A High Temperature Annular Shear Cell was used to directly measure yield loci up to 500°C and to evaluate the effect of temperature on the macroscopic flow properties of powders. A theoretical framework was developed according to the particle-particle approach of Rumpf and Molerus. In particular, the tensile strength of the powder experimentally evaluated for fluid cracking catalyst, corundum and glass beads was related to the van der Waals forces acting between particles assuming alternatively elastic and plastic deformation at contact points. Both the assumptions provide correct order of magnitude results in terms of tensile strength if plausible value of the local curvature at contact points of particles is taken into account. Furthermore, both the increasing cohesive consolidation and the slight increase of the cohesive behaviour with the temperature suggest the occurrence of the plastic deformation of the contact points and, therefore, that the plastic deformation assumption should be adopted to explain the effect of the temperature on the interparticle interactions
