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Published on September 1, 2002

A Comparison of Wet Grip Enhancing Polymers

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Date Published September 1, 2002
In Europe there has always been a strong emphasis on the wet traction performance of passenger car tires because of the prevailing weather conditions and also because of the demand for high performance tires. In North America wear and rolling resistance have traditionally been the main requirements but higher levels traction are now being demanded.
Wet grip represents one corner of the so called “magic triangle”, the others being rolling resistance and wear resistance. In general improvements in wet grip tend to be accompanied by increased rolling resistance and reduced wear resistance. Certain types of polymer such as high styrene E-SBR, and halobutyl rubber (CIIR or BIIR) have a significant effect on wet grip and have been used specifically as wet grip improvers in black filled tread compounds. Typically 5 - 20 phr of such polymers would be used, normally with some sacrifice in rolling resistance or wear resistance. More recently, polymers such as 3,4 polyisoprene (3,4 IR), nitrile rubber (NBR) and nitrile-styrene-butadiene rubber (NSBR) have been suggested as wet grip enhancing polymers. Most wet grip enhancing polymers are incompatible with tread elastomers such as SBR and BR and have relatively high glass transition temperatures.