Effect of sol–gel modified nano calcium carbonate (CaCO3) on the cure, mechanical and thermal properties of acrylonitrile butadiene rubber (NBR) nanocomposites

Abstract

The main goal of this work is to modify surface of nano CaCO3 with silica by an elegant approach of sol–gel method and also to compare the influence of sol–gel modified nano CaCO3 with unmodified nano CaCO3 in the cure, mechanical and thermal properties of acrylonitrile butadiene rubber (NBR) nanocomposites. The surface modification of nano CaCO3 is characterized by Fourier transform infrared spectra and Field emission scanning electron microscopy. The modified nano CaCO3 causes significant improvement in the maximum rheometric torque (R∞) and cure rate index value of NBR nanocomposites in comparison to unmodified nano CaCO3. More importantly, incorporation of surface modified nano CaCO3 provides substantial enhancement in the mechanical properties of NBR nanocomposites and at 4 phr (parts per hundred parts of rubber) filler loading level tensile strength of modified nano CaCO3 filled NBR vulcanizate shows a large increment by 37.33 % compare to that of unmodified nano CaCO3 filled NBR vulcanizate. Thermogravimetric analysis reveals that sol–gel modified nano CaCO3 delivers greater thermal stability in NBR nanocomposites than unmodified nano CaCO3. The fantastic enrichment in the cure, mechanical and thermal properties of NBR nanocomposites containing surface modified nano CaCO3 will be the part of great interest for rubber researcher regarding the broad application of sol–gel modified nano CaCO3 as important filler in rubber industry.