Mechanism of large deformations of crystalline polypropylene over a wide temperature range

Abstract

SINCE the earliest investigations into the nature of the high-elasticity of rubber, s tudy of the mechanism of large deformations of polymers has been based on ideas related to the flexibility of macromolecules and on the resultant transitions in the configurations. Moreover it was thought that large deformations could develop either in the region of the high-elastic state of polymers, or in the region of the glass-like state under the action of large mechanical forces (forced elasticity). In the latter case also, the development of large deformations was again determined by the flexibility of the macromolecules. The object of this paper is to describe several new experimental factors arising from study of large deformations of crystalline polymers, in this case using polypropylene, over a wide raiige of temperatures. As will be demonstrated below, the development of large deformations can occur also under conditions where the flexibility of the macromoleeules is completely suppressed and the deformation process takes place at a supermoleeular level.