Compatibilization of poly(lactic acid)/ethylene‐propylene‐diene rubber blends by using organic montmorillonite as a compatibilizer

Abstract

ABSTRACTThis work focuses on phase morphology and properties of immiscible poly(lactic acid)/ethylene‐propylene‐diene rubber (PLA/EPDM) blends compatibilized with organic montmorillonite (OMMT). Effect of OMMT loading on phase morphology, mechanical properties, and blown film bubble stability was investigated. Transmission electron micrographs show that a large number of OMMT nanolayers locate at interfacial region between PLA and EPDM phase, as well as in EPDM phase due to higher affinity of OMMT with EPDM. Scanning electron micrographs show that EPDM domain size decreases largely with increasing OMMT loading, which is associated with reduction of interfacial energy and inhibition of coalescence by the OMMT locating at the interface, acting as an emulsifier to enwrap the discrete domains. As OMMT loading increases from 0 to 1 phr, elongation at break increases from 20.4 to 151.7% and notched impact strength is enhanced from 8.2 to 31.7 kJċm−2. The reduced EPDM domain is the main reason for enhanced toughness of PLA/EPDM/OMMT samples according to crazing with shear yielding mechanism. However, with more than 2 phr of OMMT, the toughness decreases largely due to excessive stress concentration and OMMT aggregation. Attempts were made to produce ductile films from the PLA/EPDM/OMMT nanocomposites by using blown film extrusion. Improvement in blown film bubble stability and tensile ductility of PLA/EPDM/OMMT films also shows that OMMT is an efficient compatibilizer, as well as a processing aid for PLA/EPDM blends. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44192.