Adhesion of suspension particles on the wall surface of the container

Summary

The mechanism of the adhesion of the suspension particles on the wall surface of the glass container is discussed. Two types of mechanism are found; 1) simple adhesion where no mutual affinity or interaction exists between the particle and the wall, 2) adhesion with affinity.

In the case of the simple adhesion, the suspension particle is pressed against the wall and trapped by a thin medium film, whose pressure increases with decreasing of the medium film thickness. Important in this process is the liquid film formation on the wall. Under the pressure, the particle superdissolves into the thin liquid film at the contacting point, and the excess particle component produced deposits on both surfaces of the wall and the particle, where no direct pressure works upon. The adhesion strength increases as time goes by, since the deposition grows according to time, as long as the medium film presents and the pressure works on the particle. Adhesion due to deposition is not so popular as that due to affinity, but it is considered as an important basic form of the adhesion.

For the affinity adhesion, the commonest affinity is a hydrophobic bonding effect, which may be explained byvan der Waals coefficient and by determination of sliding angle of the suspension particle in the dispersion medium. Electrostatic affinity is less popular than affinity by hydrophobic bonding, but adsorption of the medium component onto the particle or the wall sometimes causes the adhesion due to this. Zeta potential of chloramphenicol crystals and glass powder was measured and its influence on the adhesion was discussed in connection with adsorption of benzethonium chloride. It was found that the adhesion strength of this type does not increase with lapse of time.