1977 年 26 巻 288 号 p. 858-862
The interaction force between microparticles was measured with an electrobalance directly in various atmospheric conditions, particularly in the humidity controlled air, nitrogen and vacuum. The interaction force of glass microspheres in a dried atmosphere changed inversely as the square of the distance between two particles. It was considered that the attractive force was resulted from the Coulomb force between the particles. However, it was difficult to establish the relation between the attractive force and the particle size, because the attractive force was influenced strongly by the experimental condition.
The interaction force between the hydrophilic particles in humid air was so little as to be neglected when the particles were brought close together. But the cohesive force of the particles needed to separate them each other was larger than the Coulomb force and it varied with humidity of air. The cohesive force did not change at the lower humidity range, but increased rapidly at the humidity of 60% or above. These results suggest that in a humid atmosphere the interaction force between the particles results from the capillary condensation of water vapor associated with the contact of two particles.