Dimensional changes of compacts after compression.

A non-contact optical technique has been used to measure changes in the heights and diameters of compacts prepared from sodium chloride, spray dried lactose, two samples of methylcellulose powder and two spray-dried lactose-maize starch granulations. Both sodium chloride and spray dried lactose exhibited relatively small dimensional changes whilst the methylcellulose powders showed up to 30% axial and 3% radial expansion. The results are discussed in terms of the inherent properties of the materials. When the lactose was granulated with maize starch, the ratio of axial; radial strain recovery was reduced from 5-9:1 to approximately 1:1, suggesting an improved distribution of forces during compression of the granulations,