Process Parameter Optimization for Interfacial Performance of CFRT Foam Core Sandwich Structures via Microcellular Injection Overmolding

ABSTRACT This study focuses on the interfacial performance optimization of continuous fiber‐reinforced thermoplastic (CFRT) foam core sandwich structures manufactured via microcellular injection overmolding. In this integrated molding process, foamed polypropylene (PP) core is directly bonded to continuous glass fiber‐reinforced polypropylene (CGFR‐PP) skins. The interfacial performance plays a critical role in determining the mechanical performance of sandwich structures. Given the complexity of the molding process and challenges in controlling interfacial performance, a Box–Behnken experimental design combined with response surface methodology (RSM) was employed to investigate the effects of key processing parameters on Mode I and Mode II interfacial fracture energies. Double cantilever beam (DCB) and end‐notched flexure (ENF) tests were conducted to characterize the interfacial fracture energy. Regression models were developed and validated through analysis of variance (ANOVA), revealing that melt temperature and preheating temperature were the most influential factors, while interaction effects involving injection velocity and foaming agent content also played a significant role. Multi‐objective optimization identified the optimal processing window that maximized both Mode I and Mode II fracture energies, providing valuable guidance for processing the high‐performance composite sandwich structures.