Effect of structure on the deformation and failure of oriented polymer films

Abstract

This study compares the effect of anisotropic structure on the room temperature (23°C) deformation and failure behavior of two distinctly different polymers. One a single phase nematic polymer, PMDA-ODA polyimide [PI] with a glass transition, T g , near 400°C; the other a previously studied anisotropic two phase molecular polymer composite, isotactic polypropylene [IPP] with a glass transition near 14°C. Although isotactic polypropylene has a two phase crystal-noncrystalline structure its deformation behavior is controlled by the noncrystalline phase. A series of oriented PMDA-ODA polyimide [PI] films are fabricated and their orientation characterized. The present study investigates whether the deformation and failure behavior of these anisotropic single phase nematic PMDA-ODA polyimide films (tested at a very low strain rate at room temperature) is similar to that previously observed for isotactic polypropylene at its low strain rate failure envelope limit.