Multiscale framework for estimation of induced elastic properties of Poly ethylene terephthalate after biaxial elongation

During the stretch blow molding process, molecular chains are submitted to large biaxial elongations and the material Poly Ethylene Terephthalate (PET for short) is reinforced. In this study, thanks to SAXS measurements on PET bottles and on bi-axially stretched samples under the X-ray beam, we build a simple model to represent the induced microstructure. With a two-steps homogenization process managed quasi-analytically, we can predict the induced Young modulus. Compared to the measured modulus from the PET bottle, it has been shown that the amorphous phase does not remain isotropic and the properties of the amorphous phase can be identified.