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Treatment of water-induced curvature of the DSC heat flow rate signal Applied to fractionated nucleation of polypropylene dispersed in water

Tijdschriftbijdrage - Tijdschriftartikel

In samples containing a volatile phase, quite often the evaporation of the volatile substance during heating causes appreciable curvature of the DSC heat flow rate signal as function of temperature, making it difficult to quantify thermal transitions and reorganization phenomena occurring in the same temperature range. This is the case for e.g. polyamide-water, polyamide-alcohol, and polypropylene-water systems, thus complicating the study of polymer crystallization, melting, and metastability by DSC. In this study, maleic anhydride-grafted polypropylene particles of sub-micrometer diameters dispersed in water are discussed. These samples show, upon cooling from the melt, different degrees of extra supercooling in crystallization and several phenomena in the subsequent heating, like reorganization of a crystalline phase into another one, perfecting of crystallites, and melting. All these phenomena are difficult to analyze quantitatively due to the mentioned curvature of the DSC trace. In this article two methods, the "Reference" and "Extrapolation from the melt" methods, are described to correct for the influence of evaporation on the DSC heat flow rate signal and for the baseline signal, enabling the discussion of the transitions by way of the excess heat flow rate as function of temperature. © 2011 Akadémiai Kiadó, Budapest, Hungary.
Tijdschrift: Journal of Thermal Analysis and Calorimetry
ISSN: 1388-6150
Issue: 1
Volume: 106
Pagina's: 285 - 298
Aantal pagina's: 14
Jaar van publicatie:2011
Trefwoorden:Analytische, anorganische en nucleaire scheikunde, Fysische scheikunde