2S-Soy Protein-Based Biopolymer as a Non-Covalent Surfactant and Its Effects on Electrical Conduction and Dielectric Relaxation of Polymer Nanocomposites

2S-soy protein, a biopolymer extracted from soy protein isolate (2S-SPI), was studied as a non-covalent surfactant for polymer nanocomposites.This study showed that 2S-SPI effectively improved carbon nanofibers (CNFs) dispersion in poly(vinylidene fluoride).2S-SPI surfactant had remarkable impact on both electrical conduction and dielectric relaxation of the nanocomposites, particularly, at high temperatures.2S-SPI modified CNFs caused coupling of conductivity relaxation and structural relaxations of the nanocomposites, in contrast to pristine CNFs.Both Maxwell-Wagner-Sillars and conductivity relaxations were enhanced at high temperatures by 2S-SPI, which made different contributions to electrical conduction of the nanocomposites with or without surface modification.