Toward Biosourced Elastomer from β-Farnesene and Styrene: Synthesis, Properties, and Mechanical Performance

Abstract

Encouraged by the growing need for sustainability in the rubber industry, attempts have been made to fabricate biobased elastomers to replace existing petro-derived polymers for useful applications. Here, we demonstrate a simple and sustainable route to synthesize biobased elastomers based on β-farnesene (FA) and styrene (STY) under a high-temperature persulfate emulsion process for tire applications. The synthesized copolymer, poly(farnesene-co-styrene) (PFS), showed molecular weight (Mw) of 108 500 g/mol and 162 100 g/mol for 30 and 50 wt % styrene contents. The commoner reactivity ratios showed nonideal copolymerization behavior, as evaluated using Fineman–Ross and Kelen-Tüdös methods. The macromolecular chemical structure of PFS elastomers was confirmed by FT-IR and NMR analyses. The copolymer showed complete 1,4-cis and trans-microstructure formation. The glass-transition temperature (Tg) values of PFS elastomers were obtained in the range of −58 and −38 °C, depending on the styrene content. The PFS gum elastomers displayed improved thermal stability and single degradation pattern compared to the pristine polyfarnesene. Besides, carbon black was incorporated into the PFS elastomer matrix to prepare rubber vulcanizates for desired mechanical properties. The 50/50 FA/STY rubber vulcanizates displayed good tensile strength (4.43 MPa), elongation at break (183%). The 80/20 and 70/30 FA/STY rubber vulcanizates exhibited good wet skid resistance compared to its pristine polyfarnesene vulcanizate. This work provides an efficient approach to using emulsion polymerization for developing sustainable rubbers on an industrial scale for multifaceted applications.