The effect of crosslinking and miscibility on the thermal degradation of an uncured and an amine-cured epoxy resin blended with poly(ε-caprolactone)

The results of an investigation concerning the thermal behaviour of an uncured and an amine-cured diglycidyl ether of bisphenol-A (DGEBA) epoxy resin blended with poly(epsilon-caprolactone) (PCL) are reported. The nature and extent of degradation were analysed by means of integral (TGA) and derivative (DTG) thermogravimetry. The decomposition kinetics of both uncured and cured blends were elucidated by the Coats and Redfern equation. Pure PCL has been seen to be more thermally stable than uncured DGEBA, but more unstable than cured DGEBA. For uncured blends, thermogravimetric curves clearly displayed more than one degradation step, while for the cured blends essentially a single weight loss step was observed. The cured blends showed enhanced thermal stability and char formation when compared to the corresponding uncured ones of identical DGEBA/PCL ratio. Besides, it has also been evidenced that although the uncured blends are miscible and the cured ones are immiscible, both systems exhibited negative deviations of the apparent activation energy from the additivity rule. (C) 2002 Elsevier Science Ltd. All rights reserved.