Physical Processes - Isoconversional Kinetics of Thermally Stimulated Processes - page 151

0.0

-0.5

-1.0

0.5
1
1.5
2
3
5

-1.5

-2.0

-2.5

-3.0

55 60 65 70 75 80 85

T / o C

Fig. 3.76 DSC curves for the thermal denaturation of collagen in water measured at different
heating rates. Numbers by the lines represent the heating rate in ﾰC min −1 . (Reproduced from
Vyazovkin et al. [ 185 ] with permission of Wiley)

Total
Non-reversing
Reversing

55 60 65 70

T / o C

Fig. 3.77 Temperature-modulated DSC data for the thermal denaturation of collagen. The total,
nonreversing, and reversing heat flow are respectively presented by solid, dash, and dash-dot
lines . (Reproduced from Vyazovkin et al. [ 185 ] with permission of Wiley)

The application of an isoconversional method to the DSC data on thermal dena-
turation of collagen (Fig. 3.76 ) results in the E ʱ dependence seen in Fig. 3.78 . Since
the conversion increases with increasing temperature, the estimated dependence
is consistent with the temperature dependence for the effective activation energy
predicted by the Lumry-Eyring model. Undoubtedly, the model is suitable to ex-
plain the obtained isoconversional dependence of the effective activation energy.
The question is whether it is suitable to extract accurate estimates of the intrinsic
parameters from the E ʱ dependence.