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Poly(lactic acid). Группа авторов
Читать онлайн.Название Poly(lactic acid)
Год выпуска 0
isbn 9781119767466
Автор произведения Группа авторов
Жанр Химия
Издательство John Wiley & Sons Limited
The coexisting liquid compositions are given in Table 2.4 for each temperature reported by Vu [31].
Comparison of the two data sets is informative, but the Sanz et al. data should be corrected for the missing oligomers. Only approximate analysis can be performed from the published data. The oligomerization model equations can be used to convert the Sanz et al. data for comparison. The relation
A similar analysis can be performed on the data of Vu. Using Equation 2.10, the p values from the data range from 0.05 to 0.22. Analysis using
FIGURE 2.6 Parity plot of p values determined by two methods as explained in the text for data of Vu.
FIGURE 2.7 VLE data for lactic acid + water at 101.33 kPa as reported by Vu compared to the manipulated data of Sanz et al. Data of Vu are filled symbols with triangles for the vapor phase and squares for the liquid phase.
2.7 DENSITY OF AQUEOUS SOLUTIONS
Holten [28] fitted density data from Troupe et al. [32] using a third‐order polynomial with each wt% fitted separately. The individual fits represent the experimental data within 0.2%. To provide practitioners a more rapid calculation, we have refitted the data of Troupe et al. using Equation 2.26 where coefficients A and B are linear functions of the apparent wt% lactic acid, w. The calculated densities, ρ , match experimental data within 0.3% as shown in Figure 2.8.
(2.27)
2.8 VISCOSITY OF AQUEOUS SOLUTIONS
Troupe et al. [32] observed that the viscosity increased over time as did the titratable acidity when a 75 apparent wt% lactic acid sample was freshly prepared from 85 wt%. At room temperature, it took more the 20 days to reach equilibrium. Equilibration of solutions is critical to obtain reliable viscosity data, and equilibration is slow at 20°C. Suggested equilibration times are provided by Vu et al. [27]. Troupe et al. fitted their viscosity data with Equation 2.29 where each wt% was fitted separately. The individual fits represent the experiments within 5%. For practitioners, we provide a rapid way to interpolate the viscosity. We have regressed the coefficients A and B for the common log of viscosity