Orange-Peel-Inspired Interfacial Structures Engineered via Bénard-Marangoni Convection for Mechanical Enhancement of Basalt Fiber-Reinforced Epoxy and Polyphenylene Sulfide Composites

Basalt fiber, as an eco-friendly high-performance material, finds application across diverse fields. The issue of low interfacial adhesion in basalt fiber-reinforced thermoplastic and thermosetting composites is drawing increasing attention. This study presents a one-step and nanoparticle-free fiber sizing strategy that constructs orange-peel-inspired interfacial architectures for both basalt fiber/epoxy resin (BF/EP) and basalt fiber/polyphenylene sulfide (BF/PPS) composites. Polyborosiloxanes (PBSs) sizing agents were synthesized via an atomizer-assisted hydrolysis–polycondensation reaction, and orange-peel-inspired coatings were formed on fiber surfaces by inducing Bénard-Marangoni convection. PBS coatings formed interfacial mechanical interlocking, while simultaneously constructing interfacial chemical bonding via their functional groups. Owing to differences in interfacial bonding mechanisms and matrix properties between BF/EP and BF/PPS composites, PBSs with varying boron contents influenced their mechanical properties and interfacial failure modes differently, resulting in 60%, 18% and 17% improvements in flexural strength, modulus, and interlaminar shear strength of BF/EP composites, and 28%, 6% and 22% enhancements in the corresponding properties of BF/PPS composites, respectively. Introducing Bénard-Marangoni convection into sizing technology enables convenient and efficient implementation, with promising practical applications.