Answer Happy

Q4. a) Flow curves for a polyethylene melt at 170°C are presented in Fig. 24.1. Clearly show how this data may be used to calculate the Power Law index (n) for the melt as 0.33? [5 marks) b) A polyethylene melt at 170°C flows through the channel shown in Fig. 24.2. Calculate the total pressure loss along the channel if the volume flow rate of the melt is 7.5 x 106m/s. You may use the flow curves given in Fig. 24.1. [17 marks) 12 mm Meit Flow 6.4 mm Included Angle - 6 deg 150 mm 12.5 mm Fig Q4.2 - Tapered Die Section c) What effect is the length of the parallel section likely to have on the swelling as the melt emerges from the die? [3 marks)
1E+006 Tensile modulus 100000 Tensile viscosity Shear modulus 10000 Figure 24.1. Flow Curves for Polyethylene at 170°C (Ns/m2 or N/m2) 1000 Shear viscosity Onset of non-laminar flow in unstreamlined dies 100 0.1 10 1000 10000 100 Strain rate (s)
Q4(b) 12.49 MPa