Improving the curing performance of styrene-butadiene rubber/butadiene rubber composites through the addition of silicon nitride

The objective of this research was to investigate the impact of silicon nitride (Si₃N₄) on the compression moulding process of potential passenger tyre tread compounds, which include both butadiene rubber (BR) and styrene-butadiene rubber (SBR). Understanding how Si₃N₄ influences the curing process, particularly through temperature monitoring in the mould, is crucial for optimising the vulcanisation and performance characteristics of tyre tread compounds. By examining the kinetic reaction characteristics and thermal properties, this study aims to elucidate the role of Si₃N₄ in enhancing the efficiency and effectiveness of the curing process. The obtained kinetic reaction characteristics demonstrated a decrease in the duration of optimum curing and scorch by ~ 25 and ~ 40%, respectively, by adding silicon nitride. Moreover, the rheometry analysis illustrated an increase of ~ 12% in maximum torque when 6 phr of Si₃N₄ was loaded. The Kamal–Sourour model, employed for the determination of kinetic parameters, revealed that the thermal conductivity of Si₃N₄ played a catalytic role in enhancing the curing reaction by approximately 40%, notably at 6 phr of filler. Temperature monitoring results revealed that the Si₃N₄ particles increase the heat transfer rate and thermal diffusivity by approximately 17 and 98%, respectively, during curing. This increase is also observed in the cured compound, with a notable improvement of around 17%, particularly at 6 phr of Si₃N₄. This phenomenon facilitated a uniform heat distribution within the sample during the moulding process, resulting in an accelerated vulcanisation reaction.