Filler Reinforcement in Silicone Polymers. Part I. The Effect of Finely Divided Materials on Liquid Polymers

摘要

The effect of finely divided materials on a polydimethyl silicone oil was studied in the temperature range from 30 to 130C using a variable shear viscometer. The results are consistent with the view that fine powders become solvated on being dispersed in the oil; if a sufficient number of particles are present per unit volume of mixture and if the interactions between them are sufficiently large, aggregation can occur to give a micro-gel structure. Those materials which are highly reinforcing in silicone elastomers show evidence of micro-gel structure at volume concentrations below 4 per cent. For fillers of a given chemical type there are indications that the visxcosity increment is dependent solely on mean particle size: there are further indications that carbon black is more effective in raising the viscosity than silica providing they are of comparable particle sizes. (Author)