Effect of Organomodified Bentonite/Silica Hybrid Filler Compound System on Mechanical Properties and Sealing Performance of NR/NBR Rubber Seal for LPG Tube Valve

Abstract

Organomodified bentonite and silica were used as hybrid fillers in natural rubber (NR)/nitrile butadiene rubber (NBR) seal for liquified petroleum gas (LPG) tube valve compound to evaluate their interaction and influence on mechanical properties and sealing performance. In this work, the NR-organomodified bentonite were prepared by the in situ organomodified and latex compounding method with varying amounts of bentonite then applied in the silica-NR/NBR rubber seal compounds with mixing process held in two rolls open mill. Silanization reaction, Payne effect, curing characteristics, tensile properties, compression set, hardness, uniaxial compression and sealing performance were assessed. The study obtained that NR/NBR-silica/organomodified bentonite show improved silica dispersion physically, as analyzed by Payne effect. The presence of organomodified bentonite decreases the vulcanization reaction. The cure rate index, apparent crosslink density and hardness tend to decrease with addition of organomodified bentonite, while tensile strength and elongation at break are enhanced with increasing organomodified bentonite. With an appropriate amount of organomodified bentonite (organomodified bentonite below 4 phr), the introduction of organomodified bentonite enhances the elastic response of the material, as shown by increasing of tensile properties. The rubber seal’s sealing performance analysis revealed that B4 (4 phr organomodified bentonite) performed the best, with contact stress higher than the actual working pressure and Misses stress lower than the actual working pressure, making it difficult to crack.