Elastocaloric effect in poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) terpolymer

摘要

The elastocaloric properties of poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE)] terpolymer were directly characterized using an infrared imaging camera. At a strain of 12%, a reversible adiabatic temperature variation of 2.15 ℃ was measured, corresponding to an isothermal entropy variation of 21.5 kJm~(-3) K~(-1) or 11Jkg~(-1)K~(-1). In comparison with other elastocaloric materials, P(VDF-TrFE-CTFE) appears to represent a trade-off between the large required stresses in shape memory alloys and the large required strains in natural rubber. The internal energy of the P(VDF-TrFE-CTFE) polymer was found to be independent of the strain, resulting in complete conversion of the mechanical work into heat, as for pure elasto-meric materials. The elastocaloric effect therefore originates from a pure entropic elasticity, which is likely to be related to the amorphous phase of the polymer only.