This article reviews the main progress in the development of typical thermoset shape memory polymers. Thermoset polymers are usually stronger in their microstructure than thermoplastic polymers due to their covalently crosslinked three-dimensional networks. The virtues of thermoset polymers make them great source materials for shape memory polymers. However, their three-dimensional networks endow thermoset shape memory polymers with not only high shape fixity rates and shape recovery rates but also low deformation abilities and brittleness. In the past decade, many breakthroughs have been made regarding thermoset shape memory polymers. Typical thermoset materials, such as epoxy resin, cyanate resin, thermoset polyurethane, polyimide, and polystyrene, have been studied as raw materials for shape memory polymers. Studies on thermoset shape memory polymers have been carried out to not only improve their fundamental properties (i.e. broadening of their operating temperatures and service environments and enhancing their thermal stabilities and mechanical properties) but also introduce functional performance properties (e.g. responsiveness to light, electricity, magnetism, and chemical stimuli). This article aims to present a brief review of the development of thermoset shape memory polymers, including the selection and preparation of materials, the improvement of properties, the functionalization of their composites, and their potential applications.
In this article, the epoxy-based shape memory polymers were exposed to simulated γ-radiation environments up to 140 days for an accelerated irradiation. The influence of γ-radiation on thermal and mechanical properties was evaluated by differential scanning calorimetry, dynamic mechanical analysis, and tensile test. The glass transition temperatures ( Tg) determined by differential scanning calorimetry and dynamic mechanical analysis decreased no more than 10%, and the shape recovery speed became a little faster after γ-radiation of 1 × 105 Gy. The tensile strength and elastic modulus could, respectively, maintain 26 MPa and 1.36 GPa after being irradiated by 1 × 106 Gy radiation, showing great potential in aerospace structural materials.