| Autor: |
Sandra Prejac, Attilio Cesàro, Ranieri Urbani, Fabiana Sussich |
| Přispěvatelé: |
Urbani, Ranieri, F., Sussich, S., Prejac, Cesaro, Attilio |
| Rok vydání: |
1997 |
| Předmět: |
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| Zdroj: |
Scopus-Elsevier |
| ISSN: |
0040-6031 |
| DOI: |
10.1016/s0040-6031(97)00094-4 |
| Popis: |
The relaxation process of the sucrose in the glassy state and its glass transition are studied by differential scanning calorimetry in both the conventional and the dynamic mode. The data on the kinetics of glassy relaxation are experimentally evaluated by measuring the enthalpy relaxation peaks as a function of the ageing times at three different ageing temperatures, namely 45, 55 and 60°C. It is shown that the ageing process is a complex phenomenon with a rather large distribution of relaxation times. The value of the breath of the distribution of relaxation processes, β, is 0.32 and it is in the lower range of the distributions commonly observed. The dynamic components of the heat capacity ( C ′ p and C ″ p ) have been obtained from the experiments carried out at different frequency of temperature modulation ( ν =8.3−83 mHz). These components are unaffected by the ageing process and therefore are more reliable for the correct T g determination. The activation energies for the relaxation process and for the glass transition process are also evaluated. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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Full Text from ScienceDirect