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  • 1
    Electronic Resource
    Electronic Resource
    Melanin-concentrating hormone: A structural and conformational study based on synthesis, biological activity, high-field nmr, and molecular modeling techniques (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 609-622 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of Melanin-concentrating hormone (MCH) fragments have been synthesized and their biological activities compared with the parent peptide. The substructural units, 5-14 linear and 5-14 cyclic, have been used as models for MCH -  in 1H-nmr conformational studies. Conformational features predicted by molecular dynamics analyses find support in the nmr experiments.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360290314
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  • 2
    Electronic Resource
    Electronic Resource
    Chemical reactions and reactivity of primary, secondary, and tertiary diamines with acid functionalized polymers (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1589-1600 
    Details
    ISSN: 0887-624X
    Keywords: reactivity ; amines ; functional polymers ; anhydride ; carbonxylic acid ; crosslink ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactive melt processing of different types of diamines with polyethylene containing carboxylic acid groups and polystyrene containing anhydride groups was carried out. The reactivity of primary, secondary, and tertiary diamines with these acid polymers was determined using various techniques. Molecular weight increases due to crosslinking were observed through (1) changes in the torque during the reactive processing, (2) decrease in melt flow indices, and (3) decrease in solubility of the reaction products. The chemical compositions of the reaction products were examined by Fourier transform infrared (FTIR) spectroscopy. Thermal analysis using differential scanning calorimetry (DSC) was carried out to determine the crystallization behavior, glass transition temperatures, and thermal stabilities of the reaction products. Results show that the primary amine is the most reactive towards carboxylic acid or anhydride groups followed by the secondary and then the tertiary amine. Anhydride groups on polymers are of higher activity towards secondary or primary amino groups than carboxylic acid groups in the nucleophilic acyl substitution reactions. Reaction products crosslinked with the primary diamine are less stable than their parent acidic polymers. On the other hand, crosslinking with the secondary or tertiary diamine gives products with higher thermal stability than the parent acidic polymers. The formation of reversible and irreversible crosslinks with different types of diamines is also reported. © 1992 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300811
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  • 3
    Electronic Resource
    Electronic Resource
    A systematic nomenclature for cascade polymers (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 641-651 
    Details
    ISSN: 0887-624X
    Keywords: cascade polymers ; dendritic polymers ; arborols ; dendrimers ; starburst polymers ; nomenclature ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cascade (dendritic) polymers are discrete, highly branched, monodisperse polymers that possess branching patterns described by a mathematical progression. A systematic nomenclature that accurately represents these molecules is described. © 1993 John Wiley & Sons, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310307
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of reaction conditions on the grafting of 2-(dimethylamino)ethyl methacrylate onto hydrocarbon substrates (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1691-1702 
    Details
    ISSN: 0887-624X
    Keywords: grafting ; basic functionalization ; free radical polymerization ; methacrylate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The grafting of 2-(dimethylamino)ethyl methacrylate (DMAEMA) onto two model hydrocarbons, squalane and n-eicosane, and to linear low density polyethylene (LLDPE) has been investigated. The results of the study indicate that a high reaction temperature, 160°C, and a low concentration of monomer, less than 0.3 M, are optimum conditions for the grafting reaction. Reaction products, which consisted of grafted hydrocarbons and poly(DMAEMA), were separated by solvent extraction and vacuum distillation; samples were then analyzed by NMR and FTIR spectroscopy and size exclusion chromatography. 1H-NMR spectroscopy indicates that grafted squalane contained approximately 6 DMAEMA units per squalane residue. 1H- and 13C-NMR and molecular weight studies strongly suggest that the grafts onto the model hydrocarbons consist of single DMAEMA units. Results of the melt grafting of DMAEMA onto LLDPE show that the grafting efficiency and degree of grafting are substantially lower than were expected from the model system. © 1994 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080320911
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  • 5
    Electronic Resource
    Electronic Resource
    Grafting of 2-(dimethylamino)ethyl methacrylate on linear low density polyethylene in the melt (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 181 (1990), S. 1-22 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das Pfropfen von 2-(Dimethylamino)ethyl methacrylat (DMAEMA) auf lineares Polyethylen niedriger Dichte (LLDPE) in der Schmelze wurde mittels Messungen des Monomerumsatzes, des Pfropfgrades und der Pfropfeffizienz untersucht. Die Ergebnisse zeigen, daß das Pfropfen von DMAEMA auf LLDPE bereits bei niedrigen Temperaturen von etwa 90°C in der Schmelze durchgeführt werden kann, obwohl der Schmelzpunkt von LLDPE bei etwa 120°C liegt. Wenn die Pfropfreaktion bei zu hohen oder zu niedrigen Temperaturen durchgeführt wird, kann nur ein sehr niedriger Pfropfgrad beobachtet werden. Hohe Reaktionstemperaturen begünstigen die Polymervernetzung, was sich im Absinken des Schmelzindex bemerkbar macht. Die meisten Pfropfvorgänge werden während der Anfangsphase der Reaktion (unter den vorliegenden Bedingungen während der ersten 3 min) beobachtet. Eine Verlängerung der Reaktionsdauer über diesen Zeitraum hinaus führt zu verstärkter Vernetzung und erhöhter Produktion des Homopolymeren, was die Effizienz des Prozesses verringert. Organische Peroxide sind über einen weiten Halbwertszeitenbereich effektive Initiatoren der Pfropfreaktion, während Azoinitiatoren keine Pfropfung bewirken.
    Notes: Grafting of 2-(dimethylamino)ethyl methacrylate (DMAEMA) on linear low density polyethylene (LLDPE) in the melt has been studied through measurements of monomer conversion, the degree of grafting and the grafting efficiency. Results show that the grafting of DMAEMA on LLDPE can be carried out in the melt at temperatures as low as 90°C even though the melting point of the LLDPE is as high as 120°C. When the grafting reaction is carried out at too low or too high temperature, a low degree of grafting is observed. High reaction temperature favoured crosslinking of the polymer as indicated by decreasing melt flow index. Most of the grafts were obtained during the early period of the reaction (before 3 min under the reaction conditions used). Further increase in reaction time increased crosslinking and also produced more homopolymer, thus decreasing the grafting efficiency. Organic peroxides are effective initiators for the grafting reaction over a broad range of half-lives while azo initiators do not produce grafting.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1990.051810101
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  • 6
    Electronic Resource
    Electronic Resource
    Structure-property relationships in a reactively coupled ductile matrix/brittle dispersed phase blend (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1347-1362 
    Details
    ISSN: 0887-6266
    Keywords: polyethylene/polymethyl methacrylate blends ; reactive polymer blends ; ductile matrix/brittle dispersed phase blend ; instrumented impact testing ; toughening mechanism ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of t-butylaminoethyl methacrylate grafted polyethylene (PE-g-tBAEMA) with methyl methacrylate-methacrylic acid copolymer (PMMA-MAA) and polymethyl methacrylate (PMMA) were prepared in a Banbury type batch mixer. The effects of component proportions and processing conditions on the melt flow index, morphology, impact, and tensile properties of the resulting polymer blends were investigated. The interfacial chemical reaction was studied using Fourier transform infrared (FTIR) technique. It was observed that the melt index of the blends was reduced with increasing melt processing temperature and mixing time, indicating the formation of PE-g-PMMA block copolymer. New IR bands at 1554, 1628, 1800, and 1019 cm-1 were observed only for PE-g-tBAEMA/PMMA-MAA, the reactive blends, but not for PE-g-tBAEMA/PMMA, the nonreactive blend. These IR bands were attributed to the amide, carboxylate anion and methacrylimide formation resulting from the chemical reaction between the secondary amine on the PE-g-tBAEMA/PMMA moiety and the carboxylic acid on PMMA-MAA segment. The morphology of the blends in various compositions was examined using scanning electron microscopy (SEM) and related to their mechanical properties. All of the blends have a domain structure whose morphology is strongly dependent on the concentration of the dispersed phase. Furthermore, the PE-g-tBAEMA/PMMA-MAA reactive blends were shown to have much finer morphology than the corresponding nonreactive blends. For the reactive polymer blends consisting of brittle particles dispersed in the ductile matrices, the PE-g-tBAEMA/PMMA-MAA, impact and tensile result higher than predicted by the additivity rule were observed. The toughening of polyethylene by PMMA was explained by a “cold-drawing” mechanism. The Young's modulus of the blends and the extent of interfacial adhesion were analyzed with Takayanagi and Sato-Furukawa's theories. © 1993 John Wiley & Sons, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090311010
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  • 7
    Electronic Resource
    Electronic Resource
    Basic functionalization of molten linear low-density polyethylene with 2-(dimethylamino)ethyl methacrylate in an intermeshing corotating twin-screw extruder (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 1299-1313 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Functionalization of molten linear low-density polyethylene (LLDPE) with 2-(dimethylamino)ethyl methacrylate (DMAEMA) was studied in an intermeshing co-rotating twin-screw extruder using a peroxide initiator. The influence of monomer concentration, initiator concentration, reaction temperature, the screw speed, and the mean reaction residence time on the grafting reaction was investigated in order to determine the reaction conditions necessary to obtain a controlled degree of grafting, DG, while minimizing homopolymerization and crosslinking. Relatively high grafting levels can be obtained without excessive polyethylene crosslinking by using high monomer concentrations, wm, with low initiator concentrations, wI. DG increased with increasing monomer concentration when wm exceeded a certain value. Processing temperatures between 130 and 160°C are optimal to achieve high grafting efficiency, GE. Too high a processing temperature resulted in both low DG and GE. An optimal reaction residence time of about 5 min was found for wm = 23 wt % and wI = 0.56 wt % to obtain relatively high DG and GE. The melt flow index of the reaction product, MFI, increased with increasing wm at constant wI. This suggests that the DMAEMA monomer has the ability to suppress crosslinking of the LLDPE chains. The ability of the DMAEMA monomer to compete for initiator and polymer radicals and reduce LLDPE crosslinking was further demonstrated by the study of sequential addition of monomer and initiator along the extruder. The competition among the three reactions (i.e., the desired grafting, homopolymerization, and crosslinking) is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410537
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  • 8
    Electronic Resource
    Electronic Resource
    Equilibrium swelling properties of weakly lonizable 2-hydroxyethyl methacrylate (HEMA)-based hydrogels (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 783-788 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Hydrogles, sensitive to pH, were prepared by copolymerizing 2-hydroxyethyl methacrylate (HEMA) with 2-dimethylaminoethyl methacrylate (DMA). The mole fraction of the DMA monomer present during synthesis was fixed at 0.3, while the volume fraction of total monomer varied from 0.29 (I) to 1.0 (II). Swelling equilibria were measured in citrate of phosphate buffer for pH from 3.0 to 7.6 Swelling of the hydrogels depends on the volume fraction monomer present during synthesis, solution, pH, and identity of the buffer, Hydrogel I reached a four-fold larger swelling ratio (g swollen hydrogel/g dry hydrogel) in pH 3.0 citrate buffer, as compared to hydrogel II. Experimental results are interpreted on the basis of ideal Donnan equilibria. © 1994 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070520609
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  • 9
    Electronic Resource
    Electronic Resource
    In situ reactive compatibilization in polymer blends: Effects of functional group concentrations (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 655-678 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polystyrene (PS) and polyethylene (PE), along with their reactive counterparts, i.e., polystyrene having oxazoline reactive groups (OPS) and polyethylene with carboxylic acid groups (CPE), were melt blended in a Rheomix mixer. These blends were prepared by mixing these polymers in various proportions under a variety of conditions. In an alternate procedure the OPS, CPE graft polymer (OPS-g-CPE) was prepared by melt blending these two polymers beforehand, and subsequently this grafted polymer was used as a compatibilizer for PS-PE blends. The effects of the addition of OPS and CPE, on the one hand, and OPS-g-CPE, on the other hand, on the compatibility of PS-PE blends were investigated. The morphology of these blends was examined with a scanning electron microscope (SEM) and related to their tensile properties. The PS-PE blends are found to have the typical coarse morphology of incompatible blends and poor tensile properties while their reactive counterparts, OPS-CPE blends, have fine grain microstructure and show improved tensile strength throughout the range and improved elongation in the PE-rich blends. Relatively low concentrations of the reactive pair, oxazoline and carboxylic acid, are shown to be necessary to produce improved compatibility. The preblended graft copolymer OPS-g-CPE imparts compatibility to PS-PE blends also but not as effectively. This suggests that the addition of OPS and CPE during melt mixing of PS and PE forms OPS-g-CPE polymer at the interface and that these ingredients act as “in situ reactive compatibilizers” which improve physical properties.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070390316
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  • 10
    Electronic Resource
    Electronic Resource
    In situ compatibilization of polystyrene/polyethylene blends using amino-methacrylate-grafted polyethylene (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 2167-2177 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blends of a styrene-maleic anhydride copolymer (SMA) with polyethlene (PE) or polyethylene melt grafted with tertiary (PE-g-DMAEMA) or secondary (PE-g-tBAEMA) amino methacrylate were prepared by blending in a batch melt mixer. The morphology of these blends at various compositions was examined with a scanning electron microscope (SEM) and related to their tensile and impact properties. The SMA/PE blends are found to have the typical coarse morphology of incompatible blends and poor mechanical properties, while their reactive conterparts, SMA/PE-g-DMAEMA or SMA/PE-g-tBAEMA blends, show finer morphology and modestly improved tensile and impact strength. This was attributed to chemical interaction of the acidic anhydride and the basic amino groups. The greater improvement in morphology for SMA/PE-g-tBAEMA than for SMA/PE-g-DMAEMA suggests a stronger interaction between the secondary amino groups and the anhydride groups, possibly with the formation of SMA-g-tBAEMA-g-PE graft polymer through amide covalent bonds. The amide formation appears to occur at the interfacial region in the blends and is too little to be detected by Fourier transform infrared (FTIR) spectra. However, differential scanning calorimeters (DSC) and the viscosity measurements indicate crystallinity and molecular weight changes for the SMA/PE-g-tBAEMA blends, supporting an argument for the formation of SMA-g-tBAEMA-g-PE grafts at the phase interface.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070441213
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