Question

2.) A capillary rheometer is used to measure viscosity. A pressure transducer records the pressure drop delta P across the die, and the die capillary has a diameter of 2 mm. Experiments are carried out at three volume flow rates Q, for dies of each of three lengths l. The following is a table of values of delta P (in MPa) measured for polupropylene at 190 C. For each flow rate Q find the apparent viscosity, assuming Newtonian behaviour.

Table 7.3 ?? values for various values of I and Q in Problem 7.6 Q=4 (10-7 m3/s) (10m3s) (10-7 m/s) 0- 2 1-5 mm 10 mm l = 20 mm 1.502 2.337 4.006 2.100 3.266 5.599 2.935 4.565 7.826

Answer 1

uirena T,o= shan-stress TR3 Tw.es sle he哧or vs uk grobl~ 2x15구 4x10-7 8x1。7 o.ICES O 2 333 o 32 Tu

L(mm) L/R 1.502 2.337 4.006 2.1 3.266 5.599 2.935 166900 4.565 233300 7.826 326100 shear rate 254 509.5 1019 10 20 10 20 y 0.3261x1.3045 у-0.2333x + 0.9335 4 Series1 y0.1669x + 0.66 10 15 20 25 Shear stress Vs Shear rate 350000 300000 250000 200000 150000 100000 50000 y-204.41x + 1206 Shear stress Vs Shear rate inear(Shear stress Vs Shear rate) 400 600 Apparent Shear Rate 200 800 1000 1200