Synthesis and evaluation of new antioxidants for styrene butadiene rubber

Purpose - The purpose of this paper is to study the effect of new heterocyclic compounds on styrene butadiene rubber (SBR) mixes. Design/methodology/approach - It has been found that the starting material 1 could react with cyromazine (2) and/or 4-aminoantipyriene (4) as amino compounds in the presence of triethylorthoformate and in the boiling dioxane to yield triazine-3 and/or pyrazolo 5 derivatives, respectively. The chemical structures of the new products 3 and 5 have been established by their elemental analyses spectroscopic data IR, Ms and 1H, 13C NMR. These two compounds were evaluated as antioxidants in SBR, and this evaluation was confirmed by physico-mechanical properties of vulcanizates, IR spectra and scanning electron microscope. Findings - The difference between maximum torque MH and minimum torque ML (Delta M), tensile strength, modulus and elongation at break increases in the presence of prepared antioxidants while the equilibrium swelling decreased. The rubber vulcanizates were subjected to thermal oxidative aging at 90 degrees C for up to seven days. It has been found that new compounds 3 and 5 can protect SBR vulcanizates against oxidative deterioration. Research limitations/implications - The solubility of the prepared compounds 3 and 5 is very poor and they are only soluble in dimethyl formamide (DMF) or dimethyl sulphoxide (DMSO) which have high boiling points. Also, new compounds 3 and 5 have melting points (above 300 degrees C). Practical implications - Triazine and antipyrine derivatives have many medical and industrial applications. Originality/value - The new synthesized compounds revealed excellent antioxidant behaviour in comparison with the commercial antioxidant phenyl-beta-naphthyl amine (P beta N) which is used in industry.