摘要:

AbstractCopolymers of poly(acrylamide‐co‐acryloyloxyethyltrimethylammonium chloride or AM–CMA) and poly(acrylamide‐co‐methacryloyloxyethyltrimethylammonium chloride or AM–CMA) prepared by inverse emulsion polymerization were characterized by different analytical techniques. The chemical composition of the copolymers was estimated by elemental analysis and by nuclear magnetic resonance spectroscopy (NMR). NMR spectroscopy and computer simulation were further used for investigating the polymers' sequence distribution. The poly(AM–CMA) copolymers are chemically more homogeneous than are the poly(AM–CMA). The configurational propagation of dyads and triads for the homopolymers obeys Bernouilli's statistics. For the copolymers, the chemical sequences distribution is governed by Markov's first

ISSN:0021-8995    

DOI:10.1002/app.1991.070421101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe copolymerization of epoxy‐terminated poly(ethylene glycol methyl ether) (CH3PEG–epoxide) with phthalic anhydride catalyzed by tertiary amines was performed ino‐dichlorobenzene at 100°C to prepare the PEG graft polyester. 4‐Dimethylaminopyridine was the most favorable catalyst to give the graft polyester with relatively high molecular weight. The acidity of the reaction solution decreased andMnof the graft polyesters increased with reaction time. The CH3PEG/phthalic acid ratio of the products was little affected by the kind of solvent and the reaction temperature above 100°C, butMnincreased with lowering the polarity of solvents and with raising the temperature. Other acid anhydrides, including maleic, succinic, tetrahydrophthalic, and pyromellitic anhydride, could be copolymerized with CH3PEG–epoxide. The number of branched CH3PEG chains was controlled by the mixing of low molecular weight epoxide such asn‐butyl glycidyl ether. CH3PEG component of the graft copolymers melted and crystallized at lower temperature than the raw CH3PEG because of the restriction on the trunk po

ISSN:0021-8995    

DOI:10.1002/app.1991.070421102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractStyrene butadiene rubber (SBR‐1502) was mixed with 100 phr superreinforcing furnace (SRF) black. The obtained rubber vulcanizate was subjected to electrical conductivity measurements at different values of tensile deformation. The logVvs. logIgraphs showed two distinct linear stages, the slope of which is nearly independent of the tensile deformation in the first stage and decreases with tensile deformation in the second stage. On the other hand, the tensile deformation was found to have an appreciable effect on the electrical conductivity. It decreases sharply as the sample is suddenly strained and then increases exponentially with time. An empirical formula describing this behavior is suggeste

ISSN:0021-8995    

DOI:10.1002/app.1991.070421103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractGraft copolymerization of vinyl compounds onto chitin was studied, and an efficient and reproducible procedure has been established, cerium (IV) being used as the initiator. The reactions with acrylamide and acrylic acid onto powdery chitin were carried out under various conditions to elucidate the polymerization behavior in terms of grafting percentage. The amount of cerium (IV) affected the polymerization most strikingly, and grafting percentages showed maxima with suitable amounts of initiator for both the monomers. As a solvent water proved to be superior to aqueous nitric acid except the reaction with a small amount of initiator. Under appropriate conditions, around 240 and 200% grafting percentages were achieved for acrylamide and acrylic acid, respectively. The resulting graft copolymers showed much improved affinity for solvents and hygroscopicity compared to the original chitin.

ISSN:0021-8995    

DOI:10.1002/app.1991.070421104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractSeveral diamine–p‐benzoquinone polymer/oligomers were synthesized to find those that exhibited superior properties, in addition to being able to displace water from wet, rusty steel surfaces. Unfortunately, many of these were found to be insoluble in most commonly used solvents and a few to be insoluble in all 34 solvents used in polymer solubility studies. The reason for this low solubility is believed to be the extremely regular structure of the polym

ISSN:0021-8995    

DOI:10.1002/app.1991.070421105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe solubilities of some polyamine–;quinone oligomers (PAQs) derived from various diamines were found to be incredibly low. Ethylene‐diamine–p‐benzoquinone products were insoluble in all 34 solvents used in assessing solubilities of polymers. Syntheses of copolymers/cooligomers of an amine yielding insoluble product with another that produces highly soluble amine were attempted. The increase in the solubilities of these copolymers/cooligomers as well as their appearances suggest that it is possible to produce PAQs from two different d

ISSN:0021-8995    

DOI:10.1002/app.1991.070421106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThis paper studies the effect of forced‐feed oscillations of an intentionally added chain transfer agent on isothermal free‐radical polymerizations carried out in continuous stirred‐tank reactors (CSTRs). A solution polymerization is first considered. The influence on the molecular weight distribution (MWD) of rectangular waves and impulsive trains of the transfer agent feed is theoretically and experimentally investigated. The main result is that (within certain limits) the average polydispersity can be increased at will with respect to its corresponding steady‐state (SS) value, without affecting the average number average chain length or the instantaneous monomer and initiator conversions. This result is extended to an emulsion copolymerization under sinusoidal oscillations of the transfer agent feed, where the “decoupling” between the average molecular polydispersity and other parameters (conversions, number average molecular weight, average number of branches per molecule, and the particle‐size distribution) is

ISSN:0021-8995    

DOI:10.1002/app.1991.070421107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractSingle‐ and two‐ply yarns of different counts were swollen slack under optimum conditions in aqueous zinc chloride and stretched back to original length. While two‐ply yarns showed an improvement in tenacity that was less pronounced in finer counts, single yarns always showed a fall in tenacity. Various properties of the treated yarns like packing fraction, fiber and yarn orientation, cross‐sectional morphology, etc. were evaluated to ascertain the likely factors responsible for the differential behavior of the chemically treated single‐ and two

ISSN:0021-8995    

DOI:10.1002/app.1991.070421108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractA thermotropic liquid crystalline polymer (LCP) based on wholly aromatic copolyesters based on hydroxynaphthoic and hydroxybenzoic acid was melt‐blended with a thermoplastic poly(phenylene oxide) by corotating twin screw extruder. Rheological properties, temperature transitions, dynamic and mechanical properties, and electron microscopy study have been performed. Rheological study indicated significant viscosity reductions with increasing LCP content leading to ease of processing. From the differential scanning calorimeter (DSC) and dynamic mechanical thermal analyzer results, these blends showed incompatibility for the whole range of concentrations. Mechanical properties were found to be slightly improved at low LCP and dramatically improved at above 50% LCP contents. In addition, impact strength was significantly increased up to two times after adding 10% LCP into the matrix. The morphology of blends was affected by composition. Droplets and stubby fibrils structures caused lower tensile strength, whereas fibrillar structure improved this propert

ISSN:0021-8995    

DOI:10.1002/app.1991.070421109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe preparation and properties of some new saturated and unsaturated esters of 2‐cyano‐2,4‐pentadienoic acid (CPDA) are described. A comparison is also made with the known CPDA monomers synthesized under identical conditions. It was found that the monomer yields are dependent on the structure of the corresponding CPDA esters. This fact was explained with solvatation effects, occurring during the isolation procedures. The base‐catalyzed anionic bulk polymerization of CPDA esters was studied by means of spectral methods. The data indicated that during the homopolymerization 1,4‐addition of monomer molecules takes place to give a steric copolymer consisting of 1,4‐cisand 1,4‐transstructural units. The ability of poly‐CPDA esters was also followed to form crosslinks at room and high

ISSN:0021-8995    

DOI:10.1002/app.1991.070421110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY