Characterization of impact propylene-ethylene copolymer

This paper studied composition, sequential structure, relative molecular mass and its distribution, heat transition, phase structure and macroscopic properties of overseas impact ethylene-propylene copolymers by means of temperature rising elution fractionation (TREF), nuclear magnetic resonance spectrometer, differential scanning calorimeter, gel permeation chromatograph and scanning electron microscope. The results confirm that the impact copolymer consists of homopolypropylene, ethylene-propylene rubber (EPR) and crystallizable ethylene-propylene copolymer, featuring superior mechanical properties. The homopolypropylene and EPR endue the impact copolymer with stiffness and toughness, respectively. The relative molecular mass of the impact copolymer possesses polydispersity and wider distribution. EPR has higher relative molecular mass and exists in the shape of particulate with diameter of 1-2 micrometer homogeneously dispersed in the polypropylene matrix, and thereby benefiting rise in impact strength of the impact copolymer. In addition, the impact copolymer also has higher melting point and heat resistance.