Preferred Orientation of Crystalline Particles within Tablets. III. Change in Degree of Preferred Orientation of Aspirin Crystals during Compression

Abstract

The degree of preferred orientation of aspirin crystals in a tablet as a function of compression force was measured using the X-ray diffraction method. Preferred orientation took place during compression and the degree was affected by the size and morphology of the crystals. Thin, plate-like crystals had the strong tendency to orient preferentially at an early stage of compression, while pulverized crystals oriented gradually at over 100 kg/cm² of the compression force. In addition, volume, specfic surface area, pore size distribution and breaking strength of the tablets were measured and the relationship among these factors was investigated.