Influence of oligomeric resins on natural rubber-carbon black-silica composites for tire tread application

Abstract

The investigation aims to understand the impact of different resins on properties of natural rubber (NR) based tire tread composites, providing valuable insights for the optimization of tire performance. In current research six different types of resins, namely rosin modified dicyclopentadiene(DCPD), gum rosin, C5 aliphatic resin, alpha methyl styrene (AMS) resin, koresin and terpene phenol resin, were selected for assessing structural influence of resins on cure characteristics, reinforcement, abrasion resistance, cut-tear resistance, heat-build-up, viscoelastic properties of carbon black-silica loaded NR composites. During mixing of rubber composites, condensation reaction between hydroxyl groups of silica with phenolic groups of koresin and terpene phenol resin, leading to elimination of water molecules was confirmed by Fourier transform infrared spectroscopy. The addition of resins led to a reduction in crosslink density, maximum torque and delta torque. The compounds with gum rosin and rosin modified DCPD showed lower crosslink densities translating into lower tensile strength, lower stress at 100%, 200%, 300% strain, and higher elongation at break among the resins. Rosin modified DCPD based composite exhibited the highest cut growth resistance and tear strength. Rolling resistance indicator (tanδ@70 °C) of resin-based composites followed the order: gum rosin > rosin modified DCPD > koresin > C5 resin > terpene phenol resin > AMS resin. The snow traction (tanδ@-15 °C), the order was: AMS = C5 > gum rosin > terpene phenol = koresin > rosin modified DCPD. The dynamic stiffness (É) of the gum rosin-based compound was significantly increased at low strain (0.1%) and low temperatures (-80–20 °C) compared to other resins. Furthermore, atomic force microscopy was employed to analyze surface topography and roughness of the resin-based NR composites, providing valuable insights into interfacial characteristics.