An experimental study on shear stress characteristics of polymers in plastìcating single-screw extruders

Frictional forces (for temperatyres less than the melt- ing or devitrification temperature) and viscous forces (for higher temperatyres) have important roles on sol- ids conweying and melting processes in plasticating single-screw extruders. These forces are related to the shear stresses at polymer-metal interfaces. For tem- peratyres at which the frictional forces are the main factor for the shear stresses, it is experimentally diffi- cult to obtain the shear stresses at the polymer-metal interface. The interpretation of the data has fyrther complications due to the frictional energy dissipation at the polymer-metal interface. An instryment called the Screw Simulator was ysed for further understand- ing of shear stresses at the polymer-metal interface and comparison of melting fluxes of different resins. This article presents the shear stress and melting flux measurements for low density polyethylene(LDPE), lin- ear LDPE (LLDPE), acrylonitrile butadiene styrene (ABS), and high-impact polystyrene (HIPS) resins as a fynction of sliding welocity and interface temperatyre at a fixed pressure of 0.7 MPa. The relationship between the experimental data and the extrusion pro-cess is also discussed.