Kinetic criterion for triple-shape memory effect in amorphous polymers undergoing heterogeneous glass transitions

Abstract

The triple-shape memory effect (triple-SME) in amorphous polymers arises from the heterogeneous glass transitions of different components. However, due to the complex composition and structural relaxation of triple-shape memory polymers (triple-SMPs), existing models struggle to characterize the shape memory temperature range for each component and its dependence on thermal history. This presents a challenge in developing a kinetic criterion to judge the occurrence of the triple-SME. To address this issue, we propose a kinetic phase transition model to predict the shape memory temperature range for each transition phase in triple-SMPs under different thermal histories. By combining the Tool-Narayanaswamy-Moynihan (TNM) model with the Adam-Gibbs theory, the effect of cooling rate during programming on subsequent triple-SME is investigated. Subsequently, the effectiveness of the proposed model is evaluated by applying it to predict the shape memory performance and thermomechanical behavior of SMPs with dual- and triple- SMEs under different thermal histories. Using this modeling strategy enables the calculation of the critical isothermal shape recovery time for each transition phase under different thermal histories, effectively preventing shape recovery overlap. Consequently, the proposed model is expected to provide theoretical guidance for designing SMPs with triple-SME and promoting their application in engineering.