Dual filler synergy in glass fiber-reinforced thermoplastic copolyester elastomer composites: A study on thermo-mechanical behavior

The low mechanical strength of thermoplastic copolyester elastomer (TCE) limits their use in structural applications. To improve thermal and mechanical performance, silicon carbide (SiC), polytetrafluoroethylene (PTFE), and short glass fiber (SGF) were used to strengthen TCE in this work. Injection molding and twin-screw extrusion were used for producing composites. Based on thermal analysis, hybrid SGF–PTFE–SiC improved char yield, altered melting and crystallization behavior, and raised the degradation temperature from 405.6°C to 423.9°C. According to dynamic mechanical research, 30 wt% SGF increased the loss modulus from 69 to 109 MPa (+58%) and the storage modulus from 1938 to 4066 MPa (+109%). Hybrid fillers further improved rigidity and decreased damping. Mechanical tests showed that 30 wt% SGF increased tensile strength to 76.49 MPa (+113%) and tensile modulus to 6.05 GPa (+212%); hybrid filler incorporation up to 40 wt% further increased impact strength by 35% and modulus to 6.75 GPa (+248%). Improved fiber-matrix adhesion was shown by SEM of broken surfaces; toughness was increased by fiber pullout, breaking, and decreased voids. These findings demonstrate the promise of SGF and hybrid-filled TCE composites for high-performance structural applications, such as lightweight engineering components, high-temperature load-bearing systems, and automotive components.