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Pressure drop from Equation 5.2:
Example 2
Melt flow through a slit of width W = 75 mm, height H = 1 mm, and length L = 100 mm.
The resin is LDPE with the same viscosity constants as in Example 1. The mass flow rate
and the melt temperature have the same values, m = 10 g/s and T = 200 0 C. The pressure
drop Ap is to be calculated.
Solution
Volume flow rate
Shear rate from Equation 5.10:
Shift factor aT 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 is greater than 20, the die constant which can be calculated from
Equation 5.4 need not be corrected.