Elevating Polycarbonate Performance: Exploiting In-situ Nanofibrillated and Crosslinked Ethylene Propylene Diene Monomer Networks to Achieve Superior Material Properties

Abstract

The incorporation of an elastomer into polymer composites is a widely employed method to enhance toughness; however, this often results in the sacrificed crucial matrix properties, such as stiffness and strength. In this study, an efficient composite technology is presented for enhancing the toughness of polycarbonate (PC) with a marginal sacrificing of stiffness and strength. Initially, PC-spherical ethylene propylene diene monomer (EPDM) blends were prepared using a twin-screw extruder (TSE), followed by a hot stretching process in a spunbond system. The produced PC microfibers containing EPDM nanofibrils were exposed to gamma radiation to effectively crosslink EPDM through ethylidene norbornene (ENB) and thereby preserve the nanofibril geometry, while crosslinking the PC phase slightly. Morphological observations of the reheated blends revealed a well-dispersed, crosslinked nanofibrillar EPDM network within the PC matrix, featuring an average diameter of 40-80 nm. Our study investigates the influence of EPDM nanofibril size and content on PC composites. We found that incorporating nanofibril EPDM significantly improves toughness compared to spherical EPDM phases, with over 300% increase in elongation at break and over 200% increase in Izod impact strength. These findings highlight the efficacy of nanofibril EPDM in advancing PC's mechanical properties, offering promising prospects for polymer engineering. The transparency of PC was maintained with the presence of nanofibril EPDM, making it suitable for various transparent applications.