ELECTRON-MICROSCOPIC INVESTIGATION OF THE MOLECULAR MECHANISM OF PLASTIC-DEFORMATION OF POLYETHYLENE AND ISOTACTIC POLYSTYRENE CRYSTALS

In the reported experiments, the molecular process involved in the plastic deformation of crystals of linear polyethylene and isotactic polystyrene by necking was investigated by transmission electron microscopy (TEM). The results for the draw ratio, the height, and the shape of the neck and the molecular structure of the deformed material suggest that plastic deformation occurs basically by the unfolding and bending of the molecules in a deformation region only a few nm wide. The observations are at variance with deformation models involving complete unfolding of the molecules or the breaking off of folded-chain blocks and the incorporation of these blocks into the deformed material.