In Situ Synthesis of Rubber Nanocomposites

The preparation and characterization of rubber based nanocomposites prepared by in situ generation of inorganic oxides by means of the hydrolytic sol– gel process are reviewed in the present chapter. The sol–gel approach has been applied to several rubber matrices to prepare reinforced vulcanized and unvul- canized rubbers. Several synthetic procedures are presented while the most investigated filler is silica obtained by hydrolysis and condensation of tetraeth- oxysilane. The effects of the different preparation conditions and of the filler content are generally discussed in terms of morphology (investigated by electron microscopy and small angle X-ray scattering) and mechanical properties (modulus, strength and extensibility). The mechanical properties of the in situ filled nano- composites are generally better than those of the corresponding materials prepared with the conventional mechanical mixing of preformed particulates and elasto- mers. This enhancement is generally attributed to a lower tendency to filler–filler aggregation due to a lower particle surface interaction resulting from the ‘bottom- up approach’ of the sol–gel process applied to the preparation of organic–inorganic hybrid materials.