The effect of moisture on the cohesive properties of microcrystalline celluloses.

A comparative evaluation of two microcrystalline celluloses, Avicel PH101 and Emcocel, revealed some differences in their cohesive properties at different moisture contents. A new method of sandwich rheometry was used to evaluate the cohesive properties of different powder masses. The force required to cause shear failure of a rough-surfaced blade in a powder bed was recorded. Avicel PH101 was found to be more cohesive than Emococel at moisture contents less than 30 wt%, whereas at higher moisture contents the cohesive behaviour was comparable.