The effect of humidity of surrounding atmosphere on capillary adhesion forces in powders. Modelling and critical humidity

The effect of relative humidity of surrounding atmosphere on capillary adhe sion has been analysed taking into account various theoretical models of ad hesion process and different contact configurations between adjacent surfac es. It has been shown that for configuration systems including a spherical particle, there is no agreement between models predictions and experimental results both for values and trends of adhesion forces. A proper trend can be obtained from the models for a solid cone-fat surface system, but adhesi on force values calculated for a single contact point are too low. More acc urate model calculations require a contact point number function to be incl uded in the models due to roughness of real surfaces. The function can be o btained from surface engineering data.