Journal of Applied Polymer Science, Vol.69, No.1, 95-107, 1998
Experimental testing of the polymer-filler gel formation theory. II.
In Part I of the present article predictions of the polymer-filler gel formation theory were tested experimentally using fine-particle silica in natural rubber (NR) and in styrene-butadiene rubber (SBR). Part II brings a more detailed experiment theory comparison using carbon blacks differing in specific surface area and structure, graphitized blacks, fume silica, and surface-modified (hydrophobized) fume silica. In the region of low and medium filler concentration c, the c-dependence of the fraction G of polymer in polymer-filler gel, of the fraction B of total filler-bound polymer, of the fraction w(disp) of solvent-dispersed filler particles were found to be correctly predicted by the theory. The effect of filler characteristics and of the method of its incorporation into the polymer on the values of the adjustable parameters of the theory (filler surface adsorptivity, D, and filler particles connectivity, f) was determined and is discussed. In the region of very high c increasing positive deviations of D from the low-c behavior were observed and an explanation for this effect is proposed.
Keywords:BOUND RUBBER