Crystallization segregation DSC studies of PP/PE copolymers

The structural analysis of two PP/PE copolymer samples, 1 and 2, was conduc ted by using C-13-NMR, GPC and crystallization segregation DSC (CSDSC) tech niques. A pure polypropylene sample was also used for comparison. It was fo und that the two copolymer samples are very close in composition (the ethyl ene mol content is 4.3% and 4.5%, respectively), stereoregularity (96% and 97%) and molecular weight (M-w = 7.0 x 10(4) and 7.3 x 10(4); M-w/M-n = 5.0 and 6.1, respectively). While the CSDSC thermograms of the two samples are quite different from each other. Sample 1 shows a higher average melting t emperature and a broader distribution of its thermogram These phenomena wer e explained as an indication of a less uniform distribution of ethylene uni ts along the PP chains for sample 1. It was noted that CSDSC is a very sens itive and convenient technique for structural studies of copolymers.