A cluster model for the polymer amorphous state

Some aspects of local order in the amorphous state of a glassy polymer are discussed. The physical principles behind a cluster model involving the new concept of a structural defect are presented. A comparative analysis of three major approaches to describing the amorphous state of a polymer is given. It is shown that the cluster model is in reality a unified model which presents a new explanation for many qualitative results produced in the past on polymer structure and processes involved and which, unlike previous approaches, has the advantage of being quantitative. Possible future directions in polymer structure studies are outlined.