CHARACTERIZATION OF IMPACT POLYPROPYLENE COPOLYMERS BY SOLVENT FRACTIONATION

The compositional heterogeneity of two impact polypropylene copolymers (IPCs) was studied by a combinatory investigation of temperature rising elution fractionation (TREF) and solvent fractionation. The chain structures and composition of fractions obtained from solvent fractionation were examined in detail. The TREF results shows that there are much more E-P segmented copolymer and more uniform distribution of ethylene sequence in IPC-1, which is responsible for its better comprehensive mechanical performance. The fractions from hexane and heptane are ethylene-propylene rubber phase and E-P block copolymers respectively. The result of solvent fractionation method also shows that custom hexane or heptane extractions can not extract the E-P copolymer completely.