Tailoring the structural, electrical and thermal properties of zinc oxide reinforced chlorinated natural rubber/poly (indole) blend nanocomposites for flexible electrochemical devices

Elastomer nanocomposites based on chlorinated natural rubber/ polyindole (Cl-NR/PIN) blend with different loadings of zinc oxide (ZnO) nanoparticles were investigated with special attention to structural, morphological, thermal and electrical properties. The uniform dispersion of ZnO nanoparticles into the blend system has been successfully identified by the UV-Vis spectra. The chemical interaction of ZnO and Cl-NR/PIN blend was revealed by the appearance of an additional band in the 400-500 cm(-1) region in the FT-IR spectra of the blend composites. The improved crystallinity of the blend was evaluated with the XRD pattern of composites. The uniform dispersion of ZnO in the blend was identified with FE-SEM and HR-TEM images. TGA and DSC results showed that increasing the nanoparticle content increased the thermal stability and glass transition temperature of the blend nanocomposites. The dielectric constant of the blend composites was measured to detect fluctuations in electric dipoles caused by different polarisations. The AC electrical conductivity was enhanced by the addition of conducting metal oxide nanoparticles. The influence of temperature on the conductivity, activation energy and pre-exponential factor was evaluated with the universal power law and Arrhenius equation. The filler particles present in the composites form a continuous network of electrons and thereby facilitate smooth electrical conduction in the blended matrix. Maximum dielectric constant and AC conductivity was observed for composite with 5 wt.% filler loading considered as the threshold level where maximum interfacial contact was observed. The addition of ZnO increased the tensile strength, modulus and hardness of the blend nanocomposites while decreasing the elongation at break. Thus, these blend composites with high tensile strength, conductivity and dielectric behaviour can be used in the fabrication of flexible energy storage devices.