摘要:

The results of electrical conductivity measurements of α-chloroethyl ethyl ether and antimony pentachloride in methylene chloride solution presented previously have been reinterpreted according to the theory of Grattan and Plesch. The results are shown to be more self-consistent and useful than the earlier interpretation.

ISSN:0022-233X    

DOI:10.1080/00222338208056512

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The degree of polymerization was investigated in the homo-polymerization of ethyl and methyl acrylate in solution at 50°C. Molecular weights were determined by osmometry and viscometry. The mechanism of chain termination was found to be the combination of growing radicals in the polymerization of both monomers. The equation describing the degree of polymerization was derived considering the reactions of vibrationally excited radicals. Theoretical curves were found to be in good agreement with experimental data. Chain transfer constants were determined accordingly; in the EA/AIBN/DMF/50°C system CM= 9.0 × 1CT−5, Cs= 1.0 ×lo−5, Cs* = 8.3 × 10−5, and in the MA/AIBN/DMF/50°C system C. = 8.0 × 10−5, Cs= 3.4 ×10−5, Cs* = 12.5 × 10−5

ISSN:0022-233X    

DOI:10.1080/00222338208056513

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

In order to initiate a comprehensive study of graft copolymerization of vinyl monomers onto soluble protein-gelatin, we have studied grafting of ethyl acrylate (EA) and methyl methacrylate (MMA) onto gelatin using eerie ammonium nitrate (CAN) and eerie ammonium sulfate (CAS) as the redox initiator in an aqueous medium. A small amount of mineral acid (HNO3with CAN and H2SO4 with CAS) was found to catalyze the graft copolymerization. Graft copolymerization reactions were carried out at different temperatures. Maximum grafting occurred at 65°C both with EA and MMA. Percentage grafting has been determined as function of 1) concentration of monomer (EA and MMA), 2) concentration of initiator (CAN and CAS), 3) concentration of acid (HNO3 and H2SO4), 4) time, and 5) temperature.

ISSN:0022-233X    

DOI:10.1080/00222338208056514

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The thermal decomposition and the glass transition temperature (T) of polyisobutylene (PIB) were studied with a differential scanning calorimeter (DSC). The undecomposed and the decomposed polymers were analyzed by gel permeation chromatography for molecular weight distributions and by DSC for changes in the thermal properties, e.g., T. In the isothermal decomposition of PIB, weight loss, a, is independent of the molecular_weight (M) of the polymer. Random chain-scissions reduce [Mbar]wand [Mbar]nto average values of 10 × 103and 5.0 × 103respectively, and [Mbar]nto average value of 10 × 103and 5.0 × 103respectively, after isothemal treatments for 50 min intervals at temperatures ranging from 250 tp 375°C. The value of α is depolymerization controlled and the PIB is not quantitatively converted into monomer. Oligomers with a degree of polymerization of 12 are important products of the decomposition reactions. The activation energy of decomposition of PIB was found to be 184 kJ/mol, a value somewhat lower than that reported in the literature. Tgevalues (at q = 1 K/min) of undecomposed and decomposed PIB samples fall within ± 3.0° of 200 K in excellent agreement with reported values obtained by other means.

ISSN:0022-233X    

DOI:10.1080/00222338208056515

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The polymerization of N-vinylearbazole (NVC) by SK-500 molecular sieve obeys the relation, rate of polymerization (R) = [NVC]1,0(weight of SK-500)°−7Oat 30°C. Stirring increases the rate but the reaction order does not change. The highest catalytic activity, observed at 500°C precalculation temperature, does not correspond to the highest solid acidity of the sieve, realized at 200°C precalculation temperature. Pyridine and n-butylamine (⋍10−3M) inhibit and hydrogen chloride (⋍10−3M) and phosphoryl chloride (⋍10−4M) cocatalyze the polymerization. Both R and the degree of polymerization (F) increase up to a maximum at −9 −10% uptake of water (g/g of dry zeolite) and thereafter fall. Alumina and silica increase .Rp Pn decreases with an increasing alumina content and rises initially at low silica content, falling at a high concentration of the latter. Nitrobenzene retards the polymerization. P is independent of [NVC], percentage conversion, and weight of SK-500. It appears that the polymerization is initiated through Bronsted acid sites as well as through direct interaction of RE3+centers with a vinyl double bond of the monomer by a conventional cationic mechanism.

ISSN:0022-233X    

DOI:10.1080/00222338208056516

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0022-233X    

DOI:10.1080/00222338208056501

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor