Property modeling across transition temperatures in polymers: application to thermoplastic systems

Abstract

The growing demand for virtual design of composite materials necessitates the development of comprehensive models relating the microstructure of the constituents to the macroscopic mechanical behavior. In this spirit, a new model was recently introduced that enables the computation of polymer stiffness over the entire range of use temperature (C. A. Mahieux and K. L. Reifsnider, Polymer 42(7) (2001) 3281). A preliminary study stated the feasibility of the approach and the apparent possibility of applying this model to all polymers. The present study investigated the possibility of applying the model to some commercial thermoplastics: PMMA, PEEK, PPS and AS4/PPS composite. Cryogenic DMA were performed and the properties (crystallinity and molecular weight) of the composites were systematically varied. The model was applied to the different materials. The influence of the chemical nature, the molecular weight and the crystallinity content on the model input was carefully studied. The molecular nature and molecular weight were found to have little influence on the statistical parameters; the statistical parameter associated with the glass transition was found to vary linearly with crystalline content for the semi-crystalline samples. The model was found to successfully represent the behavior of all of the polymer based systems considered in the present study.