CRYSTALLIZATION SEGREGATION DSC STUDIES OF PP/PE COPOLYMERS

The structural analysis of two PP/PE copolymer samples, I and 2, was conducted by using 13C-NMR, GPC and crystallization segregation DSC (CSDSC) techniques. A pure polypropylene sample was also used for comparison. It was found that the two copolymer samples are very close in composition (the ethylene mol content is 4.3% and 4.5%,respectively), stereoregularity (96% and 97%) and molecular weight (Mw, = 7.0 x 104 and 7.3x104; Mw/Mn = 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 temperature and a broader distribution of its thermogram. These phenomena were explained as an indication of a less uniform distribution of ethylene units along the PP chains for sample 1. It was noted that CSDSC is a very sensitive and convenient technique for structural studies of copolymers.