EFFECT OF TEMPERATURE HISTORY UPON STABILITY AND MELTING OF POLY(ETHYLENE OXIDE)

The effect of temperature history upon the distribution of molecular w eights and melting points has been investigated with high-molecular po ly(ethylene oxides). The results obtained by the size exclusion chroma tography (SEC) and differential scanning calorimetry (DSC) have shown that a long-term annealing of high-molecular poly(ethylene oxides) res ults in a distinct degradation of polymeric chains. The change in dist ribution of molecular weights and the presence of oligomers formed by degradation markedly affect the melting points of poly(ethylene oxide) . The diffusion of oligomers from crystalline into amorphous regions i s manifested by a time change of melting point and crystallinity degre e of poly(ethylene oxide). The degradation is also observed during X-r ay measurements.