Shape memory polyurethane for structural applications

Polyurethane polymer demonstrates a wide range of mechanical properties due to unique and broad molecular structure of the prepolymer. One of the major areas that have been the focus of research community for the last two decades is developing polyurethane foam for shape memory applications. Shape memory polymers are a category of polymers which respond to stimulus such as temperature, moisture or impact, and are able to go through a deformed temporary state and return to their original shape. Polyurethane has the hard segment of diurethane and soft segments of diisocyanate-coupled polyester or polyether chains, which makes it capable of shape recovery. The original research and development on shape memory polyurethane has been with a focus on its shape recovery characteristics for medical or outer space applications, however for structural or semi-structural applications in Automobile industry such as a self-healing car bumper the ability to regain the original mechanical properties is also important. This chapter reviews the state of the art in research on shape memory polyurethane structure and its thermo-mechanical as well as mechanical properties. With focus on structural applications, this review also includes the research and development in applications of reinforcing fibers on shape memory polyurethane and its effect on the structure and shape recovery properties. In addition, this chapter provides the state of the research in cyclic loading responses for durability and reliability of polyurethane in actuation applications.