Mechanical properties of steel fiber/PBAT composites: Orientation-dependent reinforcement and theoretical modeling

Steel fibers exhibit excellent elastic modulus and ultimate tensile strength values. Consequently, even small amounts of steel fibers in a polymer matrix can significantly improve its mechanical properties. This low fiber content means the composite's density isn't notably compromised, making them promising for use in composites. The steel fibers, in the form of a defined fabric created by weaving individual steel fibers together, were embedded into a Poly(butylene adipate-co-terephthalate) (PBAT) melt. Composites with varying fiber orientations were produced, and their mechanical properties were examined using Tensile Testing and Dynamic Mechanical Analysis (DMA). The embedding of steel fibers into a thermoplastic polymer matrix results in a particularly interesting material with regard to recyclability. Since the steel fiber mesh is woven from individual fibers rather than yarns, it provides a particularly interesting model system for comparing experiments with theoretical models, thereby helping to understand the fundamentals of fiber-reinforced materials. Tensile testing experiments clearly demonstrate the angle-dependent reinforcement effect of the steel fibers, while DMA measurements reveal the angle-dependent resistance of the fibers to material torsion. All these experimental results can be understood through theoretical models and thus enhance our understanding of such materials.