Effect of molecular mass on the melting temperature, enthalpy and entropy of hydroxy-terminated PEO

P. J. Sánchez-Soto, J. M. Ginés, M. J. Arias, C. Novák, A. Ruiz-Conde

Research output: Contribution to journalArticle

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Abstract

This paper studies the effect of molecular mass on the melting temperature, enthalpy and entropy of hydroxy-terminated poly(ethylene oxide) (PEO). It aims to correlate the thermal behaviour of PEO polymers and their variation of molecular mass (MW). Samples ranging from 1500 to 200,000 isothermally treated at 373 K during 10 min, were investigated using DSC and Hot Stage Microscopy (HSM). On the basis of DSC and HSM results, melting temperatures were determined, and melting enthalpies and entropies were calculated. Considering the melting temperatures, it was found that the maximum or critical value of MW was found around 4000, and then these remain almost constant. This behaviour was interpreted assuming that lower MW fractions (MW4000), as folded chains. The melting enthalpies showed a scattering effect at least up to MW 35,000. It was difficult to obtain any relationship between melting enthalpies in J g-1 and MW. These variations seem to be of statistical nature. Corrected enthalpy data on a molar basis (kJ mol-1) exhibited a linear relationship with MW. Considering the solid-liquid equilibrium, the melting entropies (in kJ mol-1) were calculated. These values were more negative as compared with molar enthalpy increases. It was explained because the changes in melting temperatures are much smaller than those observed in the enthalpy values. Linear relationship between enthalpies and entropies as a function of MW was deduced.

Original languageEnglish
Pages (from-to)189-197
Number of pages9
JournalJournal of Thermal Analysis and Calorimetry
Volume67
Issue number1
DOIs
Publication statusPublished - 2002

Fingerprint

Molecular mass
Polyethylene oxides
Melting point
Enthalpy
Entropy
enthalpy
melting
entropy
Melting
temperature
Microscopic examination
microscopy
ethylene oxide
Polymers
Scattering
polymers
Liquids
liquids
scattering

Keywords

  • DSC
  • Melting enthalpies
  • Melting temperatures
  • Molecular mass
  • PEO polymers

ASJC Scopus subject areas

  • Chemical Engineering(all)

Cite this

Effect of molecular mass on the melting temperature, enthalpy and entropy of hydroxy-terminated PEO. / Sánchez-Soto, P. J.; Ginés, J. M.; Arias, M. J.; Novák, C.; Ruiz-Conde, A.

In: Journal of Thermal Analysis and Calorimetry, Vol. 67, No. 1, 2002, p. 189-197.

Research output: Contribution to journalArticle

Sánchez-Soto, P. J. ; Ginés, J. M. ; Arias, M. J. ; Novák, C. ; Ruiz-Conde, A. / Effect of molecular mass on the melting temperature, enthalpy and entropy of hydroxy-terminated PEO. In: Journal of Thermal Analysis and Calorimetry. 2002 ; Vol. 67, No. 1. pp. 189-197.
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