Effect of Swelling on Electrical Properties of Rubber Composites: Potential Materials for Liquid Detections

Rubber matrix was controlled to be hydrophilic, swellable, and conductive, by mixing with varied amounts of epichlorohydrin rubber (GECO), polyethylene oxide (PEO), and ethylene–vinyl acetate (EVA) polymers, et cetera. Higher concentration of the epichlorohydrin rubber (GECO) resulted in higher curing times ( t s2 and t 90 ), high torque values ( M L , M H , and ∆ M ), high crosslinking density, and higher stiffness (MPa). Sample GP1 recorded highest strength due to the high content (70 part per hundred of rubber [phr]) of the epichlorohydrin rubber (GECO). All the compositions exhibited wetting and hydrophilic behavior, with contact angle V / V o ), the gauge factor (GF = [∆ R / R o /( V / V o ]) deduced for the compounds was within approximately 1.3 × 10 3 –9.6 x 10 3 , which is the first to be reported for liquids (petrol, diesel, kerosene, cooking oil, and water), to the best of our knowledge. These GF values were higher and comparable to many other strain gauges made of rubber‐reinforced/coated with graphene, and carbon nanotubes (CNTs), et cetera. Thus, the current compositions exhibit multifunctional capabilities for liquid/chemical sensing, soft robotics, agro‐mulching, and real‐time soil moisture monitoring applications.