Universal Cure-Induced Shrinkage Model Applied to an Epoxy Amine as a Method to Optimize Composite Processing Time, Shrinkage, and Residual Stress

Presented here is an investigation into the experimental and predicted shrinkage during cure of a rapid curing epoxy/cycloaliphatic amine system. A volumetric shrinkage model that considers chemical shrinkage, thermal and physical changes, and cure conversion is proposed and used to estimate the dependency of shrinkage on resin cure. Kinetic parameters determined using the Kamal-Sourour autocatalytic model enabled the prediction of shrinkage for any cure profile. The developed model provides an important tool for the identification of time- and temperature-dependent shrinkage within increasing cure conversion and growth of network properties such as glass transition temperature. Finally, the model is used to predict shrinkage during different post-cure scenarios, which highlight its value in designing cure profiles that potentially minimize residual stress. Molecular dynamics simulations are used to predict the glass transition temperature, the conversion at gelation, and overall shrinkage during cure and provide excellent support to experimental findings.