Tuning viscoelastic properties of VHB 4910 elastomers for artificial muscles

Abstract

Understanding the tunable viscoelastic behavior of dielectric elastomers for artificial muscles is important to regulate the electromechanical actuation, response time, energy density, sensitivity, duty cycle, etc. However, the performance of elastomers is well known to be regulated by varieties of filler particles, crosslinkers and plasticizers, the influences of particulate fillers on the viscoelastic behavior of VHB 4910 elastomer are yet to be recognized. In this work, a new range of particulate-polymer filled VHB elastomers are prepared to study the effects of barium titanate and Ketjenblack particles on the viscoelastic properties. This followed the experimental characterization of stress-relaxation and creep behavior to realize the time-dependent mechanical performance. Also, stress-softening and energy dissipation behavior are considered to find the number of cycles required to reach the equilibrium energy state. Significantly reduced viscoelastic properties including elastic modulus, toughness, energy density and hysteresis are recognized as a result of diminished poroelastic effects owing to the filled polymer. In contrast, the variations in stress/strain values are evidenced to depend on the interfacial free energy and size of the particulates. Theoretical comparison of these results with the mechanism of biomedical materials confirmed the feasibility of the modified elastomers in the field of artificial muscles and soft robotics. This work may help in recognizing the strategies to tune the viscoelastic behavior of VHB dielectric elastomers reliant on sets of applications.