ABSTRACT
As shown in Figure 3.1, certain properties will only either increase or decrease, for instance viscosity, hardness, but other ones will pass through extremes in the case of the reinforcing filler. This immediately suggests that there will be optimum loadings, for a given filler, in a given polymer, for a specific application. To establish the optimum filler level is therefore the most important task for the compounder, further complicated by the obvious requirement that the compound must remain processible at reasonable
energy and labor costs; sometimes the excessive viscosity increase imparted by very active fillers, either limits their practical level in certain elastomers or requires additional modification in formulation, for instance higher levels of processing oils, or plasticizers, which generally have a penalizing effects on certain mechanical properties of the vulcanized part.
