chemia - Studia

THE RHEOLOGICAL STUDY OF SOME SOLUTIONS BASED ON SURFACE-ACTIVE AGENTS (II)
3%VAD; 25 o C
Apparent viscosity, Pa.s
0.4
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
8 8.5 9 9.5 10 10.5 11 11.5 12 12.5
VB content, wt %
81 s-1 243 s-1 437.4 s-1
Figure 7. The apparent viscosity vs. the VB concentration
Table 6. Rheological equations for PA 3-9 , PA 3-10 and PA 3-12 solutions (t =25˚C)
VB content, wt%
Equation
9 0. 824
τ = 6.5
+ 0.040 ⋅ & γ
10 0. 830
τ = 13.1+
0.034 ⋅ & γ
12 0. 740
τ = 27.4
+ 0.081⋅
& γ
The evolution of apparent viscosity of the solutions with 2%VAD and
different percentages of the VB (PA 2-7 and PA 2-10 ) is shown in Figure 8.
2%VAD; t=25 o C
Apparent viscosity, Pa.s
0.16
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
0 200 400 600 800 1000 1200 1400
Shear rate, s -1
7%VB
10%VB
Figure 8. The apparent viscosity vs. shear rate
The obtained viscosity curves, with apparent viscosity decreasing
with the increase of shear rate, show specific pseudoplastic behavior. It is
also found in this case that increase of VB amphiphilic surfactant concentration
253