X-ray Diffraction Patterns of Sol, Gel, and Total Rubber when Stretched, and when Crystallized by Freezing and from Solutions

Abstract

Abstract Sol, gel, and total rubber were prepared by a method which avoided the effects of light and oxygen. The total rubber when stretched and exposed to an x-ray beam behaved like other specimens, and produced the characteristic crystal fiber pattern. Stretched sol rubber produced no evidence whatever of this pattern, even at 1000 per cent elongation. With stretched gel rubber, the pattern was formed above 100 per cent elongation and at 200 per cent was sharp and intense. The measurements of interplanar spacings agree excellently with the results reported recently by Lotmar and Meyer. A large, interplanar spacing of 54 A. U. was found in the unstretched gel. It was absent in the sol. Specimens of frozen sol, gel, and total rubber were examined with a cylindrical and with a flat-film camera to compare the spacings and intensities with those of stretched gel. Within experimental error, sol, gel, and total rubber produce similar patterns. The spacings are similar to those in stretched rubber, with the exception of the (002) spacing in frozen rubber, which is 6.18 A. U. instead of 6.30 A. U., the value in stretched rubber. The pattern of gel, crystallized from solution, is similar to the patterns of stretched and frozen rubber.