Effects of Soft and Hard Fillers on Electromechanical Properties and Performance of Polydimethylsiloxane Elastomer for Actuator Applications

Abstract

Abstract Desired ratio of high relative permittivity and low elastic modulus limits the application of silicon rubbers in various engineering fields as flexible electromechanical actuators. The relative permittivity can be improved by incorporating varieties of high-k particles and polymer reagents as plasticizers and crosslinkers into elastomer matrix. The present work investigates the effect of polyethylene glycol flakes (PEG as plasticizer) and titanium boride (TB) particles (high-k particle) as soft and hard fillers respectively, on electromechanical (EM) properties of polydimethylsiloxane (PDMS) elastomer composite for soft actuators. Elastomer composites filled with various concentrations of fillers are created and labeled accordingly to distinguish impact of fillers on EM properties. Uniform dispersion for fillers is confirmed by FESEM, EDX, FTIR, and UV-Vis. Elastic modulus and relative permittivity are significantly influenced by filler contents for both fillers. Elastic modulus for lower concentrations (2 and 5 wt.%) of soft fillers (PEG) increases while 8 wt.% leads to as comparable to the base material (PDMS). Soft fillers (PEG) aid in maintaining low elastic modulus, whereas hard fillers (TB) increase electrical breakdown strength as well as dielectric loss with almost identical changes in relative permittivity for both composites. The maximum actuation strain of 30.8% and 26.2% is attained for an in-house fabricated linear actuator with 8 wt.% of PEG and TB particles, respectively. Methodology and results may be helpful in selection of fillers to improve the dielectric behavior of silicon elastomers depending on the acceptable range of their adverse effect on other properties.