Compressional Behaviour of an Agglomerated Cellulose Powder

The ability of an agglomerated cellulose powder to total and plastic deformation was evaluated and compared with those of Avicel PH 101, Emcocel and an experimental depolymerized cellulose powder. The elastic recovery of compressed cellulose tablets was also measured. The effects of deformation of the material during the tableting process and recovery of tablet after maximum compression on the mechanical strength of tablets were also discussed.

The apparent net work done into tablets during compression as well as the yield pressures to total and plastic deformation, determined from the Heckel treatment, showed no great differences between the agglomerated cellulose powder and the other cellulose powders. Thus all the cellulose materials studied had rather similar ability to total, i.e. elastic and plastic, deformation and to permanent, i.e. pure plastic, deformation. The obvious fragmentation of the agglomerated cellulose powder already at low compressional pressure, however, seemed to be advantageous for the formation of strong compacts.

Both rapid and total elastic recovery of compressed cellulose tablets showed clear differences between the cellulose materials and these differences correlated with the previously measured strength of cellulose tablets. The agglomerated cellulose powder had the smallest tendency to both kind of elastic recoveries of tablets. Obviously, due to the large interparticle contact areas, the ability of this material to establish more bonds between adjacent particles during compression was greater than those of other celluloses. The elastic recovery was greatest for depolymerized cellulose tablets indicating the poorest binding ability of the particles of this material.