摘要:

Polyesterimide offers a class of resin which combines the advantage of high temperature stability with ease of process-ability. Gum rosin, the exudate of pine trees, has been developed as the raw material for preparation of polyesterimide. Abietic acid of rosin reacts readily with maleic anhydride to form the Diels-Alder adduct, which reacts with p-amino benzoic acid to produce a dicarboxylic acid containing an internal imide group. The dicarboxylic acid reacts with diethylene glycol under melt polycondensation at higher temperature (260–300°C)to produce polyesterimide. The polymer is found to be soluble in highly polar solvents. The polymer is amorphous and of low molecular weight. Thermal stability of the polymer has been characterized, and the polymer was found to be thermostable.

ISSN:0022-233X    

DOI:10.1080/00222338208074392

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Lignin is a potential raw material for several applications. The immediate future should result in the development of lignin modifications yielding new polymers with special properties such as flame and/or thermal resistance. In this report a new reaction of lignins with chlorophosphazenes is discussed. The effect of different types of lignin and chlorophosphazene oligomers on the properties of the reaction product was investigated. The reactions were found to result in products with flame as well as with a base and acid hydrolitic resistance.

ISSN:0022-233X    

DOI:10.1080/00222338208074393

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The polymerization of methyl methacrylate (MMA) and acrylonitrile (AN) initiated by the oxygen-ascorbic acid (AA)-vanadyl ion (VO2+) system was studied at 40°C in dilute sulfuric acid medium. The rate of polymerization, Rp, was followed gravimetrically and found to be proportional to [MMA]1.3, [O2]0.6, and [VO2+]° at [VO2+] = 4–8 × 10−4Min the polymerization of MMA. In the polymerization of AN, R was dependent on [AN]1.5, [O2]0.5, and [VO2+]° at[VO2+] = 4–10 × 10−4M, while at [VO2+] > 10−3Mit was proportional to [AN]1.7, [O2]0.7, and [VO2+]0.6. A slight dependence of Rpon [AA] and [H2SO4] was observed in both polymerizations. An increase of ionic strength had an accelerating effect on Rp. An initial increase in Rpand then a decrease with temperature was noticed. A plausible reaction mechanism with initiation by the primary radical R produced from the dissociation of the O2-AA-VO2+complex and termination by mutual interaction with predominant oxidation of R by VO2+was found to be consistent for the observed kinetic results at all [VO2+] for MMA and for AN at low [VO2+]. Linear termination was found to be operative at high [VO2+] in the polymerization of AN. The chain length of the polymers was determined viscometrically.

ISSN:0022-233X    

DOI:10.1080/00222338208074394

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The application of the H2O2-cysteine redox system to induce graft copolymerization of methyl methacrylate onto cellulose was investigated under various conditions. The rate of grafting was determined by varying the concentrations of monomer, initiator, cysteine, acid, and temperature. The effect of some solvents was studied and a suitable reaction mechanism has been proposed.

ISSN:0022-233X    

DOI:10.1080/00222338208074395

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Poly(dimethylbutadiene) popcorn polymer oxidizes readily in the presence of oxygen at room temperature. Quantitative data are presented for the production of the major volatile product, 2,5-hexanedione, as well as for the secondary products: water, acetic acid, and acetaldehyde. Three reaction mechanisms formerly proposed for polyisoprene oxidation are considered for their applicability to poly(dimethylbutadiene) popcorn oxidation. Of these, one that assumes the formation of a Bevilacquatype peroxyalkoxy radical followed by hydrogen abstraction to form an alcohol group, double bond migration, formation of a peroxide radical adjacent to the alcohol, then elimination of a hydroxy radical and scission, can explain the experimental data.

ISSN:0022-233X    

DOI:10.1080/00222338208074396

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The hypochromism of styrene-methyl methacrylate random copolymers at 269.5 nm is attributed to strong interactions between the carbonyl groups of the ester and the phenyl rings. Support to this correlation is provided by model studies. Namely, the effect of several esters and other carbonylic solvents on the extinction coefficients of ethylbenzene and atactic polystyrene confirms the nature of the hypochromism. In order to eliminate the hypochromism of S-MMA copolymers, ester-type solvents are proposed. Indeed, when such solvents are used, a linear correlation between optical density at 269.5 nm and polystyrene content in the copolymers is found. Implications in gel permeation chromatography analysis are discussed.

ISSN:0022-233X    

DOI:10.1080/00222338208074397

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The distribution of volatile products from γ-irradiation of copolymers of styrene and methyl acrylate is independent of the composition of the copolymer and the same as that obtained from poly(methyl acrylate). The yields are less than proportional to the methyl acrylate content, Indicating a protective effect from the styrene units as observed previously in copolymers of styrene with methyl methacrylate. The flexural strengths of the copolymers, measured at 1°C, decrease with radiation dose for high styrene content, but increase for high methyl acrylate content. Samples irradiated in air have appreciably lower strengths than those irradiated in vacuum. Gel measurements show intermediate behavior for the copolymers between the homopolymers.

ISSN:0022-233X    

DOI:10.1080/00222338208074398

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Photografting of poly(methyl methacrylate), PMMA chains on natural rubber (NR) chain backbones was studied in benzene solution using quinoline-bromine (Q-Br2) charge transfer complex as photoinitiator and MMA as monomer at 35°C in visible light. Analysis of overall products for determination of grafting efficiencies was done following a method of selective extraction of only the free rubber fraction by benzene-petroleum ether mixtures followed by separation of the NR-PMMA graft copolymer from free PMMA in the residue (taken in benzene solution) by fractional precipitation with methanol. High grafting efficiencies in the range of 75–95% were easily and generally obtained. Effects of variation of concentrations of initiator, rubber, and monomer on grafting efficiencies were examined and reported. Prior photodegradation of the rubber resulted in substantial lowering in grafting efficiencies. Overall mechanism of graft copolymerization has been discussed.

ISSN:0022-233X    

DOI:10.1080/00222338208074399

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/00222338208074400

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

This review emphasizes the breadth of metallic and metallic-like polymers evaluated as to thermal properties. Techniques usefully applied to particular systems are noted with the aim of suggesting their application to other systems.

ISSN:0022-233X    

DOI:10.1080/00222338208074401

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor