Photodegradation of poly[ethylene-co-propene-co-(5-ethylidene-2-norbornene)] rubbers, 1. Reappraisal of the photo-oxidation mechanism under accelerated conditions

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

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 554 KB
• Volume: 195
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1994.021950315

✦ Synopsis

Abstract

In this work the reexamination of the photo‐oxidation mechanism of three poly(ethylene‐co‐propene‐co‐5‐ethylidene‐2‐norbornene) (EPDM) terpolymers containing different amounts of 5‐ethylidene‐2‐norbornene (ENB)System. name: 5‐ethylidenebicyclo[2.2.1]hept‐2‐ene.

(2‐8 wt.‐%) is discussed. The photo‐oxidation depends on the initial content of ENB units in the chains. The formation of a band at 923 cm^−1^ is attributed to the CH out‐of‐plane deformation of a new double bond in terminal position in the ethylidene moieties. The presence of double bond migration suggests the formation of stable tertiary hydroperoxides which show a new band at 870 cm^−1^. The kinetic behaviour of a band with similar spectral pattern in the UV at 235 nm has been correlated with double bond migration. The identification of photoproducts both by 2,4‐dinitrophenylhydrazin and SO~2~ confirms the proposed spectroscopic assignments. The gel measurements of the studied terpolymers, and some comparisons with a poly(ethylene‐co‐propene) (EPR) copolymer having a similar ethylene to propene ratio, suggest that the presence of ENB can strongly influence both the photo‐oxidation and the crosslinking yields of these rubbers.