Analytical and Experimental Analysis of the Shape Recovery Behavior of Continuous Fiber Reinforced Shape Memory Polymer

Abstract

Shape memory polymer (SMP) signify a new category of responsive polymers characterized by their capability to undergo significant shape changes and then revert to their initial shape when exposed to specific stimuli. They are known by their low mechanical properties; however, when integrated into fiber-reinforced composites a considerable characteristics enhancement is achieved. Modeling the thermomechanical behaviour of these materials is crucial task to understand their shape fixity and recovery. However, the available models in the literature are sophisticated and not easy to implement. In this study a simplified mathematical model is presented, based on the stimulus temperature-time relation, to determine the shape recovery action in a woven glass fiber (GF) reinforced styrene based SMP. The model is validated using experimental investigations done with DMA Q800 analyser and a specially designed bending recovery tool where a slight deviation of (8%-16%) was achieved. The model findings showed significant reduction in recovery time of 25% and 41% when the fiber content increased from 20% to 25% and 30%, respectively. This makes the proposed model a valuable tool for engineers to assess the shape memory behavior. Experimental findings indicated that fiber reinforcement led to a significant enhancement in thermomechanical properties represented by 5oC increase in glass transition temperature and five orders of increase in storage modulus. Also, a remarkable improvement in shape recovery rate of up to 80% is obtained, however there is a slight reduction of (8% - 16%) in the shape fixity property.