Prediction of tensile modulus based on parameters of crystalline structure in polyethylene terephthalate with cold crystallization ability

Abstract

This work aims to adopt a simple modulus prediction method for the crystalline poly(ethylene-terephthalate) (PET), which has strong cold-crystallization ability. Based on a single melting curve generated by calorimetry, crystallinity and average melting temperature can easily be evaluated and consequently, tensile modulus can be predicted. Nonetheless, in the case of polymers with cold crystallization behavior, such as PET, the melting process is affected by cold crystallization, impeding the simple calculation of the aforementioned important parameters. In this paper, the techniques to eradicate cold crystallization during calorimetry are presented. Accordingly, the results of a tensile modulus prediction model are presented and discussed. The crystallization and melting characteristics of PET were measured by differential scanning calorimetry (DSC). The mechanical properties of the specimens were estimated by standardized tensile tests. The specimens, which were used for mechanical tests were fabricated using conventional injection molding. The samples were annealed at different temperatures in order to obtain different crystalline structures. The results clearly indicate that the prediction technique is capable to describe the tensile modulus of PET accurately in the case of very diverse crystalline structures.

Keywords

• Mechanical properties
• Prediction model
• poly(ethylene terephthalate)
• Melting curve
• Cold crystallization