Multiscale modeling of residual deformation in CFRP with reaction-induced phase separation

In carbon fiber-reinforced plastic (CFRP) used for structural components, the addition of thermoplastic resins to epoxy resin enhances toughness by leveraging the reaction-induced phase-separated structure formed during curing. Despite substantial research on phase-separated resins, limited studies have explored the residual deformation of composite materials using these resins as the matrix. This study experimentally and numerically evaluated the residual deformation of CFRP containing a reaction-induced phase-separated structure. Molding experiments were performed to evaluate the effects of thermoplastic resin addition on the thermomechanical properties of the epoxy resin and residual deformation of its composite. Furthermore, multiscale modeling that can account for the use of phase-separated resin as matrix was constructed to predict the process-induced residual deformation. The experimental results revealed that thermoplastic resin addition improved the thermomechanical properties, particularly by mitigating cure- and thermal shrinkage, which are primary drivers of residual deformation. Interestingly, phase separation had a negligible effect on the reaction behavior of the thermoset resin. Consequently, the process-induced residual deformation of the composite laminate was reduced. The proposed multiscale modeling accurately captured the reduced cure shrinkage and the changes in the matrix resin’s thermomechanical properties. Moreover, the predicted residual deformation aligned closely with experimental observations, enabling a comprehensive understanding and integrated discussion of the hierarchical characteristics of the phase-separated resin composites. These findings provide critical insights for advancing the development of high-performance composite structures and optimizing manufacturing processes. • Thermoplastic resin addition effectively reduced residual deformation in CFRP. • Suppression of cure and thermal shrinkage reduced residual deformation. • Multiscale modeling predicted deformation in composites with phase-separated matrix. • Multiscale modeling revealed hierarchical features across different scales.