The effect of die wall temperature on the flow of polymer melts in circular capillary dies was studied. At constant flow rates, it was found that die wall temperature had a greater effect on the pressure drop than melt temperature. A capillary die with two circular channels with different diameters was designed to simulate the profile extrusion. Changes of wall temperature varied the flow rate ratio between the two channels. An implicit finite difference method was used to simulate the velocity and temperature profiles inside the die. Values predicted by this model matched well with experimental data for both dies.
In this work, we analyzed the non-isothermal flow of polymer melt in circular channels. An implicit finite difference method was used to describe the effect of die wall temperature on the flow of polymer melts. The model success- fully predicts die pressure changes and flow rates under different wall temperatures for various capillary dies. Combined with the experimental results, we conclude that:
1. Increasing the die wall temperature decreases the die pressure drop when the flow rate of the polymer melt is kept constant. Die temperature has a greater effect on the pressure drop than that of melt temperature.
2. For the two-hole die, because of the temperature- dependent viscosity, increasing the die wall temperature tends to shift more material flowing through the small channel, while decreasing the die wall temperature tends to shift more material flowing through the larger channel.[1]
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