Fractionation and molecular characterization of EPDM rubbers

✍ Scribed by O. Chiantore; P. Cinquina; M. Guaita

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 277 KB
• Volume: 30
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(94)90196-1

✦ Synopsis

A~tract--A sample of EPDM rubber containing 61.4 wt% of ethylene units, 27.2 wt% of propylene units and 11.5 wt% of ethylidene norbornene units, dissolved in diphenylmethane, has been separated into 20 fractions by slowly cooling from 160 to 50°C (temperature gradient fractionation). It is shown by SEC, tH-NMR analysis and viscometry that the fractions have decreasing molecular weight, and practically the same diene units content as the unfractionated sample. As to ethylene and propylene units, their content is constant in fractions separated at temperatures lower than 105°C, whereas the fractions obtained at the highest temperatures contain larger amounts of propylene units, suggesting that some peculiar step in the polymerization process might yield high molecular weight, propylene rich, molecules.