Low-Temperature-Toughened Polypropylene Blends with Highly Packed Elastomeric Domains

Abstract

Despite its versatility, the use of polypropylene (PP) has been limited to subzero temperature applications owing to its inherent brittleness at low temperatures. Herein, we introduce a PP ternary blend toughened by tailoring the domains of ethylene-propylene rubber (EPR) and poly(ethylene-co-octene) (EOC) within a PP matrix. The PP ternary blend was fabricated by melt-blending a PP and EOC binary mixture; a PP copolymer (PPC) was used as an additive. The Izod impact strength of the PP ternary blends dramatically increased between −50–20 °C compared to that of the iPP/EOC binary blend. Particularly, PP ternary blends with specific compositions exhibited impact strengths above 70 kJ/m2 even at −40 °C. The retraction rate of these blends was similar to that of high-performance specialty rubbers. Moreover, the blends exhibited a low brittleness temperature of −72.9 °C and, hence, may replace the expensive rubber products currently used for various low-temperature applications.