Use of bagasse fiber ash as secondary filler in silica or carbon black filled natural rubber compound

This work studies possibilities of using bagasse fiber ash (BFA) as alternative and/or secondary filler in natural rubber (NR) compounds containing either precipitated silica (PSi) or carbon black (CB) as the primary filler. The effects of the filler content and weight fraction ratio of BFA in PSi and CB fillers on cure characteristics, and mechanical properties were of interest. The studies reveal that silicon dioxide (SiO2) was the major component of BFA with 75.4% by weight and the rest was metal oxides. The BFA particles showed porosities and shape irregularities with a particle size range of 45–150 μm. For the neat filler system, it was found that the BFA filler could be used potentially as alternative filler in NR compounds with a recommended loading of not greater than 15 parts per hundred rubber. Lower tensile strength of the vulcanizate with BFA filler, as compared to PSi and CB filler, was due to the poor dispersion level and an aggregation of the silica particles in the rubber matrix. In the hybrid filler system, BFA could be used to replace both PSi or CB filler up to 75% of the total hybrid filler (either BFA:PSi or BFA:CB) not exceeding 15 phr, without affecting the ultimate mechanical properties. The results of ultimate mechanical strength and swelling measurements clearly indicated that the BFA filler had more compatibility for addition with PSi filler than CB.

► Bagasse fiber ash could be used as secondary filler in natural rubber compounds.
► SiO2 was the major component of bagasse fiber ash with 75.4% by weight.
► Bagasse fiber ash had more compatibility for addition with PSi filler than CB.