Devatha P. Nair1, Neil B. Cramer2, Christopher N. Bowman2,3, Michael B. Lyons1, Bryan A. Rech1, Robin Shandas1,4,5

Shape memory polymers are a class of materials that can be programmed to respond to specific stimuli in their environment. By designing polymer systems that use body temperature as a trigger, it is possible to deliver shape memory polymer-based medical devices in a minimally invasive manner to the target location where, on being exposed to the temperature trigger, they can ‘switch’ to their final shape. Although it is possible to increase the tensile strength and modulus of the shape memory polymer by varying the formulation of the system, any increase in strength in the polymer is observed at the expense of a reduction in elongation of the system. An increase in the modulus and tensile strength of the base polymer without compromising the elongation of the system can result in a wider range of design, functionality and manufacturing options for the composite polymer. Utilizing a reinforced or composite shape memory polymer aids in the ability to manufacture shape memory devices without compromising the critical shape memory effect. Fiber-reinforced composites (FRCs) are often made for applications that call for high strength and stiffness in relation to weight. In general, this translates to a high tensile strength over a relatively large temperature range and a high modulus of elasticity, thereby increasing the manufacturing options for the material. A fiber reinforced polymer (FRP) composite is one in which the dispersed phase is a fiber and the matrix phase a polymer. The mechanical properties of Fiber Reinforced Polymers depend on the individual material properties and on the degree of division of the applied load between the two materials. The factors that work to improve the tensile strength of the composite include a strong interface between the matrix and the fiber, the presence of low stress concentration points and fiber orientation. This study examines longitudinally placed fibers in a polymer matrix loaded uni-axially along the longitudinal axis of the fiber. The fibers chosen for the study were based on their acceptability as proven biocompatible polymers. The purpose of this research is to tailor the thermomechanical and mechanical characteristics of an acrylic based shape memory polymer system to aid in the design and manufacture of Fiber-Reinforced shape memory polymer medical devices. We show that by reinforcing the base acrylic shape memory polymer with a range of biocompatible fibers, it is possible to considerably enhance the tensile strength and modulus of the composite without compromising the elongation of the base polymer, while maintaining its shape memory properties.

1-Department of Mechanical Engineering, University of Colorado, Boulder,

2-Department of Chemical and Biological Engineering, University of Colorado, Boulder,

3-Department of Restorative Dentistry ,University of Colorado Health Sciences Center,

4-Division of Cardiology , University of Colorado Health Sciences Center

5-Center for Bioengineering, University of Colorado Health Sciences Center