Sucrose enthalpy relaxation

Structural relaxation times determined from enthalpy relaxation studies with sucrose and trehalose [37,50] are given in Figure 8. The structural relaxation times observed are qualitatively similar to those estimated for the fragile glass... 

Figure 8 Structural relaxation times for quench-cooled glassy disaccharides as determined from enthalpy relaxation data. Structural relaxation times were obtained by a fit of the data to the stretched exponential function (see [37,50]). ( ) Data for sucrose obtained by differential scanning calorimetry on annealed samples [37], (O) Data for sucrose obtained by isothermal microcalorimetry [50]. (A) Data for trehalose obtained by isothermal microcalorimetry [50].

Shamblin, S.L. and Zografi, G. Enthalpy relaxation in binary amorphous mixtures containing sucrose, Pharm. Res., 15, 1828, 1998. 

Enthalpy Relaxation in Freeze-Concentrated Sucrose-Water Glasses... 

The objective of the present study is to investigate enthalpy relaxation of a very common model food system, sucrose-water, by using DSC. In accordance with the previous study, the Kohlraush-William-Watts (KWW) equation is applied to calculate the relaxation time and the activation energy of the enthalpy relaxation. 

The enthalpy relaxation, AH (J/g 80% sucrose), and aging time. Dashed lines were obtained by fitting of the KWW equation. 

Kawai, K., Hagiwara, T., Takai, R., and Suzuki, T. Comparative investigation by two analytical approaches of enthalpy relaxation for glassy glucose, sucrose, maltose and trehalose, Pharm. Res., 2004, in press. 

Structural relaxation times determined from enthalpy relaxation studies with sucrose and trehalose [39,53] are given in Figure 8. The structural relaxation times observed are qualitatively similar to those estimated for the fragile glass example in Figure 7. While there is considerable scatter in the data, it seems clear that the temperature dependence for sucrose is nonlinear and therefore non-Arrhenius. Insufficient data are available for trehalose to judge linearity. The trehalose structural... 

Aso Y, Yoshioka S (2006) Molecular mobility of nifedipine-PVP and phenobarbital-PVP solid dispersions as measured by C-NMR spin-lattice relaxation time. J Pharm Sci 95 318-325 Aso Y, Yoshioka S, Kojima S (2000) Relationship between the crystallization rates of amorphous nifedipine, phenobaibital, and flopropione, and their molecular mobility as measured by their enthalpy relaxation and H NMR relaxation times. J Pharm Sci 89 408-416 Aso Y, Yoshioka S, Zhang J, Zografi G (2002) Effect of water on the molecular mobility of sucrose and poly(vinylpyrrolidone) in a colyophUized formulation as measured by C-NMR relaxation time. Chem Pharm Bull 50 822-826... 

Fig. 4 (A) DSC scan of the glass transition temperature of a miscible blend of a MK-0591 with 10% PVP, showing the onset, midpoint, and offset glass transition temperatures. (B) DSC scan of the glass transition of sucrose with the enthalpic relaxation endotherm and enthalpy (AHr). (From Ref...

Effect of aging time on the relaxation enthalpy for gelatinized starch at different sucrose contents 0% ( ), 5% ( ), 10% (A), and 20% ( ) at = 0.660 and for comparison for starch 20% sucrose ( ) equilibrated over P2O5 (error bars are confidence intervals). 

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