Studies on the use of nano zinc oxide and modified silica in NR, CR ...

Chapter 1
not contribute to the elastic behaviour of the matrix, as their properties
resemble the properties of the rigid filler particles rather than the properties
of the elastic and flexible free polymer chains. Occluded rubber increases the
effective filler loading and thus the strain independent contribution to the
modulus. The filler-polymer interaction can be attributed to physical
interactions, for example Van der Waals forces, or chemical reactions as in the
case of a silica-coupling agent system. 74-76
1.4.3 Mesoporous silica
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Precipitated silica particles have been utilized successfully as rubber
reinforcing fillers instead of carbon black. 77-81 The development of new
mesoporous silica particles with properties different than that of the
precipitated silica particles, specially their high BET surface area and their
organized pore structures with pore sizes between 1.5-10 nm, make them
potential materials in rubber reinforcing. It is well known that mesoporous
silica materials are synthesized by synergistic self assembly between
surfactant and silica species to form mesoscopically ordered composites. 82-83
Generally two types of surfactants are used for the formation of mesoporous
silica materials. Ionic surfactants such as alkyltrimethylammonium bromide 84
and nonionic surfactants such as alkylamine 85 and poly(ethylene oxide) -type
copolymers. 86 The ionic surfactants interact electrostatically with inorganic
species, whereas the nonionic surfactants result in the formation of
mesocomposites through hydrogen bond or Van der Waals interaction. The
nonionic surfactants give commercially important advantages compared with
the ionic surfactants. They are easily removable, non-toxic, biodegradable and
relatively inexpensive. Pinnavaia et al. 87 have reported the synthesis of
MSU-X mesoporous materials with several nonionic surfactants. These
materials are composed of worm-like channels, which are disorderedly
arrayed. Stucky et al. 88 have reported the synthesis of SBA mesoporous silica
materials, which have well-ordered channel and cage structures, using