title: Reduced time as a unified parameter determining fixity and free recovery of shape memory polymers.
abstract: Shape memory polymers are at the forefront of recent materials research. Although the basic concept has been known for decades, recent advances in the research of shape memory polymers demand a unified approach to predict the shape memory performance under different thermo-temporal conditions. Here we report such an approach to predict the shape fixity and free recovery of thermo-rheologically simple shape memory polymers. The results show that the influence of programming conditions to free recovery can be unified by a reduced programming time that uniquely determines shape fixity, which consequently uniquely determines the shape recovery with a reduced recovery time. Furthermore, using the time-temperature superposition principle, shape recoveries under different thermo-temporal conditions can be extracted from the shape recovery under the reduced recovery time. Finally, a shape memory performance map is constructed based on a few simple standard polymer rheology tests to characterize the shape memory performance of the polymer.
authors.affiliation: Department of Mechanical Engineering, University of Colorado, UCB 427, Boulder, Colorado 80309, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Yu
authors.affiliation: Department of Mechanical Engineering, University of Colorado, UCB 427, Boulder, Colorado 80309, USA.
authors.forename: Qi
authors.initials: Q
authors.lastname: Ge
authors.affiliation: Department of Mechanical Engineering, University of Colorado, UCB 427, Boulder, Colorado 80309, USA.
authors.forename: H Jerry
authors.initials: HJ
authors.lastname: Qi