The Role of Functional Polymers in Improving Tire Performance

Alkoxysilane functionalized poly(butadiene-co-styrene) elastomers were prepared by terminating the anionic polymerization with tetraethylorthosilicate (TEOS).  The isolated product contained 60-70% coupled polymer.  A facile method for characterizing the type of coupling was developed using tetrabutylammonium fluoride as the decoupling agent.  Analysis showed  >95% of the coupled product was from condensation of the alkoxysilane endgroups during workup and only 3% was due to two polymeric lithium chains reacting with one TEOS molecule.  The alkoxysilane functionalized elastomers continued to increase in viscosity with storage.  Neutralization of the polymer solution with 2-ethylhexanoic acid or addition of sterically hindered alcohols was able to reduce the coupling and viscosity increase.  The alkoxysilane functionalized polymer improved hysteresis and wear compared to a similar non-functional polymer in silica containing tire tread applications.