The molecular orientation and mechanical properties of poly(ethylene terephthalate) under uniaxial extension

Abstract

AbstractThe molecular orientation, induced crystallization, and mechanical properties of amorphous poly(ethylene terephthalate) (PET), stretched at different temperatures and strain rates, were studied. The results indicate that the orientation parameter [P2(cosθ)] of oriented PET varies strongly with both temperature and strain rate, but the strain‐induced crystallinity seems dependent on temperature only. It was also found that as draw ratio increased, the Young's modulus, yield stress, and necking ratio were greatly improved in the stretching direction, but slightly declined in the transverse direction. A rubber network model was used to make a quantitative description of the orientation development with draw ratio. © 1993 John Wiley & Sons, Inc.