Influence of Charging Materials on the Rheological Behawor of High-Density Polyethylene Melts

Abstract

The article presents the results of experimental studies on the rheological behavior of high-density polyethylene (HDPE) filled with calcium carbonate (25-125%) treated with surface-activating agents (a sort of high-density polyethylene with low molecular weight). Treating of the charge surface was realized by mixing (rapid Henschel mixer, 2 h, 60°C); then, the obtained recipes were submitted to granulation (Ko-Buss PR 40 type granulation installation). The rheological study was performed on a laboratory single-screw extruder especially equipped with a rheological nozzle having a measuring ring with four interchangeable bypasses. Six obtained recipes were processed in 28 regimes of shear rates, at a rotation speed ranging between 25 and 85 rpm and a temperature of 195°C. The influence of the filler on HDPE melts was investigated; it was established that the filler intensifies the viscous component, and for concentrations over 25%, it modifies the elastic component of the polymer substantially. The surface treating of the filler modifies the comportment of the matrix substantially: The tension threshold is reduced to elimination and the elastic component is strongly modified.