Abstract

This study evaluated the effects of morphological differences in multiwalled carbon nanotubes (MWCNTs) on the mechanical properties, wear resistance, and cut-and-chip resistance of NR/SBR rubber compounds. Using NR/SBR as the base rubber, compounds with 5 phr MWCNTs of different morphologies were compared with a reference carbon-black formulation (Ref). The evaluation results demonstrated that the compounds formulated with MWCNTs exhibited improved damage resistance compared with the reference compound. In particular, for the C-1 compound formulated with long-fiber CNTs, the tear strength increased by approximately 12.3% (from 155 to 174 kgf/cm) and the mass loss in the cut-and-chip test decreased by approximately 12.0% (from 1.395 to 1.228 g). Furthermore, the DIN abrasion loss decreased by approximately 5.1% (from 138 to 131 mm³), indicating enhanced wear resistance. Meanwhile, the M100 value increased from 31 to 55 kgf/cm², confirming the excellent reinforcing effect of the CNTs. These results are attributed to the formation of an effective reinforcing network by the CNTs within the rubber matrix, which improves the stress-transfer efficiency and suppresses crack initiation and propagation. In particular, long-fiber CNTs exhibit superior crack resistance owing to their high aspect ratios, which providing a crack- bridging effect. This study confirmed that CNT morphology plays a critical role in the reinforcing efficiency and damage resistance of NR/SBR compounds. These findings are expected to serve as foundational data for extending the service life, reducing maintenance costs, and designing high-durability materials for various industrial rubber products.

Keywords: NR/SBR, MWCNT, Wear resistance, cut-and-chip, tear strength, crack propagation