The plasto-elasticity and compressibility of coated powders and the tensile strengths of their tablets.

A study has been made of the effects produced on the tensile strength, brittle fracture index (BFI), 'plasto-elasticity' ratio, ER/PC, and yield pressure (1/KH derived from Heckel plots) of sodium salicylate and calcium carbonate as a result of coating their particles with increasing amounts of silicones and polysorbates before subjecting them to compression to form tablets. The coatings act as lubricants reducing bond formation due to plastic deformation of particles. They caused a reduction in the tensile strengths and yield pressures of the tablets but increased their BFI values and their ER/PC ratios. Tablets of calcium carbonate tended to cap or laminate when their BFI value was greater than 0.7 and their ER/PC ratio was greater than 7. Sodium salicylate whose BFI values were all less than 0.7 produced satisfactory tablets when their ER/PC ratio was less than 10 but tended to cap or laminate when it was greater than 10.