Each neat rubber or plastic has specific properties that can be modified and enhanced by additives. Carbon blacks are the most popular reinforcing agents for rubbers, particularly for tyres. Silicas, which are in competition with carbon blacks, have one significant advantage them: their white color.
The most important role of silicas is:
* Elastomer reinforcement inducing an increase in the mechanical properties.
But they are also used in rubbers and plastics:
* To promote adhesion of rubber to brass-coated wires and textiles. They are used alone or as part of a HRH system.
* As antiblocks for plastic films.
* To enhance the thermal and electrical properties of plastics.
* In accumulator separators.
* As rubber chemical carriers.
Like carbon blacks, silicas are also cost cutters:
* By decreasing the rubber weight (and its cost) whilst retaining the same mechanical performances.
* By enhancing functional performances such as abrasion resistance.
This paper concerns rubber reinforcement with fumed silicas and precipitated hydrated silicas.