VISCOUS PROPERTIES OF CALCIUM-CARBONATE FILLED POLYMER MELTS

The viscous properties of calcium carbonate filled polyethylene and polystyrene melts were examined. The relative vircosity ηr defined in the previous paper gave an asymtptotic value (ηr)l in the range of the shear stress below 105 dyne/cm2. (ηr)l of the calcium carbonate filled system was higher than that of the glass beads or glass balloons filled system at the same volume fraction of the filler φ. Maron-Pierce equation with φ0 = 0.44 was able to approximate the (ηr)l - φ relationship. However, it was deduced here that the high value of (ηr)l of calcium carbonyl filled system was due to the apparent increase of φ and this increase was attributed to the fixed polymer layer formed on the powder particle. By assuming the particle as a sphere with a diameter of 2 μm, the thickness of the fixed polymer layer was estimated as about 0.17 μm. The yield stress estimated from the Casson's plots increased exponentially with φ. © 1979 Dr. Dietrich Steinkopff Verlag.