Improved off-the-road tire formulations with discrete surface functionalized multiwall carbon nanotubes: Correlating wear,abrasion and tear resistance with cut and chip to predict lifetime

摘要

The off-the-road(OTR)tread is a mixture of crosslinked elastomers with filler network,as well as a reinforcing filler-elastomer network.Typically,carbon black(CB)(refs.1 and 2)is used in tire formulations for reinforcing the elastomer matrix.Silica(refs.3 and 4)with some combinations of silane coupling agents is used to enhance the wear and abrasion properties.However,the amount of fillers,as well as the coupling agents,while improving the properties,frequently hamper the process-ability of the compound.Since the discovery of carbon nanotubes in 1991(ref.5),many research groups have employed single-(SWCNT),double-(DWCNT)and multi-wall(MW-CNTs)in various polymers and elastomers to achieve improvements in the mechanical properties based on theoretical calculations(refs.6-9).However,due to their existence as bundles and the poor dispersion quality in the final matrix,the resultant properties are not as high as expected.The true potential of enhanced mechanical properties of elastomer composites with multiwall carbon nanotubes(MWCNTs)can be achieved when they are completely disentangled and dispersed in the host matrix.Molecular Rebar(MR)is completely disen-tangled,discrete,cleaned of catalyst residues and surface functionalized multiwall carbon nano-tubes.The presence of surface functionalization facilitates good bonding between the rubber ma-trix and tube surface for improved load transfer,which results in higher tear and tensile properties,as well as enhancements in wear and tear resis-tance.In this article,we discuss the delivery of MR via elastomeric specific masterbatches,as well as via a naphthenic oil based dry liquid con-centrate(DC)into an OTR formulation,and the resulting improved tear,wear and abrasion proper-ties are evaluated.