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K. Pielichowski, K. Flejtuch

Phase transitions of poly(ethylene oxide)/carboxylic acid blends able to storage of energy

Polimery 2004, No 3, 173


Summary

Melting - solidification phase transitions of various, differing in molecular weight, poly(ethylene oxide) (PEOX) samples and their blends with selected carboxylic acids (capric, lauric, myristic, palmitic or stearic one) have been investigated. The methods of differential scanning calorimetry (DSC) and modulated temperature DSC (MT-DSC) were used. Theoretical values of enthalpies of phase transitions of PEOX/stearic acid (KS) blends were calculated and compared with experimental data. For some ranges of both substances' concentrations the synergetic effect, expressed as increase in phase transition heat value, was found. The effect observed stimulates further application research works on new organic materials being able to storage of energy. The use of MT-DSC method allowed separating the reversing and nonreversing components of heat flow of melting and solidification processes. The results obtained let interpret the effect of PEOX and KS interaction on the mechanism of crystallization of these substances or their mixtures. This way additional information (in comparison with classical DSC method) concerning phase transitions occurring in PEOX/carboxylic acid systems during heating and cooling was obtained.


Keywords: poly(ethylene oxide), carboxylic acids, blends, phase transitions, modulated temperature differential scanning calorimetry, heat storage systems


K. Pielichowski, K. Flejtuch

Phase transitions of poly(ethylene oxide)/carboxylic acid blends able to storage of energy