Modeling the solvent-induced shape-memory behavior of glassy polymers
We present a constitutive model for the effect of solvent absorption on the thermomechanical properties and shape-memory behavior of amorphous polymers. The absorption of low concentrations of solvent depresses the glass transition temperature by increasing the molecular mobility of the polymer chains. In a shape-memory application, this can lead to premature shape recovery and significant alterations to the time-dependence and temperature-dependence of shape recovery. We implemented the constitutive model for finite element analysis and developed a computational model that considered the time-dependent effect of diffusion to study the solvent-induced shape-memory behavior of a meth(acrylate) copolymer network. The model was validated by comparing to isothermal shape recovery experiments of specimens in air and water at different temperatures.