Processing Induced Superstructures in Moulded Amorphous Polymers

Abstract

Although HOUWINK [1] suggested already in 1936 the existence of colloidal superstructures in amorphous polymers newly developed methods of electron microscopic preparation techniques allow in the recent years for the first time to obtain direct evidence of well defined morphologies in many high polymers. So for example it was possible to show in the case of atactic polystyrene [2], styrene/ acrylonitrile copolymer [3], polyethylene terephthalate [4], poly-carbonate [4] and polymethyl methacrylate [5] that the isotropic and slightly oriented states are characterized by globular network structures; the highly oriented materials posses a line by line structure. Geometrical shape and regularity of the morphology only depend on the degree of molecular orientations, but not on the way producing themselves by varying the hotstretching parameters. Therefore similar relationships can be assumed between morphological changes and processing induced molecular orientations in injection moulded polymers.