Effect of silane coupling agent and cellulose nanocrystals loading on the properties of acrylonitrile butadiene rubber/natural rubber nanocomposites

Abstract

In this study, the effects of cellulose nanocrystal (CNCs) loading and the silane coupling agent (3-triethoxysilylpropyl) tetrasulfide (Si-69) on the properties of a nanocomposite composed of acrylonitrile butadiene rubber (NBR) and natural rubber (NR) at a 50/50 ratio were explored. CNCs were extracted from Luffa cylindrica and incorporated into NBR/NR nanocomposites at a level of 0–5 parts per hundred rubber (phr). Incorporation of CNCs exhibited safe cure and good processability of rubber nanocomposites. The presence of Si-69 in the NBR/NR nanocomposites improved the interaction between CNCs and the polymer matrix, resulting in improved mechanical properties such as hardness, abrasion resistance, tensile strength, and elongation at break compared to those not containing silane. The rubber nanocomposite with silane demonstrated better thermal aging properties than rubber nanocomposite without silane at any given filler loading. The optimal level of CNCs filled in rubber nanocomposite containing Si-69 was 1 phr, which was further validated by examining its dynamic mechanical characteristics and phase morphology. Mechanical characteristics were poor at high levels of CNCs (greater than 1 phr) due to phase separation and filler agglomeration in the rubber nanocomposites. Furthermore, incorporation of 1 phr CNCs in rubber nanocomposites with silane improved ozone aging and thermal stability of the rubber nanocomposites.