COMPRESSION BEHAVIOR AND TENSILE-STRENGTH OF HEAT-TREATED POLYETHYLENE GLYCOLS

The compression behavior and tensile strength of five heat-treated pol yethylene glycol (PEG) powders of different average molecular weights were determined. Compacts were prepared at various compression pressur es using three different size fractions. The compression behavior of t he compacts was analyzed according to the Kawakita, Cooper-Eaten and H eckel methods, respectively, and their compression parameters were cal culated. Compared to the other polymers, PEG 4000 underwent greater de nsification during compression. The yield pressure from the slope of t he Cooper-Eaten plot was lowest for PEG 4000. The yield pressure deter mined via the Heckel method was found to be proportional to the molecu lar weight of the PEG. These polymers obey a Heckel relationship at lo wer pressures (not exceeding 80 MN/m(2)) and exhibit a behavior simila r to those of fatty acid powders. The specific surface area of the com pacts decreased with increasing compression pressure. The change in sp ecific surface area of compacts compressed at pressures greater than 8 0 MN/m(2) was only very slight. This indicates that the surface of the compacts melts at such pressures. At pressures above 26.53 MN/m(2), P EG 10 000 compacts had superior tensile strength compared to the other polymers.