The compaction properties of polyethylene glycols.

The mechanical properties of polyethylene glycol (PEG) powders of different average molecular weights have been characterized in terms of their yield pressure, determined from the densification of compacts by the method of Heckel. The yield pressure was found to be proportional to the molecular weight of the PEG. The densification which occurred during compaction was greater the lower the molecular weight. In terms of compact tensile strength, PEG 10 000 produced the greatest strength for a given pressure. This arises from its ability to deform plastically to form a compact and be of sufficient intrinsic strength to resist fracture during the diametral compression test. Higher molecular weights PEGs do not allow sufficient plastic flow during consolidation for their inherent higher strength to be used.