Interfacial Performance of Carbon Fiber Reinforced Bismaleimide Composites with Different Sizing Agents Under High Temperature and Humidity Condition

Abstract

This study addresses the crucial need to understand the interfacial behavior of GQ4522 carbon fiber reinforced bismaleimide (BMI) resin under conditions of high temperature and humidity, with a particular focus on the role of sizing agents. Through an integrated characterization approach that includes scanning electron microscopy, atomic force microscopy and surface energy measurements, combined with mechanical testing, this research elucidates how sizing agents influence fiber surface topography, specifically by reducing groove depth and enhancing uniformity, which affects interfacial compatibility. Key findings indicate the optimal sizing content necessary for achieving a balance between resin infiltration and fiber protection. Notably, GQ4522-7# fiber demonstrates a higher surface energy (43.45 mN/m), which is beneficial for wetting, while GQ4522-8# fiber exhibits a uniform sizing distribution, despite the presence of surface protrusions attributed to high viscosity. Mechanical testing results reveal distinct compatibilities: 7# sizing agent increases the resistance to high temperature and humidity of BMI-I composites, whereas 8# sizing agent improves the mechanical performance of BMI-II composites. This work contributes foundational insights into the interplay between fiber surface characteristics and sizing chemistry, establishing pivotal benchmarks for the advancement of high-performance composites in aerospace applications.