Rice husk ash, used as received (RHA) or milled (MHA), was investigated in
natural rubber (NR) for its potential as a new type of filler. The physical
testing of the NR vulcanizates involved tensile, tear, and abrasion resist
ance, hardness and resilience. The interaction between rice husk ash and na
tural rubber was investigated by swelling in an organic solvent. The effect
of the coupling agent, bis(3-triethoxy-silylpropyl)-tetrasulfane (Si-69),
on the curing and physical properties of the vulcanizates was investigated.
The presence of the silane coupling agent has not brought the expected inc
rease in properties, yet MHA exhibits the best overall vulcanizates propert
ies when compared to RHA, although still inferior to commercial fillers as
precipitated silica (Zeosil-175) and carbon black (N762), especially with r
egard to tensile strength and abrasion resistance.