Investigation of cure induced shrinkage in unreinforced epoxy resin

Changes in volume and thermal expansion coefficient have been investigated during the cure of a high temperature curing epoxy resin containing a thermoplastic modifier. The measurements were carried out using a combination of standard and novel thermoanalytical techniques. It is shown that the chemical shrinkage of the curing resin is a linear function of the degree of cure, whereas the coefficient of thermal expansion depends on the temperature and on the degree of cure. This experimental information is translated to an incremental model that simulates the volumetric changes occurring as the resin follows a programmed thermal profile. Such a model can serve as a density submodel in simulating heat transfer or residual stress development in composites during the manufacturing process.