A phenomenological formulation for the shape/temperature memory effect in amorphous polymers with multi-stress components

Abstract

By means of combining the influence of temperature and strain rate, and based on the cooperative Eyring model, a phenomenological formulation for the shape memory effect and temperature memory effect of an amorphous shape memory polymer (SMP) is proposed. The internal stress and stored mechanical energy are correlated to shape/temperature memory behaviours below and above the glass transition temperature. The working mechanism and fundamentals for the chemo-responsive shape memory behaviour in SMPs are further investigated in terms of the activation enthalpy parameter for inductive depression. Simulation using the proposed model is compared with the experimental results reported in the literature. Predictions are also made using the proposed model. This phenomenological framework is expected to provide a powerful tool for investigating the underlying thermomechanics that originate in the movement of cooperative segments and segmental relaxations in SMPs.

Shape Memory-Enhanced Electrical Self-Healing of Stretchable Electrodes

“…Heating at 80 • C for several minutes triggered obvious shape recovery, along with the process of which the stretchable electrode was capable of healing the conductive pathways, enabling the lamp to enlighten again. and stored mechanical energy were found to be correlated to the shape/temperature memory behavior below and above the transition temperature [14]. It is well known that the Tm-type shape memory polymers, exhibited the so called stress-memory effect [15,16].…”

“…The spectra results indicated that the release of the strain energy magnified micro-structural variations in the shape memory-enhanced self-healing process. The internal stress and stored mechanical energy were found to be correlated to the shape/temperature memory behavior below and above the transition temperature [14]. It is well known that the T m -type shape memory polymers, exhibited the so called stress-memory effect [15,16].…”

A thermomechanical model of multi-shape memory effect for amorphous polymer with tunable segment compositions

“…In comparison with other types of soft materials such as electroactive elastomers and hydrogels, SMPs have unique and desirable shape memory capabilities owing to the pre-stored mechanical energy during the pre-deformation stage [4,5]. In terms of thermodynamics, SMP macromolecules are normally composed of two or more segments, at least one of which is the hard segment and the others of which is soft one [6,7]. A cooperative relaxation could happen between the hard and soft segments at temperatures below and above the glass transition temperature [6][7][8].…”

“…In terms of thermodynamics, SMP macromolecules are normally composed of two or more segments, at least one of which is the hard segment and the others of which is soft one [6,7]. A cooperative relaxation could happen between the hard and soft segments at temperatures below and above the glass transition temperature [6][7][8]. Therefore, shape memory behavior of amorphous SMPs has been theoretically explained based on the thermo-visco-elasticity effects, and the mobility changes in the macromolecules has been linked to the changes in the viscosity or relaxation time using rheological elements [9,10].…”

“…However, it is not straightforward to model the multi-SME due to its complex and dynamic transition of the segment composition [18][19][20][21][22][23][24][25]. Theoretical studies have previously been proposed to model and predict the multi-SME based on different molecule structures and cooperative relaxation [6,7]. In these pioneer studies, the constitutive relations were typically based on a specific modeling frame.…”