Subtle structural aspects of propylene-based copolymers as revealed by raman spectroscopy

Abstract

Raman spectroscopy is used to elucidate fine details of the rather complex microstructure of ethylene-propylene copolymers (EPCs). This paper is focused on a series of commercial EPCs (Versify by Dow) with well-characterized ethylene content. Particular emphasis is given on the analysis of crystal type and content and their relation with EPC chain microstructure. Information provided by Raman is compared with that obtained by differential scanning calorimetry (DSC), a well-established technique widely used in the polymer field. Temperature-resolved Raman experiments are also carried out to interpret more precisely the complex melting patterns observed in the DSC traces. These experiments reveal precisely the crystal chemical composition and melting temperature ranges of EPC samples, key features to design processing conditions that guarantee optimum lifetime and recyclability of overmolded parts.