P. Cortes et al., ADDITION OF A REACTIVE DILUENT TO A CATALYZED EPOXY-ANHYDRIDE SYSTEM .2. EFFECT ON ENTHALPY RELAXATION, Journal of applied polymer science, 63(1), 1997, pp. 17-25
Enthalpy relaxation in an epoxy resin based on diglycidyl ether of bis
phenol A (DGEBA) with a reactive diluent cured with methyl-tetrahydrop
hthalic anhydride (MTHPA) with an accelerator was investigated by diff
erential scanning calorimetry. The reactive diluent (RD) added was an
aliphatic diglycidyl ether which was mixed in a proportion of 50 parts
by weight (pbw) per 100 parts of DGEBA, with the stoichiometric quant
ity of MTHPA. The key parameters of the enthalpy relaxation investigat
ed were the nonlinearity parameter, x, the apparent activation energy,
Delta h, and the nonexponentiality parameter, beta. The results were
compared with other data obtained previously in similar epoxy-anhydri
de systems without an RD but with different degrees of conversion in o
rder to analyze the effects of (a) the introduction of aliphatic chain
s of the RD in the epoxy structure and (b) a reduction in the crosslin
k density of the resin. (C) 1997 John Wiley & Sons, Inc.