Stubble resistance of rubber vulcanizates: Influence of short fiber and resin

Abstract

Stubble resistance of tread rubber vulcanizate of a tyre is crucial, especially for the off-the road (OTR) tyres. However, it has not been vividly discussed in the literature. Here, we developed a test method for stubble resistance, and studied the effect of short aramid fibre and two different types of resins on the stubble resistance of a conventional tire tread recipe with a view to its improvement. Resin filled compositions, being flexible, showed better cut initiation resistance, as compared to aramid fibre filled stiffer compositions, by dissipating the stress through chain orientation. During penetration, both cut growth and frictional force were important. For the aramid fibre composition, the frictional force dominated, whereas the cut growth was predominant for the resin filled vulcanizates. How the different energies associated with the fracture, e.g. cut initiation and growth energies, frictional energy and total fracture energy, altered with respect to the modulus or elongation at break of the rubber vulcanizates has also been discussed. At 4–6 phr of aramid filler concentration, stubble resistance drastically improved. On the other hand, the resin at 4 phr concentration exhibited an overall improvement in stubble resistance as compared to the conventional recipe. In summary, the present work contributed to the effect of different parameters on the stubble resistance of a tire tread rubber vulcanizate using an inhouse developed new test method.