TROUTON VISCOSITY OF POLYPROPYLENE IN THE MELT SPINNING PROCESS
1968 Volume 24 Issue 4 Pages 147-154
Details
1968 Volume 24 Issue 4 Pages 147-154
Distribution of temperature and diameter of isotactic polypropylene filaments were measured in the quenching process in melt spinning. Typical experimental data are shown in Fig. 4. Trouton viscosity was obtained from the values of dlogu/dl in Fig. 4, where u is the spinning velocity and l is the distance from the spinnerette using eqs. (3) and (4). Drag force contribution in eq. (4) is evaluated by eq. (6)6).
Trouton viscosity is shown in Fig. 5 as Arrhenius plot of log λ vs. 1/T, which is classified into 3 groups of intrinsic viscosity [η] of the polymer. There were no effects of spinning velocity (100_??_500m/min), and polymer out-put (0.5_??_2.0g/min. nozzle hole). Curves of log λ vs. 1/T are presented with 2 linear lines divided at 130°C and the apparent activation energy ΔH is evaluated as shown in Fig. 6. In the range of temperature higher than 130°C, ΔH was 4.5_??_7.5 kcal/mol, comparable with ΔH of shear viscosity 8.7 kcal/mol7). In at the lower temperature range (<130°C), ΔH increases to the values of 12_??_17 kcal/mol, due to the formation of _??_ber structure (orientation and crystallization). The effects of [η] on trouton viscosity is evaluated as the power of 3.0_??_4.3 as shown in Fig. 7.
Theoretical equation of trouton viscosity for non-Newtonian liquid was presented by Bird5) as:
λ=3μ0[1+(τ1-τ2)]du/dl
In this experiment, there was no effect of du/dl (less than 30_??_/sec), and this indicates the difference of relaxation and retardation time constant (τ1-τ2) is less than 10-3 sec. Observed values of λ were compared with the those of 3-times zero shear viscosity7) as shown in Fig. 8.
