Crosslinking of elastomers upon ageing: a kinetic approach based on crystallinity changes followed by DSC

It was observed that crosslinking reactions resulting both from peroxide decomposition or photoageing at wavelengths longer than 300nm involve a drastic decrease of the crystallinity of some dienic elastomers, such as polybutadienes (rich in cis 1,4 and 1,2 microstructures) and polycyclooctene. By comparing precisely the rate of decomposition of dicumyl peroxide and that of the crystallinity decrease, it was possible to show that the kinetics of crystallinity loss observed upon ageing can be identified with that of the crosslinking of elastomers. The results indicate that the crosslinking process can be followed directly by DSC measurement of the crystallization/melting cycle. (C) 2003 Society of Chemical Industry.