Effect of PEG-600 Incorporation on the Mechanical and Thermal Response of Tunable Fiber-Reinforced Shape Memory Polymer Composites

Abstract

Shape memory polymer composites (SMPCs) are an intelligent class of materials capable of self-actuation, offering promising applications in diverse stimuli-responsive material systems. This study developed epoxy-based SMPCs reinforced with carbon–aramid fibers at a 15:85 ratio, with their glass transition temperature (Tg) tailored by incorporating 5 wt.% (SMPC-5) and 10 wt.% (SMPC-10) polyethylene glycol (PEG-600). Dynamic mechanical analysis (DMA) confirmed that PEG addition effectively reduced the Tg from 89.79 °C in the neat composite (SMPC-P) to 70.28 °C in SMPC-5 and 59.34 °C in SMPC-10. Incorporating 5 wt.% PEG enhanced storage and loss moduli, whereas excessive plasticization at 10 wt.% reduced stiffness. Infrared spectroscopy analysis revealed shifts and increased intensities in hydroxyl (OH), aliphatic C-H, and carbonyl (C=O) groups, indicating enhanced intermolecular interactions and bond formation. Tensile testing showed that the carbon–aramid filler significantly improved tensile strength and stiffness, with SMPC-10 achieving the highest tensile strength (233.59 MPa) and SMPC-5 the highest Young’s modulus (14.081 GPa). These results highlight the complementary role of carbon–aramid reinforcement and PEG plasticization in tuning thermomechanical behavior, providing baseline insights for designing SMPCs with tailored actuation and reliable structural performance.