Subcritical Crack Growth at a Polymer/Glass Interface

Abstract

ABSTRACTSubcritical crack growth at polymer/glass interfaces can occur due to a stress dependent chemical reaction at the crack tip at a crack driving force less than the critical fracture energy for catastrophic crack propagation. A four—point flexure apparatus coupled with an inverted microscope allows observation in situ of the subcritical crack growth at the polymer/glass interface. The specimen consists of soda—lime glass plates bonded together with epoxy acrylate. In the four—point flexure test, the strain energy release rate is independent of the interfacial crack length. This test technique allows for subcritical crack growth at the polymer/glass interface to be measured as a function of the applied crack driving force and relative humidity. The results are discussed in terms of a fracture mechanics model.