Sticky region in drying - definition and identification

A device has been developed, to characterize the stickiness of materials prone to shearing that is based on torque measurement during intermittent stirring. Experiments were carried out, using materials of various origin, and over a range of moisture contents that span the pasty to free-flowing powder consistencies. To reflect the complex nature of stickiness, often noted by researchers during the drying of slurries and pastes, the concept is proposed, of a stickiness region, adjacent to the stickiness curve. Referring to the two-dimensional visualization of a drying process with evolving moisture content and material temperature, possible trajectories are suggested, to deal with the stickiness problem.