Rice husk silica is being recently used in rubber product as a filler but it is not able to give properties which can be obtained by using standard silica like vn3 and hydrated one. Kindly inform me which properties of rice husk silica make it lags from vn3
This is my perspective from the field of cement and concrete. Rice husk ash and silica fume are both used as additions to concrete. As with what you have said, while both have an effect, RHA is not as effective.
The main differences are in the elemental composition and the particle morphology. RHA is more angular and likely coarser than silica. In terms of composition, silica will be almost pure while RHA will contain impurities. The silica content of RHA can range from ~70 to 90%, with traces of CaO, Al2O3, Fe2O3 and alkalis. You are also likely to have a loss on ignition with RHA from 2-5% (with the higher value coming from low-technology burning).
Hopefully this is of use to you.
Regards,
Leon
The particle size of rice husk silica is higher than VN3. Particle size of VN3 varies from 150 to 220 nm and rice husk silica range from 0.030 to 100 μm. The reinforcement and mechnical properies higer for lower particle size fillers. I request you to refer the specifications of both silica and polymer filler intraction.
The basic differences between rice husk ash(RHA)and commercial silica (CS)are their surface area, particle size and purity of silica.
RHA surface area-less than 15 m2/g, particle size greater than 100 nm.
Rice husk ash can provide better cure rate index CRI than CS filled vulcanizates.
Modulus, hardness comparable
Other mechanical and technological properties will be inferior.
RHA generally have low purity and more amorphous comparing to commercial silica. However we can purify them. By using sintering, we can change the RHA characteristics to desired properties
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