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and finally the pressure drop Ap from Equation 5.2
Example 3
Melt flow through a slit with width W = 25 mm, height H= 5 mm, and length L = 100 mm.
The resin is LDPE with the same viscosity constants as in Example 1. The mass flow rate
m = 10 g/s and the melt temperature T = 200 0 C. The pressure drop Ap is to be calculated.
Solution
Volume flow rate
Shear rate ya from Equation 5.10:
Shift factor ar from Equation 1.34:
Power law exponent n from Equation 1.37:
Viscosity 7]a from Equation 1.36:
Shear stress T from Equation 1.22:
Proportionality factor K from Equation 1.26:
Correction factor Fp:
As the ratio W/H = 5, which is less than 20, the die constant Gslit has to be corrected.
Fp from Equation 5.5:
Pressure drop Ap from Equation 5.2: