Abstract
The thermal properties of a perfluoropolyether (PFPE) W/O microemulsion were investigated by Differential Scanning Calorimetry (DSC) both on freezing the liquid samples and upon their melting. PFPE systems as a function of increasing volume fraction (Φ=water+surfactant/total), were studied along a dilution line with a water/surfactant molar ratio W/S=11. The percolative nature of these systems emerged directly from the spreading of the exothermic peaks associated with the freezing of the dispersed phase. This behaviour was found to depend on whether the starting temperature of the DSC measure was at, below or above the percolative threshold temperature of the given sample. A low temperature 'needle-like' peak was found around 143 K, immediately after the glass transition due to the oil continuous phase. The low temperature peak was also present in other percolative, three-component microemulsions. The higher order phase transition at the percolation temperature was also evidenced.
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Senatra, D., Gambi, C.M.C., Carlà, M. et al. Thermal Behaviour of Perfluoropolyether w/o Percolative Microemulsions. Journal of Thermal Analysis and Calorimetry 56, 1335–1346 (1999). https://doi.org/10.1023/A:1010106523289
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DOI: https://doi.org/10.1023/A:1010106523289