Partially constrained recovery of (meth)acrylate shape‐memory polymer networks

Abstract

The purpose of this study was to characterize the partial strain recovery of a thermoset shapememory polymer under a constraining stress. Three polymer networks were synthesized from tert-butyl acrylate and poly(ethylene glycol) dimethacrylate (PEGDMA) solutions. The molecular weight and the weight fraction of the PEGDMA crosslinking monomer was altered systematically to maintain a constant glass transition temperature (T g ¼ 54 C) but tailorable rubbery moduli, which varied by almost an order of magnitude for the three polymer networks (E 0 r ¼ 1.8-11.3 MPa). The shape-recovery behavior of the polymers under a constraining stress was characterized for programming temperature below (20 C) and above (70 C) the T g . The experiments revealed a peak in the recovered strain for samples programmed at 20 C. Recovered strain scaled linearly with the constraining stress by the rubbery modulus. The work performed by the shape-memory polymer networks was observed to be primarily a function of constraining stress and crosslinking density, while programming temperature had a relatively mild influence; however, the efficiency of the shape-memory effect was shown to be a function of constraining stress and programming temperature, but was independent of crosslinking density. Maximum work efficiencies (up to 45%) were observed for programming temperature of 70 C. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 126: 72-82, 2012

Reversible plasticity shape memory polymers: Key factors and applications

“…Lakhera et al found that, under high constraining stresses, the samples programmed below T trans showed a peak in the recovered strain, close to the T trans , followed by a reduction with continuously increasing temperature. However, this behavior was not occurred in samples programmed above T trans . The sufficient release of high internal strain energy of RPSM is responsible for the peak strain around T trans , which is not observed in samples programmed above T trans .…”

Thermo-mechanics of Amorphous Shape-memory Polymers

“…Section 2 presents the major assumptions of the modeling approach and main constitutive relationships. Section 3 describes applications of the models to study the effect of deformation temperature [12,13,8], physical aging [14,9] and solvent absorption [6] on the shape-memory behavior, as well as the mechanism of multiple shape-memory effects [15].…”

Adhesion behavior of polymer networks with tailored mechanical properties using spherical and flat contacts

“…The BA-co-XLS networks were thoroughly mixed and then solidified by UV-induced free-radical polymerization using 0.1% DMPA photoinitiator. [14][15][16][17][18] The low-strain thermomechanical properties of the samples were characterized by dynamic mechanical analysis (DMA, TA Instruments Q800DMA, New Castle, DE). These samples were thermally equilibrated at −80°C for 5 min and heated to 40°C at a rate of 2°C/min while subjected to a 0.1% dynamic tensile strain at 1 Hz.…”