Produção de borracha de estireno-butadieno por polimerização aniônica em solução com iniciadores bifuncionais

Abstract

The present work aimed at the synthesis of bifunctional initiators for production of SSBR rubbers (solution styrene-butadiene rubber) and the functionalization of these rubbers to improve the compatibilization with inorganic loads. The analysed initiators were based on n-BuLi (butyllithium) and diolefins DVB (divinylbenzene) or m-DIB (meta-diisopropenylbenzene), being synthesized and stored at different temperatures, polar modifier contents and solvents. The results showed that the best initiator was prepared with m-DIB at 40 °C, using the DTHFP (Ditetrahydrofurylpropane)/BuLi molar ratio of 0.1 in cyclohexane. Under these conditions, the produced initiator presented higher contents of multifunctional species and presented enhanced stability. The DTHFP/n-BuLi molar ratio of 0.1 was found to be the most appropriate because it allows for minimization of oligomer generation and for proper initiation of styrene polymerizations. In addition, addition of small amounts of the polar modifier contributed to the increase of the vinyl content in the SSBR microstructure and to randomization of the styrene fraction in the polymer chain. The formulations obtained produced compounds with dynamic-mechanical characteristics that were similar to the ones available commercially.