摘要:

A phenolic copolymer has been grafted with oligomers of different chain lengths. Polymer-polymer complexation has been studied between graft copolymers and nonionic polymers, such as polyvinyl pyrrolidone) and poly(ethylene oxide), in an acetone-methanol mixture by several methods, e.g., viscosity, conductance, and apparent pH measurements. A distinct stepwise complexation between PVP and graft copolymers has been observed. The length of the side chain also seemed to influence interpolymer complex formation. Some of these observations have been interpreted with reference to the actual structure of the graft copolymers.

ISSN:0022-233X    

DOI:10.1080/00222338408056541

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Two new lightweight polymerized composites derived from perlite or fly ash were investigated. The properties of these materials were found to be superior to those of conventional concrete. These materials may find use in sculptural and architectural work where superfine and noncracking properties are required.

ISSN:0022-233X    

DOI:10.1080/00222338408056542

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Several new lightweight polymer concretes derived from industrial, agricultural, and naturally occurring waste materials were investigated. Various physicomechanical properties of these materials were studied. Such inexpensive and lightweight polymer composites, which have properties superior to ordinary reinforced cement concrete, may find wide applications in building technology and related areas and may serve as better substitutes for cement. Furthermore, recycling of such wastes from various sources may help to solve the present environmental pollution problems.

ISSN:0022-233X    

DOI:10.1080/00222338408056543

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

As a model for several polymer-related reactions, we have reexamined the reaction kinetics of benzoic acid with ethylene carbonate in which various quaternary ammonium salts were used as catalysts. The salt anion appeared to have little or no effect on the rate of reaction. At a 1:1 mole ratio of acid to carbonate, the reaction was zero-order to about 95% reaction. With tetraethyl-ammonium hydroxide catalyst at 0.4 mol% (based on carbonate moles), the activation energy was 20.8 kcal/mol with a preexponential factor of In A = 17.1 (activation entropy of -26 cal/deg). The activation energy for decomposition of the carbonate alone was 33.0 kcal/mol with a preexponential factor of In A = 27.3. This rules out previously suggested mechanisms that essentially involved decomposition of the carbonate prior to esterification. The proposed mechanism for the reaction involves the attack of the quaternary salt carboxylate on the methylene carbon of the carbonate. The attack causes ring opening and is followed by proton transfer and carbon dioxide loss from the carbonate half-ester intermediate. Ether linkages (such as diethylene glycol) are postulated to arise from the resultant alkoxide intermediate prior to protonation to give the hydroxyethyl ester rather than by separate postreaction of carbonate with the hydroxyethyl ester.

ISSN:0022-233X    

DOI:10.1080/00222338408056544

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

1-Butadienyl sulfides, mainly cis in configuration, are obtained by the base-catalyzed addition of mercaptans to vinylacetylene. bis-1-Butadienyl sulfides are readily polymerizable using azo catalysts, but mono-1-butadienyl sulfides are not, nor do they copolymerize with styrene or butadiene. They have a high Q-value and copolymerize well with other high Q monomers such as chlorostyrene and chloroprene. bis-1-Butadienyl sulfides were made by reacting a dithiol, such as bis-4-mercaptophenyl ether, with vinylacetylene or by a two-step process using mercaptoethanol followed by treatment of 2-hydroxyethylthiobutadiene with diisocyanate. The polymers were largely of 1,4-trans polydiene structure.

ISSN:0022-233X    

DOI:10.1080/00222338408056545

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Fractionation data of two poly(methyl methacrylate) samples prepared by suspension polymerization up to limiting conversion, in the presence of different amounts of 1-n-dodecanethiol, indicate that both samples have similar polydispersity factors, although the molecular weight distribution curve for the sample obtained with the highest chain transfer agent concentration is shifted to lower molecular weight values. The results obtained are qualitatively correlated with the high conversion polymerization theory proposed by Cardenas and O'Driscoll.

ISSN:0022-233X    

DOI:10.1080/00222338408056546

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Grafting of gelatin with acrylonitrile in zinc chloride medium has been studied using potassium persulfate as the initiator. The rate of grafting, grafting efficiency, and percentage of grafting are calculated. The grafting results are discussed in the light of the rate of grafting. The enhanced activity of the monomer is due to the formation of AN … ZnCl2 complexes.

ISSN:0022-233X    

DOI:10.1080/00222338408056547

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Acrylonitrile was grafted onto coir in aqueous solution using tetravalent cerium as initiator. The physical properties of grafted fiber (9.07 to -31.6% graft) were studied using standard methods and compared with those of the ungrafted one. Some of the useful physical properties of the fiber, such as density, resilience, and electrical resistance, were found to increase with an increase in the percentage of grafting, whereas some other properties, such as moisture content, moisture regain, charring temperature, thermal insulating capacity, electrical conductivity, and tensile properties, decreased under similar conditions. Possible explanations for such changes have been advanced, and suitable end uses of the modified fiber identified.

ISSN:0022-233X    

DOI:10.1080/00222338408056548

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The occurrence of head-to-head (HH) addition in the radical polymerization of diallyl oxalate (DAO) was examined under various polymerization conditions. The content of HH linkage in poly (DAO) was reduced in comparison with allyl acetate and diallyl succinate; this may be ascribed to the high polarity of DAO inducing a polar effect on the intermolecular propagation of the growing polymer radical, resulting in reduced HH addition. The correlation between addition modes and evolution of carbon dioxide characteristic of DAO polymerization at elevated temperatures is mechanistically discussed in detail, with special focus on the solvent effect and the reduced dismutation of the cyclized radical compared to the uncyclized one.

ISSN:0022-233X    

DOI:10.1080/00222338408056549

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The kinetics of the polymerization of acrylonitrile initiated by the redox system peroxydisulfate-cyclohexanol catalyzed by silver ion has been studied. The rate of polymerization was found to be directly proportional to the first power of monomer concentration and the square roots of peroxydisulfate, cyclohexanol, and silver ion concentrations. The effect of temperature has been investigated in the range of 35 to 60°C and the overall activation energy was found to be 4.6 kcal/mol from the Arrhenius plot. A plausible kinetic scheme has been proposed to account for the observations.

ISSN:0022-233X    

DOI:10.1080/00222338408056550

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor