A new method for predicting the thermal oxidation of thermoset matrices - Application to an amine crosslinked epoxy

The thermal oxidation of an aromatic amine crosslinked epoxy network has been studied in air below its glass transition temperature by optical microscopy, IR spectroscopy and gravimetry. The superficial oxidised layer has a thickness of 147 mum at 150 degreesC, 94 mum at 180 degreesC and 62 mum at 200 degreesC. A method is proposed to predict the oxidised thickness. It is based on a differential equation in which O-2 diffusion and its chemical consumption rate, r(C), are coupled, C being the O-2 concentration. The knowledge of equation parameters requires two sets of experiments: permeation tests to estimate both O-2 diffusivity and solubility into the polymer and also, gravimetric measurements on thin polymer films oxidised at various O-2 partial pressures to determine the kinetic parameters of r(C). Predictions are in good agreement with experimental results for all temperatures under consideration. (C) 2001 Elsevier Science Ltd. All rights reserved.