On the Origin of the Amorphous Component in Polymer Single Crystals and the Nature of the Fold Surface.

A model for the surface of folded-chain polymer single crystals is presented in which the "amorphous" phase is composed of polymer molecules physically adsorbed on surface sites of a fairly regularly folded surface. The evidence for the presence of an amorphous phase in polymer single crystals is reviewed briefly as well as the evidence for regular folding and adjacent reentry. The proposed model would allow simultaneous acceptance of the evidence for both an amorphous layer and a surface composed of regularly folded molecules; such evidence was heretofore contradictory. Experimental evidence for such a model is discussed and some predictions are made concerning the properties of such an adsorbed layer.