摘要:

A number of monomers have been polymerized in the presence of catalytic and higher concentrations of SO2. The addition oft-butyl hydroperoxide greatly accelerates the rate of polymerization. The use of35SO2indicates that at catalytic concentrations of SO2(10−2mole/liter), only one or two molecules of SO2are incorporated in the chain, but, at high SO2concentrations, copolymerization of SO2with vinyl monomers occurs.

ISSN:0022-233X    

DOI:10.1080/10601326708053780

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

Studies on energy effect in the field of radiation-induced polymerization are quite rare as far as the author knows (1). In previous investigations (2) it was pointed out by us that the energy of radiation is also very important for radiation-induced polymerizations, particularly in solid-state polymerizations.

ISSN:0022-233X    

DOI:10.1080/10601326708053781

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

Polymers were obtained by free-radical solution polymerization of styrene, carried out by continuous feed-type polymerization. Molecular weights were determined by gel-permeation chromatography, light scattering, and osmotic pressure and viscosity measurements. A study of molecular structures indicated that polymerizations of styrene conducted in solution at relatively low temperatures and to a low degree of conversion can result in varying degrees of branching when certain initiating radicals are present.

ISSN:0022-233X    

DOI:10.1080/10601326708053782

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

The thermal polymerization of 1,3-cyclohexadiene to produce dimer and low molecular weight polymer is reported. The reaction initiated thermally and/or by benzoyl peroxide is kinetically of the second order, and the activation energy is 13.1 kcal/mole. The activation energy for the reaction is in quantitative agreement with that of the homopolymerization of 1,3-cyclohexadiene estimated from the kinetic study on the copolymerization with acrylonitrile. Evidently the dimerization process to give dimer as a product of typical Diels-Alder condensation is a competing type of reaction with radical polymerization to give a low molecular weight polymer. The ratio of the rate constant for two competing types of reaction at 200°C is found to be 1.21. The thermal polymerization in the presence of oxygen produces dimer in greater yield as a result of inhibition of the radical polymerization process.

ISSN:0022-233X    

DOI:10.1080/10601326708053783

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

When nickel peroxide was used as an initiator of the polymerization of methyl methacrylate, it was found that the radical polymerization proceeded easier than styrene under similar conditions, and that the polymers obtained at low temperatures showed somewhat increased syndiotactic sequence as compared with ordinary radical polymers. From the NMR determinations of the polymers resulted by nickel peroxide at various temperatures, the Bovey-Tiers relationship, that is, that the probabilities of formation of isotactic, syndiotactic, and heterotactic triads of monomer unit among the polymer chain are controlled by a single parameter of the probability of isotactic addition of monomer in the propagation step was confirmed in this case. Similarly, the ratioki/ksin rate constants for isotactic and syndiotactic additions in the polymerization by nickel peroxide in bulk was expressed by the following equation:

ISSN:0022-233X    

DOI:10.1080/10601326708053784

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

The polymerization of vinyl monomers such as styrene, methyl methacrylate, acrylonitrile, vinyl acetate, and vinyl chloride was carried out in the presence of water with nickel peroxide as a solid radical initiator. It was found that the rates of polymerizations of the monomers markedly increased with the presence of water, except in the case of styrene, and the molecular weights of the polymers obtained in water were higher than those obtained in toluene. The accelerating effect of water was closely related to the solubility of the monomer used in water. The stereoregularities of the polymers resulting from methyl methacrylate, however, were observed to be rather random. The effects of some organic and inorganic reducing agents on the rate of polymerization of methyl methacrylate or styrene initiated by nickel peroxide, and on the molecular weight and the stereoregularity of the resulting polymers were also investigated.

ISSN:0022-233X    

DOI:10.1080/10601326708053785

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

The reaction of substituted benzoic acids, dicarboxylic acids such as phthalic, terephthalic, and isophthalic acids, and the sodium or potassium salts of these acids with equimolar or excess epichlorohydrin in the presence of benzyltrimethylammonium chloride has been studied using various solvents such as toluene, dioxane, monochlorobenzene, and tetrachloroethylene. Use of the free carboxylic acids gave only fair to low yields of glycidyl esters, while sodium or potassium salts of the carboxylic acids gave excellent yields of materials of high oxirane content. The epoxidation of chlorohydrin esters of these acids by the dehydrochlorination was also studied using various dehydrochlorinating reagents such as NaOH, KOH, Na2CO3, and NaAlO2in such solvents as water, dichloromethane, dioxane, and monochlorobenzene at various temperatures. Reaction time, reaction temperature, and water content were found to influence the yield of glycidyl esters. It is suggested that the reaction path involves nucleophilic attack upon the terminal position of the epoxide or epichlorohydrin. The resulting alkoxide then reacts further to give either a glycidyl ester or a chlorine-containing by-product, the predominant course depending upon reaction conditions.

ISSN:0022-233X    

DOI:10.1080/10601326708053786

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

Poly(2,3-dimethylbutadiene-1,3) containingcis-1,4,trans-1,4, and 1,2 structural units in various proportions undergoes rapid oxidation even at room temperature. The process of oxidation is accompanied by cyclization. The concentration of peroxides that form at room temperature is relatively very high, reaching the value of one peroxidic group per 16 monomeric units. The formation of six-membered rings involving the peroxidic bonds in poly(2,3-dimethylbutadiene) is accompanied by degradation.

ISSN:0022-233X    

DOI:10.1080/10601326708053787

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

Several polymerization techniques were investigated to obtain high molecular weight polyacenaphthylene. Thermal polymerization was found to yield molecular weights of over 2,000,000.

ISSN:0022-233X    

DOI:10.1080/10601326708053788

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor

摘要:

To clarify the reaction mechanism of the solid-state polymerization of trioxane, the molecular weight distribution of polyoxymethylene is measured. High molecular weight polymer is precipitated around the stirrer in an early stage, then low polymer, while thep-chlorophenol solution of polyoxymethylene is violently rotated by a glass stirrer at about 60°C. To fractionate polymer, this phenomenon is applied for the polyoxymethylene produced in the solid-state polymerization catalyzed by BF3·O(C2H5)2inn-hexane medium at 40 and 50°C. The polymer obtained at a low conversion contains a large amount of high polymer part, and the amount of high polymer decreases with increasing conversion. It is estimated that high polymer is produced only at the initial stage of the polymerization and that the decrease of molecular weight of polymer at a high conversion in the solid-state polymerization may be due to the formation of low polymer at a high conversion and also to the degradation of high polymer during the polymerization.

ISSN:0022-233X    

DOI:10.1080/10601326708053789

出版商:Taylor & Francis Group    

年代:1967

数据来源: Taylor