Tough shape-memory polymer—fiber composites

Abstract

This study describes a multi-faceted materials selection problem that ultimately produces a new class of polymer—fiber composites with failure strains of near 400% and ultimate tensile strengths (UTS’s) up to 20 MPa. Independent control of the rubbery modulus (proportional to the compressive force the composite can apply) is demonstrated by altering the crosslinker density of the polymer matrix and the fiber weave. The stress the composite can withstand can be modified with changing fiber material and weave geometry. The resulting SMP—fiber composites can be designed with glass transition temperatures (T_g’s) ranging from 0°C to 75°C, and specific multi-layer combinations of these systems provide a promising candidate for orthopedic casts: specifically, a woven anteres nylon lycra mesh rigidized with a polymer synthesized from methyl acrylate, butyl acrylate, isobornyl acrylate, and trimethylol propane triacrylate. The results of this study are intended to enable future orthopedic applications where the ability to accurately and independently position T_g and the ability to tune recoverable force in toughened, fiber-reinforced SMPs are required.