chemia - Studia

THE RHEOLOGICAL STUDY OF SOME SOLUTIONS BASED ON SURFACE-ACTIVE AGENTS (II)
Table 5. Rheological equations for PC 1-5 solutions
Temperature, Equation
˚C PC 1 PC 4 PC 5
25 0. 414
τ = 1.4
⋅ & γ
32 0. 618
τ = 0.25
⋅ & γ
39.5 0. 802
τ = 0.04
⋅ & γ
τ = 19.7
⋅ & γ
τ = 3.9
⋅ & γ
τ = 0.55
⋅ & γ
0.185
0.500
0.810
τ = 6.6
⋅ & γ
τ = 2.1⋅
& γ
τ = 0.74
⋅ & γ
0.439
0.630
0.715
Through the measurements achievement at different temperatures it
was possible to establish the dependence lnτ
= f (1 T ) and to calculate the
E
a
values. For PC 1-5 solutions, the E
a
changes with the content of surfactant B
is shown in Figure 4. It is observed that there is a range of concentrations
−1
at which E has minimum values minimum values of (25 ÷ 65) kJ ⋅ mol .
a
140
Activation energy of viscous flow ,
kJ.mol -1
120
100
80
60
40
20
0
0 1 2 3 4 5 6
B content, w t %
27s-1 48.6s-1 81s-1
Figure 4. The activation energy evolution for PC 1-5 samples
2. The preservation time influence
That influence was studied for sample PC 2 at 32°C, and τ = f (γ&
)
dependence is presented in Figure 5. It can be observed that preservation
does not change the non-Newtonian behavior but increases the shear
stress values.
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