Tyre Asia February/March 2018 89
Reinforcing fillers
Fillers are a solid particulate material (inorganic or
organic) that has irregular, spherical, acicular, fibrous, or
platelet-like shape. The main role of addition of filler is
cost reduction and improvement in properties of a tyre
or other rubber products. Reinforcing fillers commonly
used for rubber typically have relatively large particle
sizes.
Such fillers are mostly inert without any major reactive
moieties on their surface. however, to improve the
surface hydrophobicity, electrical conductivity, thermal
conductivity and relative permeability of polymeric
materials, micro/nano-fillers are added.
In the recent past, many developments have taken
place in reinforcing-filler technology. They include the
introduction and usage of improved grades of highly
dispersible silica, developments of dual filler and nano-
filler for improved product performance. Introduction of
bio-fillers, polymeric fillers and ground rubber as a re-
cycling materials and eco-friendliness are also equally
important.
Major breakthroughs in reinforcing materials came
with the development of nano fillers. polymer
nano composites consisting of a very high degree
of reinforcement, high thermal stability, improved
impermeability of gases and good optical clarity. nano
composite will definitely change material demand
scenario to large extent in the days to come.
People are now focusing on the application of nano-
materials/ nano-composites for rubber and tyre
industries including the introduction and usage of
nano-silica, nano-zinc oxide, nano-carbon black, etc.
for performance improvement. There are several other
nano-particulate materials which are getting attention
from compounders such as nano-calcium carbonate,
nano-cellulose, nano-mica , nano-talc etc.
In recent years, there is a development of new nano-
particles from different polymers known as core–shell
nano-particles. These nano-particles have a crosslinked
core (e.g; neoprene) ; Fig. 3. Among nano-materials,
nano-clays are the most commonly used commercial
additive for the preparation of nano-composites,
accounting for nearly 80 % of the volume used.
carbon nano-fibres, carbon nano-tubes (mainly Multi
Walls carbon nano Tubes; MWcnT) ; Fig. 4 and
Polyhedral oligomeric Silsesquioxanes (PoSS); Fig.5
are also being used commercially in nano-composites.
however, the processing of nano-materials is a concern
due to their high aspect ratio and problems related to
the alignment of filler.
carbon black by plasma process replaces incomplete
combustion with direct splitting of the hydrocarbon
feedstock oil using plasma into hydrogen and carbon
black. It produces carbon black with predetermined
characteristics.nanostructure black is a family of new carbon blacks
characterized by rough surface and enhanced filler–polymer interaction ; Fig. 6. It hinders the slippage of
polymer molecule along the rough nanostructure surface
and reduces the hysteresis significantly.
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