New insights into crosslinking of elastomers through photo-oxidation

The impact of peroxides and their decomposition on crosslinking has been investigated in photo-ageing of a diene polymer. We report on the use of melt viscoelasticity, in addition to specific chemical treatments and analysis, applied to polyoctenamer photoageing. We show evidence that the intrinsic reactivity of (hydro)peroxides is responsible for the crosslinking observed in both natural and accelerated ageing of diene polymers like polyoctenamer. We emphasise the low critical peroxide species content which is determined as only about 10 mmol/kg. Finally, while we undoubtedly refute the hypothesis of peroxide crosslinks, we propose, on the basis of our experimental results and literature data, that the chemical nature of the junctions could be C-C or C-O-C bonds. (C) 2002 Elsevier Science Ltd. All rights reserved.