Characterization of the crystallization behavior of the eutectic-forming binary system polyoxyethylene and glutaric acid. I. melting and crystallization behavior

The crystallization characteristics of the binary system polyoxyethylene (PEO)-glutaric acid were determined. From the extrapolated melting point depression data the heat of fusion for PEO is 2506 ± 200 cal/mole of repeat unit while the heat of solution for the glutaric acid amounts to 6.7 ± 1.2 cal/cm³. A melting point of 348 K is found for the high-molecular-weight PEO. A calorimetric glass-transition temperature for mixtures of the two components is relatively independent of the melt composition and appears at 217 K. A eutectic is observed whose composition and melting temperature depend on the nature of the PEO crystal phase.