The temperature increase of polyformaldehyde(POM)and polystyrene(PS)melts at the outlet of circular and rectangular micro-channels with the same aspect ratio and diameter/equivalent diameter of 350 and 500 μm was measured at different shear rates using two-cylinder capillary rheometer and self-developed viscous dissipation measurement device.The viscous dissipation and its effect on flow behavior of polymer melt in micro-channels were investigated.The results show that the viscous dissipation is enhanced obviously with the increase of shear rate and diameters/equivalent diameter value in the micro-channels.The viscous dissipation in the rectangular channel is much stronger than that in the circular one.Under the same experimental conditions

the temperature increase at the outlet of crystalline POM melt is larger than that of amorphous PS melt due to viscous dissipation.