Abstract: The polymer melts viscous dissipation effects of micro scale dimensions are different from that of macro-scale dimensions. The affect of viscous dissipation in micro injection molding on the rheological behavior of melts is analyzed by using the basic rheological theory of polymer melts. The viscous dissipation measurement device is designed on the basis of two-cylinder capillary rheometer. Experimental studies of viscous dissipation at various shear rate are investigated with several polymers, including achylonitrile butadiene styrene and high density polyethylene, at different temperature when melts flow through 500 μm size diameter micro channel. The results indicate that the temperature rise caused by viscous dissipation increases with increasing shear rate and the temperature rise for some shear rate decreases with increasing melts temperature. The theoretical calculation of viscous dissipation reveals that the viscosity of melts near wall reduces obviously with increasing shear rate. Therefore the influence of viscous dissipation should not be neglected when the theoretical model of mold filling flow in micro injection molding is established.

Key words: Micro injection molding, Micro scale, Polymer melts, Rheological measurement, Viscous dissipation