Gases in the Reaction of Phenylmagnesium Bromide with Halides 493 copper were found to be ineffective as catalysts anethole hydrobromide and Grignard reagents, in the synthesis of hexestrol dimethyl ether from Chicago, Illinois

This investigation was carried out under the sponsorship of the Office of Rubber Reserve, Reconstruction Finance Corporation, in COMeCtiOn with the U. S. Government synthetic rubber program. t Present address:

The fine structures of emulsion polybutadiene prepared at temperatures ranging from 55°C. to −20°C. and of various butadiene‐styrene copolymers prepared at −20°C. have been studied by x‐ray methods. The ability of emulsion‐polymerized butadiene to crystallize was found to depend to a large extent on the temperature of polymerization. Butadiene polymerized at 30°C. and above showed no evidences of crystallization when cooled unstretched to −70°C. as observed by x‐ray diffraction methods; however, butadiene polymerized at 20°C. and below showed crystallization effects when cooled unstretched to −70°C. These crystallization effects became more pronounced for samples polymerized at lower temperatures. Layer‐line diffraction patterns of butadiene polymerized at 30°C. and below were obtained by stretching the polymer at about 0°C. From these patterns the geometrical repeat distance along the polymer chains was found to be 5.1 ± 0.1 Å. This corresponds to a fully extended butadiene unit in the trans configuration. An anomaly was observed in the diffraction patterns of crystallizable polybutadiene stretched at 0°C. Some of the layer‐line spots varied in position with per cent elongation of the sample. This suggests that the molecules in crystallites of the polymer are inclined to the stretch axis at low elongations and that they become more nearly parallel to the stretch axis at higher elongations. A small addition of styrene as comonomer at −20°C. polymerization temperature did not prevent crystallization and preferred orientation effects in the polymer, since these effects could still be found in a 90/10 charge copolymer. Larger amounts of styrene did prevent crystallinity and preferred orientation as shown by the amorphous nature of an 80/20 charge copolymer. The ability of a compounded vulcanizate of a given polymer to crystallize is less than that of the purified polymer under the same conditions. This may be due to the combined effects of milling, vulcanization, and the presence of carbon black particles in the polymer. A description of the apparatus and techniques used for cooling and stretching these polymers is given.

Although it is now generally recognized that the temperature of polymerization affects profoundly the properties of emulsion elastomers, there is very little evidence available pertaining to the cause of the variations of properties. It is felt by some that the improved properties of low-temperature elastomers can be related to variations in molecular weight and molecular-weight distribution. In this laboratory, however, the opinion has prevailed that the lower emulsion polymerization temperatures appreciably alter the fine structure of the molecules with an increase in the regularity of the polymer chains. If there were actually less branching and cross-linking in low-temperature polymers, and less 1,2-addition to monomer components, the increased order should be evident from x-ray diffraction patterns. To provide information on the above questions, x-ray studies were made with four purposes in view: (1) to determine the effect of polymerization temperature on the crystallization properties of unstretched and stretched polybutadienes; (2) to determine the influence of styrene content on the crystallization of butadiene-styrene copolymers; (3) to study some effects of compounding and vulcanization on crystallizable polybutadiene; and (4) to use the preferred orientation patterns obtained from some of these polymers for structural evaluations. To accomplish these objectives, x-ray patterns were obtained at several temperatures of some unstretched and stretched polybutadiene polymers, butadiene-styrene copolymers, and a vulcanized and compounded polybutadiene. The polybutadienes were prepared by emulsion polymerizations at 55°, 40°, 30°, 20°, 5°, −10° and −20° C. Since the −20° C polybutadiene showed the most marked crystallization patterns, the effects of compounding and of styrene addition were studied, using polymers prepared at this temperature for comparison. Three butadiene-styrene copolymers containing, respectively, 10, 20, and 30 per cent styrene in the monomer charge and one vulcanized polybutadiene compounded with Wyex carbon black were studied.

The 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, and t‐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 molecular weight.