MELT RHEOLOGY OF IONOMER FILLED WITH METHYL METHACRYLATE-GRAFTED PERLITE

The shear viscosity, the shear compliance, and their shear rate dependence were determined by a Weissenberg rheogoniometer, and the effect of the grafted poly(methyl methacrylate) chains on the intensification of the interaction at the interface between the ionomer matrix and the filler was discussed. Results were as follows: (1) The relative viscosity of the ionomer filled with MMA‐grafted perlite to the matrix ionomer and the yield stress increased with increase in the volume fraction of perlite, and these behaviors were more remarkable in the case of the perlite with larger quantity of grafted PMMA. (2) The effective thickness of the immobilized matrix layer on the filler surface in the Ziegel equation and the crowding factor in the Mooney equation showed larger values in the case of the filled systems of MMA‐grafted perlite than in the case of the unmodified perlite. (3) At the same total volume fraction which was the sum of the quantities of the perlite and the grafted PMMA, the relative viscosity and the crowding factor showed respectively a maximum with the quantity of grafted PMMA. (4) The shear compliance of these filled systems decreased with perlite content. A little effect of the amount of grafted PMMA on the compliance was observed at the same volume fraction of perlite. According to these rheological properties, it could be concluded that the grafted PMMA chains were effective in increasing the interaction between the ionomer matrix and the perlite at their interface, particularly in the lower shear rate region. Copyright © 1979 John Wiley & Sons, Inc.