suggest that crystallization of the polymer was occurring. The qualitative results of experiments are compared to recent network model calculations using the theory of Yamamoto for concentrated polymer systems. It is found that this model can predict qualitatively many of the experimental observations if the function describing the breakage of polymer chain entanglements is allowed to depend on the conformation of the polymer segments bridging the entanglements. In particular, this dependency of the entanglement breakage on the conformation of the network segments leads to a predicted overshoot of birefringence when purely extensional flows are started from rest. It is also demonstrated through this model that birefringence data taken over a wide range of flow types can be used to estimate the degree to which the network deforms affinely with the flow field.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 653-665 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: X-ray diffraction patterns were obtained for as-cast and oriented films of poly(γ-benzyl L-glutamate) and a comparison was made of the molecular packing of the α-helices in forms B and C. Form B snowed Bragg reflections on the layer lines as well as on the equator. The spacings were explained by a monoclinic unit cell comprising two chains, with a = 29.06 Å, b = 13 20 Å, c = 27.27 Å α = γ = 90°. and β = 96°. The chains contained in this unit cell and consequently alternating in the crystal have opposite chain directions. Form C showed continuous scattering on the layer lines and reflections on the equator. This form, therefore, is a nematiclike paracrystal in which the packing of α-helices is periodic in the direction lateral to the chain axis (a = 14.8-115.2 Å, b = 14.3-14.8 Å, c = 27 Å, and γ = 118°-120°), but the relative levels of the chains along the chain axes are displaced. The formation of form C may be attributed to random placement of two chains with mutually opposite chain directions.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 631-651 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The carbon-13 NMR linewidth (proton decoupled) of linear and branched polyethylenes crystallized so as to yield different supermolecular structures, as well as a polyethylene oxide sample, have been studied in detail. The purpose has been to assess the different molecular contributions to the linewidth in the completely amorphous polymer as well as in the amorphous regions of the semicrystalline state. These studies on a number of different structures were complemented by both proton-decoupled and dipolar-decoupled magic-angle spinning experiments on a particular sample, as well as frequency dependence studies. It is found that the abnormally broad resonance lines previously reported for the molten polymer can be significantly reduced by adopting appropriate methods of sample preparation and magnetic-field homogenization at each temperature. Relatively narrow lines result which can be interpreted in a conventional manner. In the semicrystalline state, the resonance lines are relatively broad and are shown to be morphology dependent. Specific contributions and their temperature dependence are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 689-701 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Molecular relaxations of polyesters containing C5-C15 rings in the main chain have been studied by DSC, dielectric dispersion, and NMR. Results are discussed in relation to the size and mobility of the rings. The Tg or α-relaxation peak moves to higher temperature with an increase in the ring size from C5 to C12, but the effect is accompanied by an even-odd alternation with ring size. The β relaxations in dielectric dispersion reflect local-mode motion of ester groups and are affected by steric interactions with the rings. Motions of the ring methylenes of C12 and C15 ring units are detected below Tg by broad-line NMR.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 731-741 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A computer program for modeling three-dimensional spherulite nucleation, growth, and impingement was elaborated. The Monte Carlo method was used to determine the degree of conversion and calculate the volume of the spherulites. Athermal, thermal, and mixed types of nucleation were tested. The experimental Avrami exponent agrees with the predictions for athermal and thermal nucleation while for mixed nucleation a nonintegral exponent is characteristic. The spherulite size distributions are very different from athermal and thermal nucleations. An intermediate pattern of distribution is proper for the mixed type of nucleation. The boundaries of the largest spherulites from thermal and mixed nucleation are concave while those of the smallest spherulites are convex.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 749-761 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Correlations of the stress-intensity factor K with crack speed a have been obtained for environmental stress cracking (ESC) of a series of low-density polyethylenes in detergent. In the majority of the materials, the crack speed increases initially with increasing K, then becomes constant, and finally starts decreasing. The ESC resistance increases with increasing molecular weight and, in general, the quenched materials show greater ESC resistance than slowly cooled ones. The crack propagation results agree well with the ESC model of Williams. Attempts have also been made to understand the micromechanics of ESC failure from a combined approach of K, the crack tip characteristics, and the fracture surface appearance. The roughness of the fracture surface increases with increasing K.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 803-814 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The NMR spin-spin relaxation (T2) spectra of high-density polyethylene (PE) has been investigated over a wide range of temperatures, both in the solid and molten states. Previous work in these laboratories has shown that the T2 relaxation spectrum of molten polyethylene differs from that of other polymers studied in that (a) it cannot be decomposed into two relaxation spectra (T2S and T2L) and (b) there is some evidence of a memory effect. This paper attempts to elucidate these observations, and compare them with the spin-spin relaxation of polyethylene at lower temperatures. In the solid state, the T2 decay comprises both a Gaussian distribution for the crystalline region, and an exponential decay for the amorphous component. The effects of crystallization conditions and of temperature were determined. In the molten state the T2 decay is more complex, but can be resolved into three exponentials. The longest (T2L) component arises as expected from the most mobile, low molecular weight fraction. The T2S component is due to an entangled but mobile network, as in other polymers. In addition, a short relaxation component T2X is observed, which is influenced by previous crystallinity and the processing history of the material, and is ascribed to some vestigial degree of structure in the molten phase.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 837-847 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polymerization of p-acryloyloxybenzoic acid by heating on a hot stage was previously reported to lead to a lyotropic mesophase. Using optical microscopy, thermal analysis, and infrared analysis, it was shown that this mesophase involves oligomers of poly(p-oxybenzoate) formed from the monomer by ester interchange through internal acidolysis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 877-888 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ultradrawing of films of high-molecular-weight polyethylene (M̄w = 1.5 × 106) produced by gelation crystallization from solution is discussed. The influence of the initial polymer volume fraction (φ) on the maximum draw ratio (λmax) of the dried films is examined in the temperature region from 90-130°C. The results can be described very well by the relation λmax = λmax1 φ-1/2 where λmax1 is the (temperature-dependent) maximum draw ratio of the melt-crystallized film. An attempt is made to discuss the marked influence of the initial polymer volume fraction on λmax in terms of the deformation of a network with entanglements acting as semipermanent crosslinks.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 863-875 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The persistence length of poly(terephthaloyl p-amino benzhydrazide) (X-500) in dimethyl sulfoxide (DMSO) has been determined from intrinsic viscosities measured for several whole-polymer samples. An approximate correction is applied for excluded volume effects, and these corrected values are fitted using the viscosity treatments of Yamakawa and Fujii and of Eizner and Ptitsyn. Both give for the persistence length of X-500 values in the range 30-35 Å. Revised treatment of our previous light scattering data for the same polymer yields 49 Å for the persistence length. Thus the chain extension of X-500 falls between those of para-linked polyamides and those of typical freely coiling macromolecules. Phase diagram studies indicate the solubility of X-500 in DMSO decreases with rising temperature, and can be increased by the addition of LiCl. No anisotropic phase is found in DMSO at the highest volume fraction of polymer, v2 = 0.19, which can be obtained with 4 g/dl LiCl. The critical concentration of X-500 needed for the appearance of the anisotropic phase depends upon solvent since Morgan reported an anisotropic phase for this polymer in 100% H2SO4 when v2 ≈ 0.13.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 921-932 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The flow field in an electrically driven jet has been examined and quantitatively analyzed. Using a model fluid, the nature of the streamlines and magnitude of the stream velocities were investigated with the aid of tracer particle photography. It was found that the velocity field is not purely extensional, but contains rotational components as well. Furthermore, the only portion of the jet completely free of any rotational component is the region about the symmetry axis. The extensional strain rate along the symmetry axis increases rapidly with the applied electric field intensity and can attain values in excess of 50 sec-1. This suggests that it might be possible to draw continuous oriented fibers from polymer melts by this technique if the jet can be operated at sufficiently high electric field intensity.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 983-989 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A cage model has been presented to describe the kinetics of recombination of radicals in solid polymer. The theory includes Torrey's treatment for jump diffusion and radiative boundary condition in the diffusion equation to account for the hindrance to the diffusion of macroradicals and the finite cage process of recombination reaction, respectively. The result has been applied to the interpretation of data on the decay of allyl radical in irradiated polyethylene.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 991-1002 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric measurements between -50 and 60°C have been made on isotropic and oriented samples of poly(chlorotrifluoroethylene) with draw ratios λ of 1 to 3.5 at frequencies ranging from 30 Hz to 1 MHz. For the oriented samples, the dielectric loss has been measured with the electric field normal (ε⊥″) and parallel (ε∥″) to the draw direction. At low frequency (say 60 Hz) the loss data for the oriented samples reveal two peaks at 25 and -5°C, which are associated with the amorphous (γa) and the crystalline (γc) relaxations, respectively. Analysis of these data using a two-phase model yields values for the amorphous orientation function fa which are only about 25 to 60% of those for the crystalline orientation function fc. Upon annealing, the anisotropy ε⊥″/ε∥″ at the γa peak decreases significantly while that at the γc peak remains largely unchanged. This implies a roughly unaltered fc and a large decrease in fa, which is consistent with the results of wide-angle x-ray diffraction and birefringence measurements.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1011-1013 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1047-1053 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Work on the surface-growth method of producing blend films from mixed solutions of two polymers has exposed a random fluctuation in both growth rate and composition of the blend film with time of deposition. The effects are explained by heterogeneous separation of the two polymer components in the solution induced by the stirring action of the rotor of the Couette apparatus used. The solution is thus converted to a colloidal sol which on cooling forms a gel which exhibits syneresis at room temperature. The sol-to-gel transition is thermally reversible.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1033-1046 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The variable-contrast method in small-angle neutron scattering has been applied to a study of the conformation of polystyrene-polyisoprene block copolymers in dilute solution. The experimental results reveal no intramolecular segregation effect in dilute solutions in toluene and cyclohexane.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1081-1105 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Films of chitosan, prepared by different fabrication processes, were examined at several structural levels, from the molecular to the macroscopic. This revealed the presence of polymorphic crystal forms, which varied with film treatment. Similarly, morphological structures varying from spherulites to rods were formed, depending on film processing conditions. The effect of structure on the mechanical properties, as well as the orientability of the films, were also investigated.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1141-1149 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An electron spin resonance (ESR) study has been made of radicals trapped in polyisobutylene irradiated at 77 K. It is concluded that only the —C(Me)2—CH— radical remains after heat treatment above 213 K. This radical shows a very sharp doublet ESR spectrum with hyperfine splitting of about 2.2 mT. A broad doublet ESR spectrum observed without warming, which was previously assigned as —C(Me)2—CH—is explained as a mixture of a doublet and a triplet due to the —C(Me)2—CH— and radicals. γ-irradiation at 77 K produces these major radical components and other carbon radicals as minor species. It has also been found that a conversion of other radicals into —C(Me)2—CH—occurs without decay on annealing below 183 K. Heating in the range 183-213 K causes both conversion and decay of the radicals. On annealing above 213 K, only decay occurs. The ESR spectra of polyisobutylene radicals are easily saturated by microwave power even at 1.6 μW. The mechanism of radiolysis for polyisobutylene is briefly discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1163-1166 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1173-1176 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1199-1209 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Partial molar heats of mixing ΔH1∞ and Flory-Huggins χ parameters have been determined for a series of polar and nonpolar organic probes in the polymer systems polychloroprene, poly(butadiene-acrylonitrile) (34 wt. % acrylonitrile), poly(ethylene-vinylacetate) (40 wt. % vinylacetate) and cis-1,4-polybutadiene in the range 65-85°C. Using the Flory-Huggins χ parameters, infinite-dilution solubility parameters δ2∞ were calculated for the polymers at 75°C to be 8.8 ± 0.2 for polychloroprene 10.0 ± 0.3 for poly(butadiene-acrylonitrile), 8.3 ± 0.2 for poly(ethylene-vinylacetate) and 7.9 ± 0.1 for polybutadiene. These δ2∞ values are in good agreement with literature δ2 values. δ2∞ values were also calculated using only polar or nonpolar probes. The change in δ2∞ as the set of probes changed was negligible, leading to the conclusion that Hanson's three-dimensional solubility parameter concept may not be applicable to the infinite-dilution case.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1231-1236 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mixtures of trifluoroacetic acid (TFA)-1,2-dichloroethane (1,2-DCE); TFA-dichloromethane (CH2Cl2); and TFA-trichloromethane (CHCl3) are excellent cellulose solvents at room temperature. TFA-1,2-DCE and TFA-CH2Cl2 are superior to pure TFA. Lyotropic cellulose mesophases were obtained in (20% w/v) solutions of cellulose in these solvent mixtures. The optical and optical rotatory powers of the solutions suggest that the lyotropic mesophase of cellulose is cholesteric. This implies that cellulose molecules are arranged in helical form in these solvent systems.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1269-1272 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1277-1279 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1280-1280 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1325-1331 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relation between the thermal behavior of extended-chain crystals (ECCs) of polyethylene and the phase transitions, i.e., orthorhombic ↔ hexagonal ↔ melt, of polyethylene at high pressures above about 400 MPa has been studied by high-pressure differential thermal analysis (DTA), and with a high-pressure and high-temperature x-ray diffraction apparatus equipped with a position-sensitive proportional counter measuring system. The original sample used in this study consists mainly of two kinds of ECC, which we designate as “ordinary extended-chain” crystals (OECCs) and “highly-extended-chain” crystals (HECCs). Experimental results at pressures below 300 MPa substantiate the results previously reported: i.e., the phase diagram indicating the relation between the melting temperatures and pressure for the OECCs and HECCs can be determined for pressures up to 500 MPa.In heating at pressures above about 500 MPa, the peak intensity of the (100) reflection of the hexagonal structure decreases in two stages with increasing temperature. The phenomenon corresponds to the thermal behavior determined by high-pressure DTA in which two small endothermic peaks can be observed at temperatures above that of the crystal transition evidenced by the strong peak. This phenomenon suggests melting in two stages of hexagonal structures with different thermal stabilities, and that the change at higher temperature may be due to fusion of the hexagonal phase annealed either below or above the transition temperature.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1365-1369 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: X-ray diffraction, thermally stimulated depolarization, and piezoelectric current measurements have been carried out on uniaxially stretched poly(vinylidene fluoride) film, corona poled both negatively and positively at room temperature and at 90°C. Corona poling at elevated temperature considerably enhances the piezoelectric constant and is a more efficient way of charging the film than conventional thermal poling. Advantages over the latter are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1377-1383 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An acrylonitrile-styrene copolymer having 51.4 wt % acrylonitrile content was fractionated using dimethylformamide and a toluene-n-propanol mixture as solvent and nonsolvent, respectively. From characterization of the fractions, it is shown that the copolymer was fractionated principally in accordance with composition. The weight distribution curve of the copolymer was expressed as a function of both molecular weight and chemical composition on a two-dimensional contour map. The same plotting technique was applied to a copolymer having nearly the azeotropic composition.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1405-1422 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mixtures of two “monodisperse” samples of polystyrene (M1 = 4.53 × 104, M2 = 10.3 × 104; Mw/Mn 〈 1.01) in cyclohexane were allowed to separate into two phases at different polymer concentrations and temperatures. The compositions in the two phases were measured by gel permeation chromatography, and used to determine isothermal binodals. From the binodal data the critical temperature and concentration were estimated as functions of the composition of the polymer mixture, and the separation factor σ for each polymer component was calculated. In contrast with typical results in the literature, σ was almost independent of molecular weight of the polymer. It is shown by deriving a general expression for σ that theoretical prediction of σ requires accurate knowledge about the Flory-Huggins interaction parameter as a function of the concentrations of individual polymer components.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1435-1447 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study has been made of the effects of annealing at high temperature (130°C) on the dynamic mechanical properties and melting behavior of a series of ultrahigh-modulus polyethylenes. Although annealing always resulted in a substantial decrease in modulus, there were marked differences between samples of moderate draw ratio, depending on whether they are annealed at constant length or unconstrained. On the other hand, the differences were small for high-draw-ratio samples, indicating their greater thermal stability. In all cases the -50°C plateau modulus correlated well with the degree of crystal continuity estimated from wide-angle x-ray diffraction measurements of crystal length combined with small-angle measurements of the long period. The corresponding changes in melting behavior were entirely consistent with the changes observed in the mechanical stiffness. Both types of measurement together with the x-ray results have been used to gain an understanding of the morphological changes occurring on annealing.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1475-1488 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(p-phenylene benzbisoxazole) and poly(p-phenylene benzbisthiazole) belong to the class of extended-chain, rigid-rod polymers possessing high modulus, high strength, and good thermal and oxidative resistance. Fibers and films of these polymers are processed from anisotropic solutions in strong acids such as methane sulfonic acid or polyphosphoric acid. The electronic absorption and vibrational spectra of the model compounds have been investigated in order to characterize the structures in the solid state and in nonprotonic solvents. The dramatic intensity differences in the spectra obtained have been interpreted by variations in the dihedral angle between the plane of the phenyl group and the plane of the central heterocyclic ring which affect the resonance configuration between the two rings.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1505-1512 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It was shown by Weiss and Silberberg in 1975 that polyacrylamide gels prepared by copolymerization of acrylamide and N,N′-methylene bis-acrylamide in water are heterogeneous. A two-phase model developed in 1979 satisfactorily accounted for the permeability of the gels. These gels had been prepared under standard conditions of initiator and activator concentrations and involved precooling of the reaction mixture to 0°C with completion of the reaction at room temperature, a thermal history not very suitable for kinetic analysis. A procedure was, therefore, devised where gels are prepared at room temperature throughout. Much better correlations are then obtained, and it can be shown that the initiation is controlled by the initiator (ammonium persulfate) concentration times the activator (N,N,N′,N′-tetramethylethylene diamine) concentration raised to the 1.5 power. These data, discussed in terms of the two-phase model, show that the initiator concentration directly determines the number of crosslinks in the more dilute, permeability-determining, gel phase. The faster the initiation, the less permeable a gel results. An increase of permeability with overall degree of crosslinking at constant monomer concentration is a feature only of gels prepared at sufficiently low polymerization initiation rates.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1549-1565 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The possibility of producing high-modulus nylon 6 fibers by incorporation of lithium chloride (LiCl) in the polymer prior to spinning and drawing has been examined. Samples containing 2% and 4% LiCl (w/w) together with an unsalted control were studied. Particular attention was given to optimizing the spinning process by varying the melt temperature and the draw-down. The spun fibers were subsequently drawn in a tensile testing machine at 135°C, preliminary studies having established that this was desirable for the production of high-modulus material. The influence of annealing after drawing was also examined. Drawn fiber moduli in the range 8-9 GPa were obtained, compared with ca. 5-6 GPa for unsalted material. Limited structural studies (birefringence and wide-angle x-ray diffraction) suggest that the enhancement of modulus is due to an increase in the stiffening effect of extended molecules in the noncrystalline regions. Dynamic mechanical measurements show that there is reduced chain mobility in the disordered regions of the polymer, suggesting strong polymer-ion interactions. The salt can be readily removed by washing the fibers in boiling water, with significant reduction in moduli. This militates against commercial application of the salted fibers.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1603-1617 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The stress-strain behavior of randomly crosslinked polydimethylsiloxane (PDMS) networks was studied. The small-strain data obtained agreed well with available data on radiation-crosslinked PDMS networks. It was found that both the suppression of junction fluctuation and trapped entanglements have to be considered in order to account for the discrepancy between experimental data and the phantom-network theory. With the addition of a constant trapped entanglement term, Flory's recent network model describes correctly the behavior of our networks under tonsion and compression. The values of the parameters used in fitting the data are within the range suggested by Flory for typical rubber networks. Edwards' “potential pipe” theory did not correlate our data over the entire range of strain variation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1655-1656 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1659-1661 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1687-1704 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The morphology of the ionomer resin from which Nafion perfluorinated membrane products are made was studied with wide-angle and small-angle x-ray diffraction. A reflection observed in the small-angle x-ray scan from hydrolyzed polymer is attributed to ionic clustering. The effects of equiv wt, cation form, temperature, water content, and tensile drawing on this reflection were studied and are discussed.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1739-1744 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mean-square dipole moments 〈μ2〉0 for the (atactic) poly(4-methyl-1,3-dioxolane) chain [CH2OCH(CH3)CH2O—] were determined from dielectric-constant measurements carried out on two fractions dissolved in benzene. Simple examination of the chain structure leads to the predictions that this polymer should have a significantly larger value of 〈μ2〉0 than poly(1,3-dioxolane) itself, but that 〈μ2〉0 should be nearly independent of stereochemical structure. The first expectation is confirmed by the experimental results obtained, and the second by calculated results based on rotational isomeric state theory.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1769-1790 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Replica and thin-section electron microscopy was performed on a linear polyethylene fraction (Mw = 1.89 × 105, Mn = 1.79 × 10 5) which was either isothermally crystallized or quenched at difference temperatures. The results are numerically analyzed in such a manner so as to give the distribution of the total long spacing and of the crystallite and amorphous thicknesses. The quantitative information about the maximum and minimum values for these parameters at each crystallization temperature yields important clues as to possible molecular processes involved. Qualitative information regarding general morphology, molecular tilt with respect to the lamellar surface, and possible crystallographic faults are also discussed.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1801-1801 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1817-1826 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two types of films showing different characteristic x-ray equatorial patterns were prepared from chloroform and N,N-dimethylformamide solutions of poly(γ-methyl L-glutamate-co-γ-benzyl L-glutamate). In the film cast from chloroform solution, the x-ray pattern on the equator consisted of a remarkable mixture of sharp and diffuse reflections, with the sharp reflections corresponding to integral values of 1/3k. On the other hand, in the film cast from N,N-dimethylformamide solution, a well-defined x-ray pattern was observed. An explanation for this characteristic pattern of chloroform-cast film was made on the basis of a structural model wherein stacking faults or dislocations are incorporated into the ordered structure characteristic of N,N-dimethylformamide-cast film. Two domains divided by a stacking fault are mutually displaced along the (100) crystal planes, but the shape and size of the unit cell is everywhere the same. The intensity distribution of x-ray diffraction was calculated as a function of the probability of a stacking fault occurring in a regular sequence of (100) planes. The best correspondence with observation was obtained with a stacking fault in every three layers, on the average.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1865-1871 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Although the crystalline phase of poly(4-methyl-1-pentene) (P4MP) is less dense than the amorphous phase, the density difference is very small at room temperature. This makes it difficult to study the fine structure of P4MP by small-angle x-ray scattering (SAXS). It has therefore not been clear whether a so-called superlattice, or long-spacing structure, is formed in P4MP as in other synthetic polymers. However, it is found that raising the temperature increases the density difference sufficiently to make SAXS study feasible, and the existence of the long-spacing structure of P4MP is indicated. Annealing studies reveal two characteristic temperatures of 170 and 200°C: above 170°C the long-spacing structure is formed with an abrupt increase of crystallinity, and at 200°C the structure is further developed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 19 (1981), S. 1911-1921 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Brillouin scattering is used to study the internal structure of oriented films of poly(ethylene terephthalate). Splitting in the longitudinal spectrum is observed as the film is stretched, indicating that the crystalline region is developed gradually from the amorphous region. The hypersonic velocity data obtained from these two regions are used to draw directional maps of sound velocity propagation in different directions of the film. The results are discussed and correlated with a recently proposed model. The orientational parameter in the amorphous phase is calculated from the hypersonic velocity data as a function of stretch ratio. The results are found to be in good agreement with published values obtained by a different technique.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1-13 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Light scattering patterns are calculated for imperfect three-dimensional spherulites with fluctuations in the twist angle. The fluctuations are described in terms of a parameter characterizing the distance correlation function. Cases are considered in which (i) the principal axis of the scattering element makes a constant angle with the radius but there is disorder in the twist angle about the axis, and (ii) there is combined twist disorder and orientation disorder of the scattering elements. Calculations suggest that the disorder in the twist angle may lead to a decrease in the higher-order variation of scattered intensity with scattering angle and deviation from the four-leaf-clover-type scattering characteristic of a perfect spherulite at lower scattering angles. On the other hand, disorder in orientation has little effect on the scattering pattern.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 49-63 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An experimental study of the tensile properties, tear strength, hysteresis, and swelling ratio of model composite elastomeric compounds consisting of polybutadiene filled with glass beads has been carried out as a function of the size of the beads. The diameter of the beads ranged from 25 to 1000 μm and the volume fractions examined were 0.16, 0.092, and 0.048. Mechanical properties of the filled elastomers were functions of the loading (separation distance), the particle size (surface area/volume), and the elastomer-filler systems studied.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 99-106 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Reasons have been advanced why in some cases concentrated-polymer-solution viscosity measurements are not a suitable method for determining the degree of association of groups attached to polymer chains. These are based on the finite lifetimes of associates compared with the finite lifetimes of the entanglements, which are the major contributors to concentrated-polymer-solution viscosities. The validity of these reasons has been checked in a system where the degree of association of polymer chains can be measured spectroscopically. It was found that the viscosity of these solutions was considerably less than that calculated by the concentrated-solution viscosity equation for solutions of polymers of the average molecular weight expected from the spectroscopically found degree of association.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 117-130 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(p-phenylene sulfide) (PPS) is a melt- and solution-processible polymer which on treatment with AsF5 forms a blue-black material with a conductivity of 1-10 Ω-1 cm-1. Thermopower measurements indicate that the resulting polymer is p type, consistent with partial oxidation of the PPS by the AsF5. The rate and extent of this doping process prove to be particularly sensitive to the degree of crystallinity of the starting polymer. There is also evidence of crosslinking of the polymer chains during the reaction with AsF5. The details of both the chemistry and physics of the doping of PPS and several of its derivatives are presented.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 131-139 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The temperature dependence of the reactivity ratio r2 (subscript 2 for styrene) is reported for 1-and 2-vinyl naphthalenes, 4-halogeno-1-vinyl naphthalenes, 2- and 3-vinyl phenanthrenes, and o-methylstyrene. The monomers are classified with respect to In (1/r2) and ΔH # and ΔS# (the differences in activation parameters for homopropagation and crosspropagation). It is shown that the reaction is entropically controlled. It appears that there is no correlation between stabilization energy (ΔE)rs and ΔH# and that the correlation with In(1/r2) is only apparent. The origin of this lack of correlation is analyzed and a new index of reactivity is proposed; its correlation with ΔH# is quite satisfying.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 191-203 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of polycaprolactone (PCL) with chlorinated polyethylenes (PECls) having chlorine contents of 25, 30, 36, 42, and 48% by weight were prepared and studied by differential scanning calorimetry and small-angle light scattering (SALS). It was found that blends made with PECls containing 30% or more chlorine are completely miscible with PCL (a single glass transition temperature Tg is found) while the PCL/PECl(25) blends are immiscible. PCL crystallizes in the miscible blends at any composition and it has an enthalpy of fusion which decreases only slightly with PECl content. Blends in the PECl composition interval of 0-80% are spherulitic, as shown by SALS, but a rodlike morphology is found at the 85% composition and dispersed crystals are observed at higher compositions. It is suggested that the k parameter of the Gordon-Taylor equation can be taken as a measure of the strength of the specific interaction between PCL and PECl. Low values of k (0.26 and 0.35) are found for PCL/PECl blends but a higher value of k (0.51) has been reported for PCL/poly(vinyl chloride) (PVC) blends, indicating a stronger interaction in the latter mixtures. In agreement with these findings poly(α-methyl-α-n-propyl-β-propiolactone) and poly(valerolactone) are not miscible with PECl, whereas they were previously shown to be miscible with PVC.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 225-233 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The authors describe small-angle neutron scattering measurements of the screening length ζ in polyacrylamide-water gels. Although these are inhomogeneous systems, the screening length is clearly observable and is in good numerical agreement with the relation E = 3kT/4πζ3, where E is the longitudinal elastic modulus of the gel obtained from measurements of the intensity of qu-asielastically scattered light. Static light scattering observations reveal a larger-scale (ca. 30 nm) superstructure in the gel.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 259-268 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of copolymerizing small amounts of an ionic moiety (0-7 mol %) into the backbone of a polycondensation polymer have been investigated by a combination of linear viscoelastic, steady-shear, and extensional testing. At a constant viscosity in dilute solution, both the zero-shear-rate viscosity and the maximum relaxation time in the melt increase monotonically with an increase in the ionic character. These effects are present after the data are normalized to remove the increase in the glass transition temperature Tg with increased ionic content. Large-strain, steady-shear flow experiments showed that the viscoelastic memory of the melt is affected by ionic content. An increase in ion content causes a decrease in the effect of strain on the memory function. This effect is not apparent in extensional flow experiments, which indicate that the ionic content does not affect the response if the tests are conducted at a constant temperature above Tg.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 297-305 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: For some fibers, such as the nylon monofilaments studied here, quantitative information may be obtained from scanning electron micrographs of fracture surfaces. On these surfaces the segment of the cross section that supports the load at the instant of rupture is seen distinctly, and its area can be measured. Normalizing breaking load by this area provides a breaking stress characteristic of the final supporting segment. “Ultimate” breaking stresses calculated in this way indicate (i) For notched filaments, the ultimate breaking stress is almost constant with notch depth and also with strain rate. (ii) For un-notched filaments, there is an increase of breaking load with strain rate, due in part to the extent of the slow cleavage that precedes failure; however, the ultimate breaking stress increases as rate of strain decreases. These two findings are incompatible with mechanisms of failure based on growth of microcracks by heat- and stress-activated chain breakage. A possible explanation involves rearrangement of microfibrils within the fiber which alters their strength distribution. (iii) The apparent strength reduction on wetting nylon filaments in water is due to a faster rate of growth of the slow-cleavage area; the ultimate breaking stress is unchanged, except at high rates of strain.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 327-344 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The existence of local order in two epoxy resins of the diglycidyl ether of bisphenol-A (DGEBA) type has been investigated using Rayleigh scattering and Brillouin spectroscopy. The resins differ in their molecular weight distributions and their relative concentrations of epoxide and hydroxyl groups. The complementary use of both techniques in elucidating the thermal behavior of local order is illustrated, and the use of the latter technique to study thermal acoustic phonons and hypersonic relaxation is discussed. Both techniques independently show that molecular aggregates exist in each resin system. The scattering-envelope dissymmetry shows that the resin with the high epoxide/hydroxyl group ratio contains aggregates up to 20 nm in size, and the low-ratio resin exhibits sizes up to 70 nm. These aggregates are thermally unstable in the temperature range studied (293-443 K). Dissolution in chloroform shows that these aggregates are reduced in size and that further structural changes occur which are dependent on solvent concentration. Aggregate volume fractions were determined for a range of aggregate size. Brillouin spectroscopy indicated that both resins exhibit hypersonic relaxation in the temperature range studied. The complex longitudinal moduli of the resins were superimposable under a WLF temperature transformation comparable to the difference in their static glass transition temperatures. Molecular aggregate size, number, and stability are related to the epoxide/hydroxyl ratio of the resins and the degree of intermolecular hydrogen bonding.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A single master logarithmic stress relaxation curve of reduced modulus as a function of reduced time is established for a styrene-butadiene rubber (SBR) system, accounting for the effects of crosslinking density, temperature, and time. The results from recent tests involving uniaxial and various biaxial strain states at finite strain levels may be represented by a unique strain-energy function W of the Valanis-Landel separable symmetric type, \documentclass{article}\pagestyle{empty}\begin{document}$ W = \sum\limits_{i = 1}^3 {w(\lambda_i)} $\end{document} where the λi are principal extension ratios. These two representations demonstrate that the mechanical response of whole families of elastomeric materials may be predicted once a single member of the family is fully characterized.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This article proposes a temperature-jump (T-jump) approach for characterizing the kinetics of volume recovery in glassy materials. The kinetic characterization is based on the Kovacs-Aklonis model. This incorporates a retardation-time spectrum which shifts according to both the temperature and the instantaneous volume. The proposed experiments involve measuring the change in recovery rate caused by an abrupt temperature jump. Although an analogous procedure has been used to determine the activation energy for linear viscoelastic creep, the analysis for volume recovery is complicated by its inherent nonlinearity. Nevertheless, accounting for the nonlinearity by a reduction of the time scale permits the T-jump results to be analyzed. In particular, the T-jump approach can be used to: (i) test a particular functional form for the shift factor and (ii) determine the previously unmeasurable parameter x, which defines the relative importance of the temperature dependence and the volume dependence in this function. In addition, numerical simulations indicate that the proposed method can be implemented in the laboratory.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 457-472 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thin films of a polyester of lactic and glycolic acid were prepared to give controlled amounts of disk spherulites. The spherulite contents ranged from zero to 100% and were accurately measured. The stress-strain properties of the films were then determined at 60°C, i.e., about 20°C above the glass transition temperature Tg. The mechanical behavior varied quite systematically with spherulite content and displayed little dependence on spherulite size. It was found that much of the mechanical data could be reasonably well described by a simple composite model. In addition, the yield strain as well as the strain to break could be principally coupled to the deformation of only the amorphous phase. SEM and optical microscopy studies supported the above conclusion, also demonstrating that the isolated spherulites adhered well to the amorphous matrix and behaved as stress concentrators in the system when the deformation temperature was above Tg.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Bimodal networks consisting of very short and relatively long poiydimethylsiloxane (PDMS) chains were studied from 30 to -52°C in an attempt to elucidate the anomalous increases in modulus [f*] exhibited by such elastomeric materials at high elongations. Temperature was found to have very little effect on (i) the elongation at which the upturn in [f*] becomes discernible, (ii) the elongation at which rupture occurs, and (iii) the total increase in [f*] up to the rupture point. The standard force-temperature (“thermoelastic”) plots were linear, but gave values of the energetic contribution to the total force which were significantly smaller than those universally obtained on unimodal, long-chain PDMS networks. Birefringence-temperature relations were also found to be linear, and yielded values of the optical-configuration parameter and its temperature coefficient which were in satisfactory agreement with the corresponding values reported for unimodal PDMS networks. These results indicate that even at very low temperatures the observed increases in modulus (and consequent improvements in ultimate strength) are due to non-Gaussian effects arising from limited chain extensibility, rather than from intermolecular reinforcing effects such as strain-induced crystallization.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 557-560 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 561-578 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Neutron scattering data for melt-crystallized polyethylene have been analyzed in order to clarify to what extent the chain folding is randomly reentrant. No attempt has been made to specify the molecular conformation in every detail, and the emphasis is on distinguishing between different classes of conformation. The most random folding corresponded to a model where the folding is imposed solely by the criterion of the chain segments moving the least possible distance during the crystallization process (a “freezing-in” model). This has been shown not to be compatible with published data. For this model analytic calculations are possible based on the projection of a three-dimensional Gaussian distribution onto a plane. A subunit model is then proposed which requires substantial local rearrangement of the chain as it folds during crystallization, but where the distribution of the subunits within the whole molecule is imposed by the preexisting Gaussian chain of the melt. Arguments based on space filling considerations are invoked, with the postulate of a surface structure which is neither crystalline nor truly amorphous. Anything approaching a random switchboard model (e.g., the freezing-in model which we consider) is contrary to both space filling considerations and to the comparison of observed and calculated neutron scattering. The analytical calculation which was performed for the freezing-in model was employed so as to simplify calculations for the subunit model. For scattering intensities over a wide range of scattering angle it is deduced that only the structure within the subunit need be considered. Numerical computer calculations involving only a small number of stems were then carried out for a number of different subunit structures, and some general features are noted which restrict the type of model which can explain the data. As in previously published analyses, a very high proportion of adjacent folds is not compatible with the results. A row model for the stems within a molecule can achieve good agreement, either with straight rows or with a certain amount of “stagger” incorporated. Up to about 40% of the folds could be adjacent. Models based on two-dimensional random walks did not give good agreement.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 623-632 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: When two shear deformations γ1 and γ2 are successively applied to an entangled polymeric system, a composite temporary network is formed. In this article a simple method is proposed for evaluating separately the contributions from the component networks of different deformations, γ1 + γ2 and γ2, to the observed shear and normal stresses. The method is applied to literature data for a polystyrene solution. It is revealed that the entangled chain segments formed between the applications of two deformations relax very rapidly, while those formed prior to the first deformation do not relax for quite a long time. The result is in accord with the conjecture based on the tube model of entanglement that the chain ends lose their orientation as the chain creeps out of an oriented tube.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 651-658 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A novel method for investigating the morphology of multiphase polymers is discussed. In this procedure, inherent differences in secondary and backscattered electron emission from the various components rather than topographical variations are used to produce image contrast. The combined use of various selective stains and energy-dispersive x-ray analysis to accentuate and positively identify individual phases is discussed. The effects of coating thickness and type and changes in accelerating voltage on image quality are also described.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 743-750 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The characteristic ratios of stereoirregular polybutadiene and polyisoprene have been evaluated by a combination of intrinsic viscosity and light-scattering measurements under θ conditions. The polydienes were synthesized by anionic polymerization and thus had near-monodisperse molecular weight distributions and were of uniform microstructure. The polybutadiene C∞ was found to be 5.1, which is in good agreement with the Abe-Flory predictions. However, the value of 5.1 for polyisoprene is somewhat higher than prediced by theory.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 773-775 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thin films of spin-probed and spin-labeled poly(methyl methacrylate) (PMMA) have been examined by electron spin resonance (ESR) at X-band frequency (9.2 GHz) and at various temperatures. Direct spectral evidence is presented to indicate that the composite ESR spectra observed in a certain temperature range originate from two states of distinctly different mobility, one with slow motions corresponding to a glassy state and the other with fast motions corresponding to a liquidlike state. The coexistence of these two states at temperatures considerably below the glass transition temperature can be explained as a result of the effect of free volume in a solid polymeric glass.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 783-791 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An expression for local composition which describes nonrandom interactions between unlike molecules in polymer solutions is proposed. This expression makes the nonrandom model compatible with the one-fluid hypothesis and satisfies the limits of randomness when experimental conditions evolve in such a way. Data on several binary systems are studied using this model which represents simultaneously activity and heat-of-mixing data.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 837-844 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Molecular aggregation of the aromatic polyimide poly(4,4′-oxydiphenylene-pyromellitimide) is influenced by the initial imidization temperature and by cold drawing. The effect of molecular aggregation in polyimides on their mechanical properties has been investigated. The density of a polyimide in which molecular aggregation gives an amorphous state is increased slightly by cold drawing. On the other hand, if molecular aggregation leads to a heterogeneous two-phase structure, the density is decreased by cold drawing. With increasing initial imidization temperature, the α absorption peak in dynamic tensile measurements becomes broader and smaller, and shifts to a higher temperature. From analysis of correlations between molecular aggregation and mechanical properties, it is concluded that the mode of molecular motion corresponding to the α dispersion in polyimide is a long-range cooperative motion of the main chain which is associated with the glass transition.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 893-898 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Exact expressions are derived for the spinodal, critical conditions, and separation factor of a ternary solution consisting of a pure solvent and two monodisperse homologous polymers in which the Flory-Huggins interaction parameter χ depends separately on the concentrations of the polymer components. The results allow one to see the difference from previous expressions obtained with χ depending on the total concentration of the polymer, and are expected to be useful for experimental determination of the Gibbs free energy of ternary solutions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 929-930 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 953-959 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reorientational relaxation of 9-cyananthracene fluorescent label molecules has been measured in bulk polybutadiene and solutions with cyclohexane by a fluorescent depolarization technique. The procedure adopted consists in the incorporation of an Arrhenius temperature dependence of the orientational relaxation time in the Perrin equation, thus obviating the necessity of an independent determination of the intrinsic polarization ratio P0 and enabling one to obtain the preexponential factors and the activation energies of the reorientational relaxation times. The most noteworthy result in our view is the validity of the Arrhenius equation for the effective microviscosity as opposed to the validity of the Fulcher-Vogel-Tamann equation with a glass point of T0 = 136 K for the shear viscosity of a polymer solution (90%).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 981-987 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A spectrophotometric method was developed for measuring the birefringence of highly oriented synthetic fibers. This method surmounts the low birefringence limit of the standard quartz compensator method and the difficulties in interpretation of the photographic fringe method. A highly oriented aramid fiber gave birefringence values of 0.60-0.75 by this method, compared with 0.25 for polyester and 0.06 for nylon by other conventional methods. The operating principles and excellent results of this new method provide a basis for the extension of routine birefringence characterization to highly oriented fibers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1013-1018 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The production of oriented “crystalline” fibers of an atactic polymer, poly{1-[6-(4-biphenylyloxy)hexyloxycarbonyl]ethylene} is reported. The x-ray diffraction is consistent with a two-chain unit cell with a = b = 23.5 Å, c = 6.48 Å, and γ = 120. Although the cell is essentially hexagonal, the absence of screw symmetry along the polymer chain reduces the crystal symmetry to P A packing model consistent with these data is proposed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1069-1080 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A systematic study of the sodium and calcium salts of an ethylene-methacrylic acid copolymer is reported. Fourier-transform infrared spectroscopy (in the midinfrared region) is applied to the characterization of structural changes as a function of temperature and time of annealing. In the spectra of calcium ionomers, bands associated with carboxylate dimers are identified and assignments of specific spectral features to multiplets and clusters are discussed. The spectroscopic changes observed in the spectra of sodium ionomers differ somewhat from their calcium counterparts in that a single infrared band attributed to isolated carboxylate groups is observed. Assignments of specific bands to multiplets and clusters can, however, be made in a manner consistent with the interpretation of the spectra of calcium ionomers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1107-1128 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The technique of nitric acid etching followed by gel permeation chromatography has been used to determine the crystal length distribution in ultrahigh-modulus polyethylenes. The crystal length distribution has been studied as a function of draw ratio, polymer molecular weight, processing conditions, and annealing. The results confirm that although there is a considerable broadening of the crystal length distribution on drawing, the majority of crystals have lengths less that 500 Å. There are detailed changes in the length distribution due to changes in draw temperature, molecular weight, and annealing which are not always reflected in corresponding changes in the long period determined from small-angle x-ray scattering. Possible reasons for these discrepancies are discussed.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1129-1141 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crazes have been grown from crack tips in thin films of the following five polymers: polytertbutylstyrene (PTBS), polystyrene (PS), poly(styrene-acrylonitrile) (PSAN), poly(phenylene oxide) (PPO), and poly(styrene-methyl methacrylate) (PSMMA). These polymers represent a wide range of le values, where le is the chain contour length between entanglements. Quantitative transmission electron microscopy has been used to analyze the extension ratio λcraze and displacement profiles for these crazes. From these measurements the craze surface stresses have been computed by using the method of distributed dislocations. This analysis also permits an accurate measure of the level of the applied stress σ∞. These measurements show that the stress necessary for crazing increases as le decreases and that the higher surface stresses present at crack tips generate crazes that have higher λs than isolated crazes in the same polymers. Surface drawing is shown to be the dominant mechanism for craze thickening in all five polymers.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1175-1192 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Shrinkage of unconstrained low-density polyethylene samples and the retractive stress of samples with ends fixed have been investigated as a function of the annealing time tA and temperature TA on material drawn at room temperature to draw ratios λ between 4 and 6. The shrinkage increases with tA and TA. The retractive stress on a sample annealed with ends fixed goes through a maximum as the sample is annealed and then drops to a limiting value which increases with TA as long as TA is at or below 80°C and rapidly decreases with higher TA. The drop from the maximum to the limiting retractive stress, slow at lower TA and rapid at higher TA, seems to be a consequence of rapid pulling of chain segments out of crystal block in which interfibrillar tie molecules are anchored. This process is facilitated by the high TA, which softens the crystal matrix. At constant end-to-end distance, the contour length of the tie molecules is irreversibly increased, and this causes a reduction in the contribution of the affected tie molecules to the overall retraction stress. Hence one finds a substantially higher retraction stress during first heating than during subsequent cooling and heating of the drawn sample.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1193-1205 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The birefringence of model structures of ultraoriented polyethylene has been calculated by using the point-dipole concept and the polarizability tensor of the methylene group derived recently by Pietralla. For well-oriented chains the birefringence is determined by the combination of a negative anisotropy of the polarizability tensor of the methylene group and a positive anisotropy of the Lorentz tensor, both with respect to the chain direction. As a consequence it decreases with increasing density. The results are in agreement with experimental values of Mead, Desper, and Porter. In the model the amorphous regions are regarded as a mixture of planar and helical segments arranged in nematiclike bundles which additionally may have a certain distribution of orientation. The birefringence is not much affected by defects which, on the other hand, strongly influence the ultimate mechanical properties.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1223-1232 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dynamic mechanical properties of a series of polyester resins made from a maleic/phthalic anhydride-based unsaturated polyester crosslinked with each of styrene, 4-methyl styrene, 4-ethyl styrene, 4-n-butyl styrene, 4-isopropyl styrene, tertiary butyl styrene, 4-chlorostyrene, and 3,4-dichlorostyrene were studied. The order of the α transition temperatures was as expected from that for the homopolymers, except in the case of the chlorostyrenes, for which dipolar interactions with the polyester chain may be important. The styrene bridges appeared to be involved in a steric interaction (and in the case of the chlorostyrenes, a dipolar interaction) with the β relaxing ester species. It is suggested that both the γ and γ′ relaxations involve similar interactions between the matrix and the relaxing moieties. For the 4-n-butyl styrene resin, an additional relaxation below -170°C was observed, and is ascribed to relaxation of the n-butyl group.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1233-1247 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This article demonstrates that the neglect of nonlinear effects in the conventional counterion condensation theory for the double layer about a charged cylinder can be significant, especially for phenomena involving intramolecular or intermolecular interactions in dilute solutions. For concentrated solutions the Manning theory derives from a linearized superposition approximation for the potential, in contrast to the cylindrical-cell model, which explicitly treats interactions within an ordered array of parallel cylinders. A new theory which treats interactions explicitly while permitting disorder in two dimensions is presented, and predictions for the osmotic pressure are compared with those from the Manning and cylindrical-cell models.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1269-1278 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ultrasonic measurements were made on a series of eight crosslinked polyepoxides over the temperature range from 0 to 60°C at a frequency of 2 MHz. From these measurements the bulk (K) and shear (G) moduli were calculated. These data were then analyzed in terms of molecular component properties. Proceeding by analogy with Rao's rule for liquids, the authors found that K is not an additive property but the function U = V(K/ρ)1/2γ is an additive property. Here V is molar volume, ρ is the density, and γ is the Gruneisen parameter (for interchain vibrations). A similar relation was found to hold for shear modulus. In particular, G is not an additive property but W = V(G/ρ)1/2g is an additive property, where g = (1/2α) (∂ InG/∂T)p - 1/2 is the shear analog of the Gruneisen parameter. Using U and W, calculations were made of K and G as functions of temperature for the eight epoxies. These results agree with the measured values within the experimental uncertainty of the measurements.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1279-1287 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A rheo-optical investigation has been carried out on a sample of high-density polyethylene (HDPE) in an attempt to examine the nature of the α-relaxation mechanism. Dynamic mechanical and bi-refringence behavior was measured over the frequency range of 0.008-4.3 Hz and temperature range -40 to 100°C. The dynamic mechanical and birefringence data were reduced to a reference temperature of 50°C by a combination of horizontal and vertical superposition. The significance of the vertical shift factor has been discussed extensively in previous papers and is not dealt with here. An Arrhenius plot was made of the log of the horizontal shift factor versus reciprocal temperature for the mechanical and optical data. The mechanical data exhibited three distinct regions, the slopes of which led to activation energies of 70, 90, and 150 kJ mol-1. The temperature at which these dispersions occurred suggested the observation of the β, α1, and α2 relaxation processes. The optical data contained two distinct regions from which activation energies of 55 and 95 kJ mol-1 were obtained. The high-temperature α2 process was not observed in the Arrhenius plot; however, a maximum in K′ and a change in sign of K″ probably reflects a contribution from the α2 relaxation mechanism.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetic interpretation of the damage produced by heavy ions (3684Kr and 1735Cl from 1 MeV/amu) and γ radiation in cellulose triacetate leads to an exponential dependence on the ion fluence. A comparison of the fading effect produced by heavy ions and γ rays shows that the heavy ions, unlike γ rays, cause irreversible damage. Finally, a nonlinear dependence on the flux of ions and γ rays is found in the kinetics of radiation damage. This result is contrary to the usual assumption that heavy-ion flux, like γ-ray flux, is additive, at least for the fluxes of 109-2 × 1010 ions/cm2s and dose rates of 103-104 Gy/h used in this work.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1327-1340 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Tracks of heavy charged particles have been observed in cellulose acetate by conventional electron microscopy (100 kV) and by high voltage microscopy (1, 2 MV). The tracks are formed of successive islets following each other at distances of 70-150 Å. With the evolution of the diameter of these zones is shown the existence of a highly perturbed cylindrical volume (diameter 400 Å for the case of krypton) corresponding to regions in which free radicals have been created. The different techniques used do not allow observation of the latent track because of the complications of energetic phenomena: the electron beam current density being limited, the contrast is small and hence the resolution is restricted.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1289-1311 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Our earlier results on ασ and heavy-ion-radiation damage in cellulose triacetate (CTA) are compared with those of previous authors on UV-and γ-radiation damage in the same material. Thus the common effects of these different methods of irradiation can be distinguished from those characteristic of the radiation employed. With heavy-ion radiation the production of stable radicals is accompanied by C - O cleavage. In the case of 3684Kr (1 MeV/amu) ions, the number of free radicals produced is investigated, without distinguishing the species, by using the scavenger technique in the solid phase, combined with UV spectroscopy. On the other hand, C - O cleavage is observed by IR spectroscopy, with its inherent selectivity. A statistical study shows that the experimental curves representative of the evolution of the optical transmittance ratio before and after irradiation L(N) versus the ion fluence N are of exponential type: $$ L(N) = \alpha e^{\beta N} $$ where β is a parameter related to the volume damaged by a single ion and, therefore, to the latent track size. The latter is approximated by a cylinder whose height is equal to the range of the ion. For 3684Kr8+ (1.1 MeV/amu) the track length is 21 μ. For each type, damages are localized within a radius of 250 Å for free-radical yields, 148 Å for cellulosic chain cleavages, 108 Å for deacetylation, and 100 Å for opening of pyrannosic rings. The track length is 14 μ for 1735Cl6+ (1 MeV/amu), while the radius of the cylinder in which free radicals are produced is only 80 Å.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...