Electromechanical-conductive natural rubber doped eggshell and eggshell membrane for drug delivery and actuator applications

Abstract

Natural rubber composite materials were prepared from vulcanization STR 5L in sulfur curing system by being added with eggshell and eggshell membrane in order to increase electrical and mechanical properties for biomimetic actuator and artificial muscle applications. Samples were vulcanized at temperature 150°C. Hen eggshells and eggshell membrane powder (0, 20, 40, and 60 phr) were added in natural rubber. The main composition of eggshells is calcium carbonate (CaCO₃) of high purity more than 96.35 wt% whereas the main composition of eggshell membrane is fibrous protein in terms of collagen. The best condition is addition of eggshell 40 phr (formula 3) and eggshell membrane 20 phr (formula 5) to obtain the highest storage modulus response equal to 2.85 x 10⁶ and 2.97 x10⁶ Pa, respectively. The curing time (Tc₉₀) of pure natural rubber (formula 1), formula 3, and formula 5 are 8.22, 6.73, and 5.67 min, respectively. Furthermore, the curing time, rheology, and electric field response of natural rubber composite materials are investigate by moving die rheometer and compression set, and the results are reported here.

Keywords: Composites; Eggshell; Eggshell membrane; Electroactive elastomer; Actuator