Abstract
A theory of the tensile strength of powders caused by moisture in the pendular state is derived. It also incorporates the effect of powder density and particle size distribution. It has only been possible to test the theory in a limited way (by comparison with experimental results obtained with poly-vinyl chloride powders of a given size fraction containing 6 to 17% of moisture) because published data do not include all the required information. The usefulness of the theory is, therefore, in indicating the parameters and factors that should be covered in any future experimental investigation into the effect of moisture on tensile strength.