Application of X-ray microtomography to the description of single granules

The performance of agglomerated products is determined by their composition and structure [1]. For a given product, composition is usually fixed and the structure of the agglomerates is determined by the way they are manufactured. In this work, a commercial X-ray tomography PM: I) system was used in order to investigate the structure of individual agglomerates and how it is affected by different parameters during the granulation process. Qualitative analysis of cross-sectional images for different granulation systems show typical structures for different granulation methods (ranging from the opened structure of fluidised bed granules to the more compact high-shear granules). It is also shown that granules from the same batch can have different structures due to the coe3dstence of different granulation mechanisms during the granulation process. Further studies were carried out for high-shear melt granulation using calcium carbonate and polyethylene glycol as a model system. A method was developed to analyze XRT data in terms of radial profiles of greyscale intensity within the granules in order to provide information on their internal structure. Different process and formulation parameters were studied using this method alongside qualitative analysis of the images and dissolution/strength information. An increasing radial consolidation was observed in all cases. Higher impeller speed and longer granulation time increased the overall consolidation in the granules tested, resulting in stronger and slower to dissolve granules. The effect of formulation parameters was not dear in the radial profiles (XRT scans do not show dear structural differences due to resolution/ composition issues); but the effect was clear in the performance indicators: increasing primary particle size, binder molecular weight and binder to solid ratio resulting in stronger/more difficult to dissolve granule.