Enhanced electrical and dielectric properties of plasticized soy protein bioplastics through incorporation of nanosized carbon black

Abstract Conductive soy protein biocomposite plastics with high performance were fabricated with glycerol as plasticizer and nanosized carbon black (CB) as conductive filler. Adopting a pretreatment of the CB nanofiller, its dispersion, and interaction with matrix was improved. The results indicated the existence of strong hydrogen bonding between soy protein matrix and CB fillers, which improved the interfacial bonding. The strong interactions between CB and protein restricted the mobility of protein segments, resulting in a dramatical reinforcing effect for the CB filled composites and enhanced mechanical properties. Besides, the incorporation of CB into soy protein increased the thermal stability as well as the water resistance of the composites. Moreover, a low percolation threshold of 0.76 vol% and fine electrical conductivity were obtained for the bionanocomposites, resulting in improved electromagnetic interference shielding properties. This work provides a simple and green way for the preparation of conductive and electromagnetic interference shielding materials from natural polymers.