PAPER WITHDRAWN: Performance Hydrocarbon Resins in Passenger Car and Light Truck Tread Formulations: Properties and Compatibility Insights

Hydrocarbon resins (HCRs) are low molecular weight synthetic oligomers with relatively high glass transition temperatures.  Blending of certain HCRs into tire elastomers can increase the glass transition temperature, hence the growing industrial interest in utilizing HCRs to improve the wet traction properties of tire tread compounds.  An aromatic pure monomer resin (PMR) and an aliphatic C5 resin are contrasted in a high performance / summer passenger car radial (PCR) tread formulation at resin loadings in the range from 5 to 30 phr and in a light truck (LT) tread formulation at 7 phr of resin.  The PCR tread compound contains a miscible 70/30 blend of solution styrene-butadiene rubber (sSBR) and cis-1,4-polybutadiene whereas an immiscible 70/30 blend of natural rubber and sSBR is present in the LT compound.  In both formulations, the PMR provides significantly enhanced wet grip – rolling resistance balance and improved abrasion resistance compared to the C5 resin, based on viscoelastic predictors of tread performance and a laboratory Pico abrasion test.  These differences are discussed with regard to relative compatibility of the two resins with the elastomers in the formulations.