摘要:

Abstract(1) A study of the four sulfur atoms in tetramethylthiuram disulfide (TMTD) by radiosulfur techniques disclosed that these sulfur atoms are equivalent chemically. (2). The synthesis and reactions of radio‐TMTD were studied. (3) New reactions which were found for TMTD included those with the following substances: dimethylamine,n‐dodecyl mercaptan, ZnS, ZnO, zinc dust, S8*, and acetic acid. (4) Radiosulfur and the sulfur atoms in ZnDMDC do not undergo interchange, at least up to 1

ISSN:0022-3832    

DOI:10.1002/pol.1951.120060101

出版商:Interscience Publishers, Inc.    

年代:1951

数据来源: WILEY

摘要:

Abstract(1) A technique has been described for the short‐path distillation of substances from rubber. It has been found that sulfur, TMTM, TMTD, ZnDMDC, phenyl‐beta‐naphthylamine, and palmitic acid are recoverable by this procedure. (2) The conversion of zinc compounds such as zinc oxide and zinc palmitate to ZnDMDC in rubber by treatment first with CS2and then with dimethylamine has been studied. (3) The volatilization of zinc from vulcanizates after conversion to ZnDMDC has been shown to occur without devulcaniz

ISSN:0022-3832    

DOI:10.1002/pol.1951.120060102

出版商:Interscience Publishers, Inc.    

年代:1951

数据来源: WILEY

摘要:

Abstract(1) The reaction of rubber with zinc palmitate was found to liberate palmitic acid at low pressures, thus revealing that rubber is acidic. (2) The reaction of zinc oxide with palmitic acid in toluene solution was enhanced by the presence of water. (3) The small increase in the nitrogen content of rubber caused by its reaction with TMTD was equivalent to the palmitic acid liberated by the zinc palmitate reaction. (4) The use of TMTD as a reagent for organic acids has been studied and found to convert carboxyl groups into dimethylamide groups. This result suggests that the acidic nature of rubber is due to carboxyl groups in the rubber molecule, a suggestion which is compatible with the nearly complete removal of zinc from the TMTD vulcanizate by the zinc removal technique.

ISSN:0022-3832    

DOI:10.1002/pol.1951.120060103

出版商:Interscience Publishers, Inc.    

年代:1951

数据来源: WILEY

摘要:

AbstractThe construction of a modified form of osmotic balance has been described. By suspending a cell from each arm, the instrument has been made insensitive to temperature changes. In place of weighings, measurements are recorded by altering the buoyancy of one of the cells. By the use of an optical lever in conjunction with a divided photo‐ cell, a considerable increase in sensitivity has been obtained, the movements of the balance pointer being magnified about 300 times. A new method of matching the levels of solvent and solution has been described. Difficulties due to evaporation of solvent are discusse

ISSN:0022-3832    

DOI:10.1002/pol.1951.120060104

出版商:Interscience Publishers, Inc.    

年代:1951

数据来源: WILEY

摘要:

AbstractIn this paper a new method for the preparation of cyclized rubber from natural rubber latex is described. In this method, which follows logically from the new way of preparing rubber hydrochloride from natural rubber latex, latex stabilized with nonionic or cationic emulsifying agents is mixed with sulfuric acid. If a sufficient amount of sulfuric acid is added, cyclized rubber is formed after some heating. The influence of sulfuric acid concentration and the temperature on the rate of reaction have been investigated. Other cyclizing agents proved to be hydrogen fluoride and boron trifluoride. The advantage of the method described is that cyclized rubber can be obtained in the form of a latex.

ISSN:0022-3832    

DOI:10.1002/pol.1951.120060105

出版商:Interscience Publishers, Inc.    

年代:1951

数据来源: WILEY

摘要:

AbstractThe measurement of the heats of dissolution of cellulose of diverse percentages of We crystallization has permitted us to find the heat of crystallization of the cellulose. We have found 4100 cal./mole. This number is about 25% less than the heat of crystallization of the beta‐glucose and it is very near that which had been found by one of the authors by means of the heats of wetting. The knowledge of the heats of crystallization of the cellulose and the determination of the heats of dissolution make possible the determination of the percentage of crystallization of a sample of cellulose when the composition of the sample in reference is know

ISSN:0022-3832    

DOI:10.1002/pol.1951.120060106

出版商:Interscience Publishers, Inc.    

年代:1951

数据来源: WILEY

摘要:

AbstractA brief discussion of the importance of the transfer step and its effect in the pyrolysis of polyethylene is given. In this case the removal, by molecular distillation, of smaller species from the reacting mixture modifies the kinetics. The molecular weight decreases less rapidly and tends to a limiting value depending on the maximum size of the evaporating molecules. The number distribution of the latter is, in a first approximation, independent of their size. The pertinent expressions are presented and the general solution of the rate equations which can be used to obtain higher approximations is given.

ISSN:0022-3832    

DOI:10.1002/pol.1951.120060107

出版商:Interscience Publishers, Inc.    

年代:1951

数据来源: WILEY

摘要:

AbstractThe results of emulsion polymerizations in which twenty‐eight different organic hydroperoxides were used as oxidizing agents in a standard redox recipe at 5°C. have been presented. Each hydroperoxide was tested at several different concentration levels. The hydroperoxides of chlorodiisopropylbenzene, di‐t‐butylisopropylbenzene, cyclohexylbenzene, 1,2,3,4,4a,9,10,10a‐octahydrophenanthrene, andt‐butylisopropylbenzene were found to be the most effective of the compounds tested. Oxidation mixtures, concentrates of oxidation mixtures, and purified samples of hydroperoxides served as sources of hydroperoxide for the polymerization experiments reported. Similar results were obtained with oxidation mixtures and concentrates, but purification of the hydroperoxide usually resulted in improved polymerization rates. The amount of hydroperoxide which gives the optimum results in a given polymerization recipe varies for structurally different hydroperoxides and appears to be related to the molecu

ISSN:0022-3832    

DOI:10.1002/pol.1951.120060108

出版商:Interscience Publishers, Inc.    

年代:1951

数据来源: WILEY

摘要:

AbstractThe introduction of the Dioxes as oxidants in emulsion polymerizations at subfreezing temperatures has opened up new horizons especially in the direction of the utilization of commercially available rosin acid soaps in formulations containing low iron concentrations. It is now possible to copolymerize butadiene and styrene to 60% conversion in 16 hours in an emulsion recipe containing only 0.3 millimole of iron per 100 g. of monomers with Diox*D, Dresinate 214, and potassium soap flakes; formerly it had been impossible to reach such a conversion within 24 hours. By the use of mixed potassium laurate‐ myristate emulsifier and Diox 7, a conversion of 60% with a fluid latex was achieved in 119 hours at −10°C. In order to attain these high rates of conversion, it is necessary that the redox components of the polymerization recipe be properly “balanced” with respect to the mole ratio of oxidant to iron, and that the potassium chloride concentration in the activator and thepH of the emulsifier solution be adjusted to their optimu

ISSN:0022-3832    

DOI:10.1002/pol.1951.120060109

出版商:Interscience Publishers, Inc.    

年代:1951

数据来源: WILEY

摘要:

AbstractThe rate of emulsion copolymerization of butadiene‐styrene (75:25) has been studied at 50°C. as a function of the amount of soap. The following soaps were investigated: potassium myristate, potassium laurate, sodium caprate, sodium salt of dispropor‐ tionated rosin acids, and a commercial soap (largely sodium palmitate, oleate, and stearate). The initial rate of polymerization is decreased as the amount of soap is decreased, but the rate after about 25% conversion becomes almost independent of the amount of soap. If the concentration of soap in the aqueous phase is less than the critical concentration for micelle formation the initial rate is extremely small and becomes about equal to the rate in the absence of emulsifier. The initial rate with varying amounts of different detergents is approximately proportional to the amount of solu‐ bilization by the soap or other detergent solution. The data confirm Harkins' theory that solnbilization by soap micelles is a major factor in the initial stages of emulsion polymeri

ISSN:0022-3832    

DOI:10.1002/pol.1951.120060110

出版商:Interscience Publishers, Inc.    

年代:1951

数据来源: WILEY