Tensile Modeling PVC Gels for Electrohydraulic Actuators

Plasticized polyvinyl chloride (PVC) gels are a fascinating dielectric elastomer actuator showing promise in soft robotics. When actuated with high voltages, the gel deforms towards the anode. A recent application into electrohydraulic actuators requires PVC gels to be analyzed in tensile testing modes driving the need of elastic and hyperelastic constitutive relationships. A linear elastic region was found up to 25% strain and the elastic modulus and Poisson’s ratio were determined. Analyzing the PVC network was used to justify lower Poisson’s ratios as plasticizer content increased, suggesting the nature of the polymer network at low strains. Our work suggests PVC gels can be treated as isotropic and incompressible; however, higher plasticized gels tend to act less incompressible at small strains. A relationship between the elastic modulus and plasticizer weight ratio showed high agreement making it deterministic for any plasticizer content. Neo-Hookean, Mooney Rivlin, Yeoh, Gent, Odgen and extended tube constitute models are investigated. The Yeoh model shows the highest feasibility in electrohydraulic actuation and tensile modeling. Together, these findings establish a constitutive basis for PVC gels with DBA plasticizer, incorporating small strain elasticity, large strain nonlinear behavior, and network analysis while providing suggestive insight into the network structure required for accurately modeling the EPIC.