Study of the Reinforcing Effect of Modified Kaolin in Elastomeric Materials Based on Nitrile Butadiene Rubber

Abstract

Modification of kaolin with aqueous solutions of sodium hydroxide was carried out. The influence of the ratio of the initial kaolin and alkali on the chemical composition of the resulting filler, its specific surface area, degree of crystallinity and average crystallite size was studied. It has been shown that modification of kaolin makes it possible to increase the content of the number of reactive hydroxyl groups by 2–3 times. To study the structure and properties of fillers, IR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET methods were used. The influence of the composition and properties of modified kaolin on the properties of rubber compounds based on nitrile butadiene rubber and the main physical and mechanical characteristics of their vulcanizates was studied. It has been shown that an increase in the content of hydroxyl groups in the filler leads to an increase in the number of interfacial chemical bonds between the filler and the elastomeric matrix, which increases the tensile strength of vulcanizates by 1,5–1,8 times, while maintaining a high level of elasticity. The kinetics of rubber compound vulcanization and the Payne effect were studied using the MonTech Dynamic Rubber Process Analyzer D-RPA 3000 instrument. The degree of cross-linking of the vulcanizates was evaluated based on the equilibrium swelling of the rubbers in toluene. The physical and mechanical testing of the vulcanizates was performed using the AI-3000 Gotech universal testing machine.