Triple-shape memory effect in a styrene-based shape memory polymer: Characterization, theory and application

A segmented styrene-based shape memory polymer (SMP) comprising two types of SMP materials (S1-SMP and S2-SMP) was fabricated by using a two-step curing method to exhibit the triple shape memory effect (triple-SME). The material properties of S1-SMP and S2-SMP parts were explored using dynamic mechanical analysis, multi-frequency scan testing, thermal expansion measurements, static tensile testing and shape memory testing, respectively. Meanwhile, the triple-SME of segmented SMP was also characterized by shape memory testing with continue heating step. These experimentally determined material properties were incorporated into the theoretical model for the triple-SME based on a phase transition model and Generalized Maxwell model. Experimental verification was obtained by observing the triple-SME behavior under uniaxial tensile strain of 20%. Finally, the triple-SME behavior of SMP was assessed in two engineered implementations; a programmable self-deployed structure model and double bottle-shaped smart mandrel. Good agreement was demonstrated between experimental result and a finite-element model (FEM) simulation during the continue heating recovery step.