Effect of particle size and compaction load on interparticulate bonding structure for some pharmaceutical materials studied by compaction and strength characterisation in butanol

The remaining tensile strength (the strength of tablets in l-butanol divided by the strength in air) was used as a simplified measure;of bonding by solid bridges and/or mechanical interlocking. The remaining tensile strength is believed to provide information about interparticulate bonding structure. Weak distance forces appeared to play an important role in the bonding of all compacts. Bonding by mechanical interlocking has been suggested as a possible bonding mechanism for dicalcium phosphate dihydrate and microcrystalline cellulose. Solid bridges develop during compaction of sodium chloride tablets. Sodium bicarbonate and sodium chloride have similar chemical structures and volume reduction behaviour. However, due to the more complex intraparticulate chemical structure, solid bridges probably do not develop to a large extent in sodium bicarbonate compacts. Weak distance forces are probably the most important bonding mechanism for lactose and sucrose. Decreasing particle size and increasing compaction load appear to decrease bonding by mechanical interlocking in materials where this type of bond is possible. Increasing particle size and compaction load in sodium chloride compacts facilitates the development of solid bridges. However, the compaction load and particle size do not seem to have any major effect on the bonding structure in lactose and sucrose compacts. (C) 1997 Elsevier Science B.V.