Carbon fiber reinforced shape memory epoxy composites with superior mechanical performances

For the shape memory polymers' (SMPs) applications in demanding, high performance scenarios are usually limited by their poor mechanical performances during shape transformation. In this work, shape memory epoxy composites (SMEPCs) with superior mechanical properties are fabricated by adding various short and continuous carbon fibers (CFs) into neat shape memory epoxies (SMEPs) matrix. The resultant SMEPC's storage modulus (E^’) at room temperature is as high as 37 GPa, and the maximum recovery force exceeds 4.4 GPa, with good shape memory capabilities. These properties are at least an order of magnitude higher than those in existing typical SMP systems. The excellent mechanical properties of the fibers and their ability to retard crack propagation in the matrix are believed to play an important role in achieving high moduli below and above the shape-memory triggering temperature. The potential applications of such SMEPCs are demonstrated with wind blades. Experimental results and numerical models regarding air flow velocity variation as initiated by shape change in the blades indicate that our SMEPCs can sustain continuous stable mechanical state and provide variable wind speeds. These CF reinforced SMEPCs can be employed as smart structural materials to automatically switch shapes in response to the change in environment, such as those seen in aero foils and energy harvesters.