A study on the progress of mutarotation above and below the Tg and the relationship between constant rates and structural relaxation times
PBN-AR
Instytucja
Wydział Matematyki, Fizyki i Chemii (Uniwersytet Śląski w Katowicach)
Informacje podstawowe
Główny język publikacji
angielski
Czasopismo
PHYSICAL CHEMISTRY CHEMICAL PHYSICS (40pkt w roku publikacji)
ISSN
1463-9076
EISSN
Wydawca
ROYAL SOC CHEMISTRY
DOI
URL
Rok publikacji
2017
Numer zeszytu
Strony od-do
20949-20958
Numer tomu
31
Identyfikator DOI
Liczba arkuszy
0,50
Streszczenia
Język
angielski
Treść
Comprehensive FTIR studies on the progress of mutarotation in D-fructose mixed with maltitol have been carried out over a wide range of temperatures, both above and below the glass transition temperature Tg. In addition to the analysis of single bands, we have developed a completely new approach considering the full spectral range to follow the overall progress of the reaction. We have found that at the calorimetric Tg, there is a clear change in the temperature dependence of constant rates. The activation barrier for mutarotation changes from around 59 kJ mol−1 (the supercooled state) to around 249 kJ mol−1 (the glassy state). This dramatic variation in the activation barrier is consistent with the change in the mechanism of this specific chemical conversion, as theoretically considered by Wlodarczyk et al. [Phys. Chem. Chem. Phys., 2014, 16, 4694–4698]. Alternatively, it can also be connected to the change in the viscosity of the sample. Additionally, we investigated the relationship between constant rates (k) of mutarotation, structural relaxation times (τα), and dc conductivity (σdc) above and below the glass transition temperature. It was found that there was a linear correlation between all these quantities; they scale with various exponents changing at Tg. Our results also indicate that a single activation barrier might not be sufficient to describe the mutarotation process.
Cechy publikacji
original-article
Inne
System-identifier
3342800136859
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