Photodegradation of poly[ethylene-co-propene-co-(5-ethylidene-2-norbornene)] rubbers, 2. Physical and dynamic-mechanical behaviour under accelerated conditions

✍ Scribed by Marco Scoponi; Fiorella Pradella; Vittorio Carassiti; Davide Tartari

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 521 KB
• Volume: 195
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1994.021950316

✦ Synopsis

Abstract

The physical and dynamic‐mechanical behaviour during the photo‐oxidation under accelerated conditons of three poly(ethylene‐co‐propene‐co‐5‐ethylidene‐2‐norbornene) (EPDM) rubbers with different contents of 5‐ethylidene‐2‐norborneneSystem. name: 5‐ethylidenebicyclo[2.2.1]hept‐2‐ene.

(ENB) are reported. These results show the dependence of the glass transition temperature both on the ENB content and on the photo‐oxidation time in accordance with network formation in the rubber matrix under accelerated conditions. The tensile experiments also show an increase of the elastic modulus as function both of ENB content and of photo‐oxidation time. The Murayama and Mooney‐Rivlin equations are applied to estimate the average molecular weight between two crosslinking nodes occurring in the rubber matrix during photo‐oxidation with tensile and dynamic‐mechanical experiments, respectively. Some correlations of physical and dynamic‐mechanical changes with the proposed mechanism of photo‐oxidation, due to the formation and reactivity of unsaturated groups, show that the crosslinking processes prevail over chain scissions.