ABSTRACT
In contrast with carbon black, silica has particular surface properties that bring a number of problems when using such materials as reinforcing fillers, particularly in hydrocarbon elastomers. Indeed the surface of silica, either fumed or precipitated, is strongly polar and hydrophilic, owing to its polysiloxane structure with numerous silanol groups. This particular surface chemistry of silica has several immediate consequences:
1. Silica surface can adsorb significant quantities of water, as reflected by the well known usage of the material as drying agent (or moisture absorber)
2. Moist silica is very difficult to dry 3. Interparticle interactions are very strong because of hydrogen
bonding 4. Silica is the ideal filler for silicone polymers, for instance
polydimethylsiloxane 5. When used as filler for diene elastomers, chemical modification
of silica surface is required firstly to promote mixing through decreased inter-particles interactions and secondly to establish adequate rubber-filler interactions.
