Thermo-mechanical properties of shape-recoverable structural composites via vacuum-assisted resin transfer molding process and in-situ polymerization of poly (tert-butyl acrylate-co-acrylic acid) copolymer

When selecting a polymer matrix to make shape memory polymer composites (SMPCs), it is crucial to consider high elastic modulus below the switching temperature ($T_{\mathrm{sw}}$), a significant variation in the modulus above $T_{\mathrm{sw}}$, and the ability to control $T_{\mathrm{sw}}$. This research introduces shape-recoverable structural composites fabricated from poly (tert-butyl acrylate-co-acrylic acid) (PtBA-AA), which has a significant modulus variation before and after $T_{\mathrm{sw}}$. Capillary numbers are assessed to minimize void formation at varying acrylic acid (AA) concentrations, which regulate the copolymer’s polarity and the thermo-mechanical properties. The glass transition temperature of PtBA-AA can be adjusted from 47.4 °C to 91.6 °C. Furthermore, the elastic modulus of SMPC increases from 13 GPa to 20 GPa, whereas the tensile strength increases from 526 MPa to 889 MPa. The maximum recovery strength measured 100.4 MPa at an AA molar ratio of 0.23, accompanied by a fixity of 89.1 % and a recovery ratio of 97.2 %.