Silica-Reinforced Natural Rubber with Epoxidized Low Molecular Weight Rubber as a Compatibilizer

Abstract

This work investigates the effect of epoxidized low molecular weight natural rubber (ELMWNR) in silica-filled NR compounds on processing, mechanical and dynamic mechanical properties. The ELMWNRs with mol% epoxide groups varying from 0-50 and molecular weight in a range of 50,000-60,000 g/mol were prepared from depolymerization of epoxidized natural rubber using periodic acid in latex state. They were then added in the silica-filled NR compounds as a compatibilizer at varying loading from 0-15 phr. The addition of ELMWNR decreases compound viscosity and Payne effect, i.e. filler-filler interaction. The optimal mechanical properties of silica-filled vulcanizates are observed at the ELMWNR-28 (28 mol% epoxide) loading of 10 phr. The incorporation of ELMWNR with 28 and 51 mol% epoxide groups into NR compounds introduces a second glass transition temperature and affects on their dynamic mechanical properties. Higher epoxide content leads to higher Tan δ of the rubber vulcanizates in the range of normal service temperature.

Natural rubber‐graft‐poly(2‐hydroxyethyl acrylate) on cure characteristics and mechanical properties of silica‐filled natural rubber composites

“…The reinforcement index was calculated by dividing the modulus at 300% elongation by the modulus at 100% elongation. It is used to assess rubber–filler interactions . It was found that the reinforcement index of NR/silica composites significantly increased with grafting level in NR‐g‐PHEA, corroborating stronger rubber–silica interactions seen also in the bound rubber content in Figure , and causing a higher resistance to deformation.…”

Property Enhancement of Silica-Filled Natural Rubber Compatibilized with Epoxidized Low Molecular Weight Rubber by Extra Sulfur

“…Another more environmental friendly alternative is epoxidized natural rubber (ENR) which has been used both as compatibilizer [4] and as matrix [5] for silica-filled rubber compounds. Epoxidized low molecular weight natural rubber (ELMWNR) has been used as a compatibilizer to enhance processing and mechanical properties of silica-filled NR [6], but the properties are still inferior compared to the TESPT/silica system. As TESPT also plays a role as sulfur donor during mixing and vulcanization, and positively affects on the properties of silica/silane-filled NR [1], this present work investigates an influenece of extra sulfur added to the silica-filled NR compounds which are compatibilized with ELMWNRs.…”