✦ LIBER ✦

DSC and 13C NMR studies of ethylene-propene copolymers prepared by a highly active and stereospecific catalyst

✍ Scribed by Xuequan Zhang; Hui Chen; Zinan Zhou; Baotong Huang; Zhanwang Wang; Ming Jiang; Yongran Yang

Publisher: John Wiley and Sons
Year: 1994
Tongue: English
Weight: 444 KB
Volume: 195
Category: Article
ISSN: 1022-1352
DOI: 10.1002/macp.1994.021950321

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

Ethylene‐propene copolymers (EPR) were synthesized at different feed compositions using a highly active and isospecific MgCl~2~‐supported Ti‐based catalyst. The thermal behavior of EPR was studied by differential scanning calorimetry, the heterogeneity by fractionation, and the chain structure by ^13^C NMR using the method of substituent chemical shift. The results show that EPR of very low crystallinity (1,0 wt.‐%) can be obtained at high propene content in the feed with a heptane‐insoluble fraction of only 0,9 wt.‐%. Thus, a high isotacticity in propylene sequences and a high randomness in EPR can be achieved at the same time, and producing high‐impact poly(propylene) in a reactor is possible with this catalyst. Sequence distribution and length distribution of ethylene sequences indicate that EPR is produced at multiple active sites, and each site is dominated not only by a first‐order Markovian model but also by unsteady diffusion factors.

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