Evaluation of cure characteristic, physico-mechanical, and dielectric properties of calcium copper titanate filled acrylonitrile-butadiene rubber composites: Effect of calcium copper titanate loading

Calcium copper titanate (CCTO) has been synthesized by high temperature solid-state reaction from calcium carbonate, copper (II) oxide, and titanium dioxide as the starting materials. The formation and morphology of CCTO were confirmed by X-ray diffraction, Fourier-transformed infrared spectrophotometry, scanning electron microscopy (SEM), and particle size analysis. In order to develop flexible dielectric materials, acrylonitrile-butadiene rubber (NBR)-based composites were prepared with CCTO content varied from 0 to 120 phr (parts per hundred rubber). The cure characteristics of composites were assessed. High-dielectric constant CCTO particles were blended into NBR to make composites with improved dielectric constant. Results showed that the NBR/CCTO composites had a high dielectric constant (10-20) with low dielectric loss (<0.4) and low conductivity (<10(-3) mu S/cm) at frequencies up to 10(6) Hz. However, the higher CCTO loadings had agglomeration in the NBR matrix, and thus tensile strength and elongation at break sharply deteriorated due to poor rubber-filler interactions. The results showed lower storage modulus E ' and a reduction in T-g with the incorporation of CCTO in NBR matrix. Moreover, improved thermal stability of the NBR/CCTO composites was achieved. SEM was used to observe the dispersion of CCTO particles in NBR matrix.