Use of fly ash as eco-friendly filler in synthetic rubber for tire applications

Abstract

A byproduct of the power generation industries, fly ash can be used as a potential filler in many commercial products including rubber-based products. Reusing the fly ash in this manner is an efficient way to help prevent air pollution which occurs if such particles are released freely to the atmosphere. The reinforcement efficiency of fly ash for partial replacement of carbon black and silica fillers in styrene-butadiene rubber compounds was investigated in this work. The total content of fillers was held constant at 50 phr (weight ratio of filler to rubber was 0.5) when not using silica fillers at all, and 54 phr when using 4 phr carbon black only with silica fillers, while the content of fly ash increased from 0 to 10 phr. In the evaluation of the rubber compounds, the focus was the mechanical properties and adhesion of steel reinforcement cords to the styrene-butadiene rubber compounds. Adhesion between the compounds and steel wire reinforcement was measured for assessing efficacy of adding fly ash to the rubber compounds in tire applications. Ball mill treatment was used to reduce the size of the fly ash particles while also modifying their surface topography. The comparisons of untreated and ball mill treated fly ash filled rubber compounds and rubber compounds containing different fillers were accomplished subsequently. The results revealed that the partial addition of up to 10 phr fly ash to rubber compounds resulted in increases in elongation at break, adhesion to reinforcement steel cord, wet-grip, as well as lower rolling resistance as attributed to more effective filler dispersion and the reinforcing effect of silica present in fly ash.