Effect of Comonomer Ethylene on Plateau Modulus of Crystal-line Ethylene-propylene Random Copolymer with Broad Molecular Weight Distribution

✍ Scribed by Ding Jian; Xu Ri-Wei; Ding Xue-Jia; Yu Ding-Sheng

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 78 KB
• Volume: 23
• Category: Article
• ISSN: 0256-7660
• DOI: 10.1002/cjoc.200590665

✦ Synopsis

Abstract

Ethylene‐propylene random copolymer with ultra‐high molecular weight (UHPPR) and broad molecular weight distribution (MWD) was prepared with Ziegler‐Natta catalyst. The viscoelastic behavior of UHPPR has been investigated by means of oscillatory rheometer at 180, 200 and 220 °C. The loss modulus (G″ curves of 180 and 200 °C present a pronounced maximum at 38.10 and 84.70 r/s, respectively. For the first time, this makes it possible to directly determine the plateau modulus ($G^{0}_{N} $) of crystalline ethylene‐propylene random copolymer with broad MWD in a certain experimental temperature G″(ω) curve. The plateau modulus of UHPPR is 4.51×10^5^ and 3.67×10^5^ Pa at 180 and 200 °C respectively, increasing with random incorporation of comonomer ethylene into the molecular chains and being independent of molecular weight.