摘要:

AbstractMeasured intrinsic viscosities ([η]) at several temperatures (T) within the interval 280–350 K have been found to increase withTfor solutions of poly(phenyl acrylate) (PPA) in ethyl lactate. A decrease of [η] withTwas observed for aqueous solutions of poly(ethylene oxide) (PEO) at several temperatures within the range 276–358 K. The results have been treated on the basis of eight excluded volume theories, among which the best consistency was afforded by those of Kurata‐Stockmayer‐Roig, Fixman, and Stockmayer (Padé). These yielded values of −3.4 × 10−3to −4.7 × 10−3deg−1and −0.9 × 10−3to −2.4 × 10−3deg−1for the temperatur coefficient of the unperturbed dimensions of PPA and PEO, respectively. The derived θ‐temperatures were 287 K as the upper critical solution temperature for PPA in ethyl lactate and 365–382 K as the lower critic

ISSN:0007-1641    

DOI:10.1002/pi.4980200102

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractRadical graft copolymers of ethyl 2‐cyanoacrylate on to poly(butadiene‐co‐acrylonitrile), were prepared and characterized by infrared spectroscopy. Simultaneous homopolymerization of ethyl 2‐cyanoacrylate also occurred. The polymerization of ethyl 2‐cyanoacrylate is significantly affected by the presence of the pre‐formed dissolved elastomer, the overall activation energies in the presence and absence of elastomer being 80.8 ± 0.4 kJ mol−1and 77.0 ± 0.4 kJ mol−1, respectively. In each case the reaction was first‐order with res

ISSN:0007-1641    

DOI:10.1002/pi.4980200103

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractPolycondensation ofm‐diethylaminophenol with formaldehyde has been studied under various reaction conditions. The resins formed are fusible and soluble in common organic solvents. All the resin samples have been characterized by spectral studies, measurement of solution viscosity, estimation of M̄nand by t.g.a. The curing of selected resin samples by hexamine has been studied both by measuring percentage of cured material as a function of time at different temperatures and by differential scanning calorimetry. The d.s.c. data have been analyzed by various methods to evaluate the gross kinetic parameters of the curing reactio

ISSN:0007-1641    

DOI:10.1002/pi.4980200104

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractFinely divided inorganic solids can be used for drop stabilisation in suspension polymerisation. In order to clarify the role of these solids, experiments have been carried out using a model system in which wax drops were dispersed in water in the presence of magnesium hydroxide. Drop sizes were reduced if the hydroxide was precipitatedin situbefore dispersion of the wax. As the loading of this precipitate increased, the average drop size passed through a minimum. The presence of a surfactant modified the effect of the hydroxide. Electrolyte, which is formed in the precipitation reaction, also influences the drop size. The separate effects of solid hydroxide, surfactant and electrolyte are not additive. There is some evidence for a nucleating effect which may not be desirable in suspension polymerisation.

ISSN:0007-1641    

DOI:10.1002/pi.4980200105

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractSilicon has the ability to form polymeric chains, commonly linear chains of dimethylsiloxane, although other organic groups can be substituted for methyl. In addition, the properties of the resultant silicone polymers can vary with composition and curing procedure. This leads to a wide range of materials known as the silicones. This group of polymers, which have excellent biocompatibility, have been utilised to develop and manufacture a wide range of biomedical products. These range from simple tubing to complex implants, for example those used to replace diseased finger joints. The versatility of these materials has led to silicone products being employed in almost every medical speciality.

ISSN:0007-1641    

DOI:10.1002/pi.4980200106

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractLong‐column meniscus‐depletion sedimentation equilibrium has been used to determine M̄n, M̄wand M̄zfor the Na+and (CH3)4N+salts of a high molecular weight poly(styrene sulphonate). Consideration has been given to ways of avoiding the need for dialysis when dealing with polyelectrolyte sol

ISSN:0007-1641    

DOI:10.1002/pi.4980200107

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe intrinsic viscosities of solutions of polyvinylpyrrolidone (PVP) in water‐sodium dodecyl sulphate have been measured, for four different molecular weights of PVP, and different concentrations of sodium dodecyl sulphate at temperatures between 20 and 35°C. The exponentaof the Mark‐Houwink‐Sakurada equation has been determined, and the values of the short range interaction parameterKθ,and expansion factor αηderived. Above a certain concentration the sodium dodecyl sulphate is adsorbed on the polymer by means of hydrophobic attractions, and the consequent repulsion between anionic heads provokes expansion of the macr

ISSN:0007-1641    

DOI:10.1002/pi.4980200108

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe kinetic parameters for the curing reactions of initially uncured and partly cured samples of the diglycidyl ether of bisphenol‐A (DGEBA) with phthalic anhydride and quaternary ammonium compounds of guar gum or quaternary ammonium compounds of hydroxyethyl guar gum as catalyst, with or withoutn‐butanol as diluent, were determined using the differential scanning calorimetry technique with a dynamic scan. To evaluate the kinetic parameters, four different computational methods were applied. The reaction was found to be first‐order, with activation energy in the range 65‐96 k

ISSN:0007-1641    

DOI:10.1002/pi.4980200109

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe curing reaction of the acrylated diglycidyl ether of bisphenol‐A (DGEBA) with benzoyl peroxide has been investigated by differential scanning calorimetry at three different heating rates. The overall cure kinetics were found to be first‐order, with Arrhenius parametersE=83 kJ mol−1and InA= 16.5 min−1, independent of the scan rate, up to at least 90% con

ISSN:0007-1641    

DOI:10.1002/pi.4980200110

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA range of polymers carrying amino‐functions [NHEt, NHBun, NEt2, NPr 2n, N(CH2CH2CH2NH2)2, NMeCH2CH2CH2NH2or NEtCH2CH2CH2NH2] has been synthesised via amination of styrene‐vinylbenzyl chloride copolymers, poly(epichlorohydrin) and poly(2‐chloroethyl vinyl ether), and via homopolymerisation and copolymerisation (with styrene) of (n‐butyl)(vinylbenzyl)‐ammonium chloride. Some of the polymers showed promise as curing agents for e

ISSN:0007-1641    

DOI:10.1002/pi.4980200111

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY