Application of Taguchi design method to formulate sizing agents enhancing basalt fiber tensile strength and adhesion to thermoplastic polymers

Abstract Basalt fiber (BF)‐reinforced thermoplastic polymers (TPs) show great potential by leveraging their recyclability. Sizing agents are crucial in optimizing BF quality and aiding polymer impregnation during production. However, the absence of established guidelines for sizing agents tailored to thermoplastic BFs persists. This study investigates the effects of sizing agent ingredients on the mechanical and surface properties of BFs under industrial conditions. The Taguchi method was used to formulate nine BF sizing agents, predominantly incorporating polypropylene (PP) emulsion, epoxy or polyurethane emulsion, silane coupling agents (SCAs), and additives. Our investigation extends to evaluating the tensile strength, surface roughness, and wetting characteristics of individual BFs. Results indicate that a heightened PP concentration enhances BF adhesion to TPs but concurrently reduces BF tensile strength. Furthermore, using SCA, specifically dodecyltrimethoxysilane, leads to a remarkable enhancement of approximately 20% in BF tensile strength and an impressive 40% in BF adhesion to TPs. This study unravels sizing agent intricacies, illuminating their nuanced interplay with the work of adhesion rooted in fiber and polymer surface energy. Our work offers innovative solutions to optimize BF‐reinforced thermoplastic polymers. Highlights Investigating thermoplastic sizing agent formulations for basalt fibers (BFs) Guiding formulation of BF sizing agents with the Taguchi Method. Predicting contact angles between BFs and commonly used thermoplastic polymers. PP emulsions favor BF‐thermoplastic polymer adhesion but not BF tensile strength.