The Fine Structure of Crystallized Rubber

Whereas in the unstretched state rubber gives on examination by x-rays the diagram of a liquid, in the stretched state it gives a well-defined fiber diagram. This was first described by Katz in 1925. Since that time the crystalline interferences of rubber have been studied by several investigators. The first classification of these interferences was undertaken by Hauser and Mark, who arranged them in the form of a rhombic lattice. Later, working with a thin film of highly stretched rubber, Mark and von Susich succeeded in obtaining preparations with a higher degree of orientation. According to whether it was irradiated parallel or perpendicular to the surface of the film, such a preparation showed different intensities of the reflections. In this way Mark and von Susich succeeded in obtaining a different and more reliable indication of the reflections than did Hauser and Mark. Mark and von Susich found a rhombic elementary cell with axes of 8.3 ± 0.1 A. U., 8.1 ± 0.1 A. U. (fiber axis), and 12.3 ± 0.1. A. U. On the basis of their better established elementary cell, Mark and von Susich developed a space model of rubber which agreed fairly well with the largest intensity effects. In constructing this model they relied on the assumption expressed by Meyer and Mark that primary valence chains of the formula: