Based on the theoretical analysis of viscous dissipation effect when polymer melt flowing in micro injection mold

the change of the melt temperature of the polypropylene (PP) and high density polyethylene (HDPE) caused by the viscous dissipation effect were tested and simulated in the rectangular cross section micro channels with different equivalent diameters and ratios of length to diameter under a variety of process parameters. The results showed that the theoretical calculation and numerical simulation values were highly consistent with the test results

and the average errors were all less than 1℃. The study found that when the equivalent diameter and ratios of length to diameter were increased

the heat of viscous dissipation increased

thus the outlet temperature of channel rose. When the geometry size of the micro channels remains unchanged

the viscous dissipation heat increased with the increase of the injection speed and injection pressure

and decreased with the increase of the melt temperature and mold temperature. But under the same test condition

the viscous dissipation heat of PP material which is more sensitive to shear was obviously higher than that of HDPE.