Modification of Rubber Compounds Based on Isoprene Rubber Using Synthetic Diopside

Abstract

To replace white carbon black in rubber formulations with more economical and less toxic mineral fillers, one can use diopside, as containing a large amount (51–53 wt. %) of silicon dioxide, and previously successfully used for filling epoxy and polyester materials.
It has been established that replacing 20 parts by weight of white carbon black with diopside decreases the Mooney viscosity of model rubber compounds based on SKI-3 and increases their resistance to premature vulcanization, thereby facilitating processability. An optimal diopside content of 20‒30 parts by weight per 100 parts by weight of rubber maintains hardness and increases strength and tensile elongation by 30 and 14 %, respectively, as well as increases rebound elasticity approximately by 1,5 times. The tear resistance of rubber compounds with the addition of diopside, depending on its dosage, decreases by 12 to 19% compared to the reference standard. This may be due to the fact that diopside has lower porosity and particle size compared to white carbon black, which reduces its activity as a filler. The data obtained allow us to recommend the use of diopside as a partial (20‒30 parts by weight per 100 parts by weight of isoprene rubber) replacement for white carbon black in the production of rubber products that are not subject to increased shear deformation or rupture during use.