AUTHORS: Guoqiang Li, WeiXu
ABSTRACT:
Programming is a key process for thermally activated stress or strain recovery of shape memory polymers(SMPs). Typically, programming requires an initial heating above the glass transition temperature(Tg), subsequent cooling below Tg and removal of the applied load, in order to fix a temporary shape. This work adopted a new approach to program thermoset SMPs directly at temperatures well below Tg, which effectively simplified the shape fixing process.1-D compression programming below Tg and free
shape recovery of a thermoset SMP were experimentally investigated. Functional stability of the shape fixity under various environmental attacks was also experimentally evaluated. Amechanism based thermoviscoelastic–thermoviscoplasticconstitutive model incorporating structural and stress relaxation was then developed to predict the nonlinear shape memory behavior of the SMP trained below Tg. Comparison
between the prediction and the experiment showed good agreement. The structure dependence of the thermomechanical behavior of the SMP was further discussed through a parametric study per the validated constitutive model. This study validates that programming by cold compression is aviable alternative for thermally responsive thermoset SMPs.
ABSTRACT:
Programming is a key process for thermally activated stress or strain recovery of shape memory polymers(SMPs). Typically, programming requires an initial heating above the glass transition temperature(Tg), subsequent cooling below Tg and removal of the applied load, in order to fix a temporary shape. This work adopted a new approach to program thermoset SMPs directly at temperatures well below Tg, which effectively simplified the shape fixing process.1-D compression programming below Tg and free
shape recovery of a thermoset SMP were experimentally investigated. Functional stability of the shape fixity under various environmental attacks was also experimentally evaluated. Amechanism based thermoviscoelastic–thermoviscoplasticconstitutive model incorporating structural and stress relaxation was then developed to predict the nonlinear shape memory behavior of the SMP trained below Tg. Comparison
between the prediction and the experiment showed good agreement. The structure dependence of the thermomechanical behavior of the SMP was further discussed through a parametric study per the validated constitutive model. This study validates that programming by cold compression is aviable alternative for thermally responsive thermoset SMPs.
