Abstract
Homogeneously deformed amorphous poly(ethylene terephthalate) (PET) film samples were obtained by uniaxial drawing at temperatures from near the glass transition temperature T g to far above T g. Isothermal dimensional recovery behavior was studied for the free stress state of the deformed sample. It was shown that the dimensional recovery behavior of samples drawn near T g was different from that of a sample drawn about 20°C above T g, indicating that the deformation mechanisms changed when the drawing temperature rose from near T g to far above T g. Recovery curves of samples drawn near T g show two distinct steps in log time scale; the second step follows a single exponential function. The infrared measurement of a drawn sample showed that the dichroic function decreased during recovery in the first step and was almost invariant at a very low value (<0.03) in the second step. However, the recovery curve of samples drawn about 20°C above T g demonstrated nearly a straight line in log time scale.
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