Shape Memory Properties of Short-Glass Fiber Reinforced Epoxy Composite Programmed below Glass Transition Temperature

A Shape Memory Polymer Composite (SMPC) is developed by reinforcing an epoxy-based polymer with randomly oriented short glass fibers. Diverging from previous research, which primarily focused on the hot programming of short glass fiber-based SMPCs, this work explores the potential for programming below the glass transition temperature (Tg) for epoxy-based SMPCs. To mitigate the inherent brittleness of the SMPC during deformation, a linear polymer is incorporated, and a temperature between room temperature and Tg is chosen as the deformation temperature to study the shape memory properties. The findings demonstrate an enhancement in shape fixity and recovery stress, alongside a reduction in shape recovery, with the incorporation of short glass fibers. In addition to tensile properties, thermal properties such as thermal conductivity, specific heat capacity, and glass transition temperature are investigated for their dependence on fiber content. Microscopic properties, such as fiber-matrix adhesion and the dispersion of glass fibers, are examined through Scanning Electron Microscope imaging. The fiber length distribution and mean fiber lengths are also measured for different fiber fractions.