Effectiveness of four new silane coupling agents in solution styrene butadiene rubber–based silica tire tread compounds were evaluated with respect to two commercial silane coupling agents. The new silane coupling agents investigated were 1-[3-(octanoylthio) propyl]-1,1,3,3,3-pentaethoxy-1,3-disilapropane (S1), bis[3-(octanoylthio)-1-propyl]-diethoxysilane (S2), 5-(triethoxysilylpropylthia)-2-potassium-1,3,4-thiadiazolate (S3) and 2,5-(triethoxysilylpropylthia)-1,3,4-thiadiazole (S4), and the two commercial silanes used for the comparison were bis(triethoxysilylpropyl) tetrasulphide (Si69) and 3-octanoylthio-1-propyltriethoxysilane (NXT). The chemical structure of S1 and S2 silanes was based on the NXT silane. S3 is a monofunctional silane, whereas S4 is a bifunctional silane based on the chemical structure of S3. The effectiveness of the coupling agents were found to be varying for different properties of the rubber compounds. The S3 and S4 silane compounds were having shorter cure time and higher maximum torque values compared with other compounds; however, the tensile strength and the tanδ values indicative of tire performance were lower than that of the other silane compounds. The NXT, S1 and S2 silane compounds showed higher tanδ at 0°C and lower tanδ at 60°C, compared with the other compounds, indicative of improved wet skid resistance and lowered rolling resistance of these compounds. The Si69 compound showed higher tensile properties and lower abrasion when compared with the other compounds; however, the tanδ values for the tire performance were slightly lower to the NXT, S1 and S2 silane compounds.

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 (M w ) 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-Tudos methods. The macromolecular chemical structure of PFS elastomers was confirmed by FT-IR and NMR analyses. The copolymer showed complete 1,4-cis and transmicrostructure formation. The glass-transition temperature (T g ) 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.

Synthesis of 6-Hydroxyalkylidenepenicillanates.-6-Hydroxyalkylidenepenicillanates such as (VI) are synthesized from dibromopenicillanate (I) via a sequence of reactions involving condensation with appropriate chiral aldehydes, subsequent reduction and Mitsunobu elimination.