Modification of substandard EPDM with amorphous thermoplastic polyesters (PETG and PEF): microstructure and physical properties

The phase morphology, thermal behavior and mechanical properties of two series of polymer blends based on ethylene/propylene/diene rubber (EPDM) and amorphous homologues of poly(ethylene terephthalate), i.e. glycol modified poly(ethylene terephthalate) (PETG) and poly(ethylene furanoate) (PEF), were investigated. The morphology of the blends shows a two phase structure in which the minor phase (amorphous polyester) is dispersed as domains in the major (EPDM) continuous matrix phase. Differential calorimetry studies confirmed that both systems were immiscible and exhibits two glass transitions. The melting peak area of EPDM in the blends decreased as the amount of the other component increased. The values of stress at strain of 100% were improved upon the increasing content of PETG in EPDM system, while only slight decrease of this value was observed. Moreover, the strong improvement of hardness and thermo-oxidative stability along with an increasing content of amorphous polyester phase was reported.