Effect of Fly Ash as Filler in Rubber – A Comprehensive Study of the Vulcanisate Properties of Styrene-Butadiene Rubber Compounds

Abstract

The effect of fly ash as a filler for an ESBR-based compound was studied in the range 0-80 phr. Characterization of fly ash, as received, revealed the abundance of 200 mesh size particles with an average diameter of 10 μm; composition analysis showed the predominance of silica and alumina. The properties of ESBR compounds filled with fly ash particles of ≤200 mesh were compared with those of clay- and whiting-filled compounds. The cure rate index remained unchanged for fly ash throughout the range of loading studied here; clay showed a lower cure rate, and whiting showed a higher value than fly ash. The 300% modulus values did not show any improvement with increase in fly ash loading, the values being comparable with those for whiting and inferior to those for clay. Fly ash gives the lowest heat build-up and tan delta (at 70°C) values among the three fillers under discussion.