Dispersant is a kind of surfactant, mainly to play the role of dispersion, its attachment to the particles, so that the mutual particles between a repulsive force, so that the particles are not easy to produce re-aggregation, that is, we see from the surface of the flocculation.
We usually use dispersant and wetting agent with the use of wetting dispersant, which is often seen in the wetting dispersant, wetting agent in which plays a leading dispersant into the various gaps in the particles, so that the dispersant to make all the particles separated, so that all particles suspended in the system.
According to the formula proposed by Ross:
Penetration coefficient E=Ys+DF-Yb≥0(3-7)
Spread coefficient S=Ye-Yp-Yp>>0(3-8) where Yr-the surface tension of the foam medium;
The surface tension of Yo-defoamer;
Y DF—The interfacial tension between the foam medium and the defoamer.
In order to produce infiltration, E must be greater than 0. In order to produce dispersion, density polyethylene wax S must be greater than 0. Only when the E value and S value are both greater than 0, the defoamer can have defoaming effect. In order to ensure that E is a sufficiently large positive value, it can be seen from formula (3-7) that Yp must be sufficiently small, that is, the surface tension of the defoaming itself should be small. In order to ensure that S is a sufficiently large positive value, it can be seen from equation (3-8) that not only y must be small, but also Y oF must be small, that is, the interfacial tension between the foam medium and the defoamer should also be low. This requires that the defoamer itself should have a certain degree of hydrophilicity, so that it is insoluble in the foaming medium and can be dispersed well. The surface tension and interfacial tension of water and 4 kinds of organic compounds at 20℃.
Surface tension and interfacial tension of 4 kinds of organic compounds/(mN/m)
The surface tension of organic compounds, the corresponding interfacial tension data and the surface tension value of water are substituted for formula (3-7) and formula (3-8), and their penetration coefficient and dispersion coefficient can be calculated.
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