Structural Formation of Cyclic Olefin Copolymer (COC) Films as Revealed by Real Time Retardation Measurements during Fast Stretching Process

Abstract

This work reports on an experimental study of the fast stretching of a cyclic olefin copolymer (COC) film. We measured the stress retardation of the polymer film during fast stretching and identified a relationship between stress and birefringence. This relationship indicates that the film obeys the stress optical rule (SOR) at the onset of stretching. At slower stretching speeds, the stress optical constant (SOC) settles at a certain value. With faster stretching speeds, SOC values approach the photo-elastic constant (PEC). Our study also investigated the effects of stretching temperatures and stretching modes for both uniaxial stretching and biaxial stretching. We applied techniques of thermal analysis to evaluate higher order structures after fast stretching.