摘要:

Copolymers of 5-methylenebicyclo(2.2.1)-2-heptene and maleic anhydride were prepared by free radical copolymerization. Copolymers of constant composition with an alternating arrangement of comonomers but of varying solubilities, degrees of cross-linking, and molecular weights were obtained. The effects of comonomer feed ratios, comonomer concentration, initiator concentration, and temperature were studied. Copolymers of 5-methylenebicyclo(2.2.1)-2-heptene and maleimide, bicyclo(2.2.1)-2,5-heptadiene and maleic anhydride, and 1,2,3,4,4a,5,8,8a-octahydro-2-methylene-l,4,5,8dimethanonaphthalene and maleic anhydride were also investigated.

ISSN:0022-233X    

DOI:10.1080/00222337108061038

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Poly (β-ethynylnaphthalene), which has not been previously prepared and characterized in detail, was prepared with a Ziegler-Natta type catalyst. The polymer is reddish in color, soluble in aromatic solvents, and gives a positive color test for conjugation with antimony trichloride. The polymer has a molecular weight of up to 2091. Its IR and W spectroscopic characteristics are in accord with a modified conjugated polyene structure. It is thermally stable up to 470°, and probably partially crystalline.

ISSN:0022-233X    

DOI:10.1080/00222337108061039

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Thermal polymerization of diphenyldiacetylene in the absence of a catalyst is a second-order reaction. The rate of polymerization is proportional to the square of monomer concentration, and the resultant molecular weight of the polymer is independent of the monomer concentration. The results suggest a mechanism in which bimolecular initiation and bimolecular termination steps are involved. The IR, NMR, UV, EPR, and mass spectral properties of the polymer are described.

ISSN:0022-233X    

DOI:10.1080/00222337108061040

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

A study of the polymerization of methyl methacrylate (MMA) in benzene initiated by p-methoxy-p′-cyanodiphenyldiazomethane (MCD) was made. The initial rate of the polymerization, Rp, followed the equation: Rp= k[MCD]Oe0.56[MMA]0.95

ISSN:0022-233X    

DOI:10.1080/00222337108061041

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Methyl acrylate in dimethyl sulfoxide was polymerized by 2537 A ultraviolet light. The photo reaction exhibited zero-order kinetics for a given initial concentration and produced short chain polymers (M[Mbar]W∼ 20,000). Low sulfur values of isolated polymers indicated no appreciable solvent incorporation during the polymerization.

ISSN:0022-233X    

DOI:10.1080/00222337108061042

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

The change in relative reactivity in the cationic copolymerization of 2-chloroethyl vinyl ether and styrene derivatives was investigated with various catalysts and solvents. p-Methoxystyrene, p-methylstyrene, and a-methyl-styrene were used as styrene derivatives. The styrene content in the co-polymer increased when a polar solvent and/or a strong catalyst was used. The change of relative reactivity in the copolymerization of 2-chloroethyl vinyl ether with styrene derivatives was much greater than that in the copolymerization between vinyl ethers or styrene derivatives. When nitro-ethane was used as a solvent, not only the polarity but also the nucleophilicity influenced the copolymer composition. The results were discussed by two energies, Eπand Ers, which are measures of complex formation between monomer and carbonium ion, and stabilization energy in the transition state, respectively.

ISSN:0022-233X    

DOI:10.1080/00222337108061043

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

An integral dynamic reactor has been used for the continuous measurement of the instantaneous polymerization rate. With ethylene as monomer, the rate goes through a maximum after a few minutes, then levels off, and finally decreases owing to the blocking of the surface by the polymer. The catalytic activity may be calculated safely from the maximum instantaneous rate, after correction for the monomer consumption along the column of catalyst. As examples of application, it is shown that the catalytic activity goes through a maximum with either the chromium content at a fixed temperature of polymerization or with the temperature at a fixed chromium content.

ISSN:0022-233X    

DOI:10.1080/00222337108061044

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

2,2-Diphenyl-1-picrylhydrazyl (DPPH) is reversibly adsorbed at acidic centers on the surfaces of a variety of common mineral pigments and fillers, and undergoes a subsequent irreversible reaction with adsorbed water or surface hydroxy groups to yield 1,1-diphenyl-2-picrylhydrazine, 1-(4′-nitrophenyl)-1-phenyl-2-picrylhydrazine, and 4,4′-oxybis[N-(4-picryliminocyclohexa-2,5-dienylidene)aniline] as the major products. The rate of the irreversible reaction on kaolinite is second-order with respect to DPPH and probably depends on the disproportionation between a DPPH and a protonated DPPH molecule. The possible use of DPPH as a probe for the activity of mineral fillers in polymer chemistry, and some implications on its use as a diagnostic test for radical species are discussed.

ISSN:0022-233X    

DOI:10.1080/00222337108061045

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

The chemical activity of mineral fillers, under conditions similar to those encountered in filled-polymer systems, has been studied. It is shown that, contrary to previous views, the alumino-silicates have strongly acidic surfaces and that this surface acidity influences the chemical reactions in polymeric composites. Although the number of acid sites is significantly less than those of cracking catalysts, the strength of the sites is of a similar order of magnitude. A study of the infrared spectra of pyridine adsorbed on kaolin has shown that both Lewis and Brønsted acid sites are present. The ratio of Lewis to Brønsted acid sites varies with the free moisture content of the clay.

ISSN:0022-233X    

DOI:10.1080/00222337108061046

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor

摘要:

Different techniques and mechanisms of hydrolysis of isotactic, syndiotactic, and atactic PMMA are compared for over-all rates and reaction yields. A combined hydrolysis using a mixture of hydriodic and acetic acid gave the best results, and included the conservation of tacticity and size of the acid-ester copolymers obtained. These conclusions have been confirmed recently by several operators.

ISSN:0022-233X    

DOI:10.1080/00222337108061047

出版商:Taylor & Francis Group    

年代:1971

数据来源: Taylor