Oxidation induced shrinkage for thermally aged epoxy networks

摘要

The matrix oxidation of composite materials involves a weight loss and a density increase and as a consequence, a shrinkage of the skin layer of the material. To simulate this behaviour, we chose a kinetic model of radical chain oxidation coupled with the equation of oxygen diffusion. This model predicts the concentration profile of oxidation products, the weight loss profile and the shrinkage profile in a thick part. When the stress field induced by shrinkage reaches a critical value (the ultimate stress of the oxidized polymer), a "spontaneous" cracking appears in the skin layer of thick parts. In order to predict these critical conditions, we determined the mechanical properties of the oxidized layer of thick parts by studying the ageing of matrix thin films for which oxidation is not controlled by the oxygen diffusion. (C) 2003 Elsevier Science Ltd. All rights reserved. [References: 10]