Effects of glass formation by solvents in differential scanning calorimetry investigations of solvent swollen coals

M.M. Antxustegi, A.J. Mackinnon, P.J. Hall

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The behavior of solvents under conditions of rapid cooling is investigated. It is demonstrated that certain coal solvents form glasses on quenching at 60 K/min whereas others form crystals. In swollen coals, most free solvents tend to go into glassy states. An important exception is pyridine. The formation of glasses by free solvents has two effects on differential scattering calorimetry results. At temperatures below the solvent melting point, exotherms are produced. This is probably due to cold recrystallization. At high solvent weight fractions, second-order phase transitions may occur, which are not a feature of the coal. It is concluded that investigations of phase transitions in swollen coals should preferably be performed at the ''gel'' point, with no free solvent present. It is shown that low-temperature second-order phase transitions for quenched solvents occur at the same temperature as in coal gels formed with the same solvents. This suggests that phase changes in the solvents determine the form and temperature of the glass transitions.
LanguageEnglish
Pages1026-1029
Number of pages3
JournalEnergy and Fuels
Volume7
Issue number6
DOIs
Publication statusPublished - Nov 1993

Fingerprint

Coal
Differential scanning calorimetry
Glass
Phase transitions
Gels
Temperature
Calorimetry
Pyridine
Melting point
Glass transition
Quenching
Scattering
Cooling
Crystals

Keywords

  • macromolecular structure
  • temperature
  • transitions
  • coals

Cite this

Antxustegi, M.M. ; Mackinnon, A.J. ; Hall, P.J. / Effects of glass formation by solvents in differential scanning calorimetry investigations of solvent swollen coals. In: Energy and Fuels. 1993 ; Vol. 7, No. 6. pp. 1026-1029.
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Effects of glass formation by solvents in differential scanning calorimetry investigations of solvent swollen coals. / Antxustegi, M.M.; Mackinnon, A.J.; Hall, P.J.

In: Energy and Fuels, Vol. 7, No. 6, 11.1993, p. 1026-1029.

Research output: Contribution to journalArticle

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AU - Mackinnon, A.J.

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N2 - The behavior of solvents under conditions of rapid cooling is investigated. It is demonstrated that certain coal solvents form glasses on quenching at 60 K/min whereas others form crystals. In swollen coals, most free solvents tend to go into glassy states. An important exception is pyridine. The formation of glasses by free solvents has two effects on differential scattering calorimetry results. At temperatures below the solvent melting point, exotherms are produced. This is probably due to cold recrystallization. At high solvent weight fractions, second-order phase transitions may occur, which are not a feature of the coal. It is concluded that investigations of phase transitions in swollen coals should preferably be performed at the ''gel'' point, with no free solvent present. It is shown that low-temperature second-order phase transitions for quenched solvents occur at the same temperature as in coal gels formed with the same solvents. This suggests that phase changes in the solvents determine the form and temperature of the glass transitions.

AB - The behavior of solvents under conditions of rapid cooling is investigated. It is demonstrated that certain coal solvents form glasses on quenching at 60 K/min whereas others form crystals. In swollen coals, most free solvents tend to go into glassy states. An important exception is pyridine. The formation of glasses by free solvents has two effects on differential scattering calorimetry results. At temperatures below the solvent melting point, exotherms are produced. This is probably due to cold recrystallization. At high solvent weight fractions, second-order phase transitions may occur, which are not a feature of the coal. It is concluded that investigations of phase transitions in swollen coals should preferably be performed at the ''gel'' point, with no free solvent present. It is shown that low-temperature second-order phase transitions for quenched solvents occur at the same temperature as in coal gels formed with the same solvents. This suggests that phase changes in the solvents determine the form and temperature of the glass transitions.

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