CONSOLIDATION AND COMPACTION OF POWDER MIXTURES .2. BINARY-MIXTURES OF DIFFERENT PARTICLE-SIZE FRACTIONS OF ALPHA-LACTOSE MONOHYDRATE

Binary mixtures of different particle size fractions of alpha-lactose monohydrate were compacted into tablets. The results showed decreased crushing strengths and decreased internal specific surface areas of the tablets as compared with the values calculated by linear interpolation of the data obtained for the corresponding single powder fractions. The extent of decreased strength and decreased surface area of the tablets was found to depend upon the weight ratio of the finer sieve fraction in the blend and to increase with the diameter ratio between coarse and finer particles. These results indicate an interaction with respect to consolidation and compaction which is explained by decreased fragmentation potentials, caused by increased packing densities of the binary mixtures of different particle size fractions of crystalline lactose. All data on crushing strength and internal specific surface area of the tablets fitted the unique linear relationship between these parameters, as found previously for tablets compressed from binary mixtures of equal particle size fractions of different types of crystalline lactose.