HOLOGRAPHIC EVALUATION OF BENDING AND INTEGRITY OF PHARMACEUTICAL POWDER BEAMS

Double-exposure holographic interferometry was used to detect structur al uniformity and bending properties of compressed rectangular beams c onsisting of microcrystalline cellulose, dicalcium phosphate dihydrate and a-lactose monohydrate. The fringes in holographic reconstructions produced a clear pattern for interpretation of bending without any co mplication. Thus, it was possible to calculate the elastic modulus val ues for both the upper and lower surfaces of the sample beams. The the oretical bending profiles versus experimental bending data were also e valuated. It was possible to detect unpredictable changes due, for exa mple, to structural non-homogeneities and induced stress. The induced stress inside the beams had a slight effect on the ideal bending, due to the fixing of the beam. The modulus values obtained from extrapolat ion to zero porosity were in good agreement with the previously publis hed results. According to this study, double-exposure holographic inte rferometry is a suitable, accurate and versatile method for mechanical studies of pharmaceutical powders and compacts.