Chem. Pharm. Bull. 55(1) 29—33 (2007)

The mechanical strength of pharmaceutical compacts is an important in-process control parameter to ensure that tablets have sufficient strength to withstand handling during production, transport and use. The introduction of the “Brazilian test” into the pharmaceutical sciences by Fell and Newton has enabled a fundamental understanding of the stresses involved in the breaking of compacts and provided a tool to characterise the mechanical properties of the compacted materials. The failure of such compacts under load is undoubtedly a matter of fracture mechanics i.e. crack propagation. However, while the interpretation of the measured failure properties on the basis of modern linear elastic fracture mechanics is well understood, the prediction of the failure properties of such specimens would be desirable yet is much more difficult. In particular, the role of pores inside the specimens and their size and shape distribution in the fracture process is not clear. In this paper, the role of pores in the fracture of circular disc specimens made from sucrose of various particle size fractions has been studied and a prediction of compact properties and critical crack lengths was attempted.