X-Ray Diffraction Patterns of Crystalline Sol Rubber Prepared from Ethereal Solution

Abstract

Abstract In a previous publication there was reproduced an x-ray diffraction pattern of crystals obtained from a solution, cooled to temperatures between −40° and −50° C, of an ether-gel fraction of rubber from Hevea brasiliensis. Measurements of three strong interferences indicated that the crystals were similar to those of stretched gel rubber and of frozen sol, gel and total rubber. Although many attempts were made at that time, unsatisfactory diffraction patterns were obtained with crystalline ether-sol rubber. The interferences were faint and not suitable for accurate measurement and analysis. Since the crystalline material is bulky and some specimens are more compact than others, it seemed possible that the average number of cell diameters was too small to permit sharp definition, and that more material was required for the examination by x-rays. However, it is not certain that lack of definition was caused by insufficient crystalline rubber. The possibility that parts of the long-chain molecules become crystalline and that parts remain amorphous is not excluded, and might be its cause. Additional work with crystalline sol rubber, using a slightly different experimental procedure and more material than in earlier experiments, finally resulted in a satisfactory pattern.