Poly(lactic acid). Группа авторов

2.30 and 2.31. These correlations are compared with experimental data in Figures 2.9 and 2.10. The equations are within 10% except for the most concentrated measurement at 25°C where the error is 12%. For Equations 2.30 and 2.31, w is apparent wt% lactic acid (Figures 2.9 and 2.10).

FIGURE 2.8 Comparison of aqueous lactic acid density calculated using Equations 2.26–2.28 with experimental data of Troupe et al. as a function of apparent wt% and temperature.

(2.29)

(2.30)

(2.31)

FIGURE 2.9 Comparison of viscosity calculated using Equations 2.29–2.31 with experimental data of Troupe et al. as a function of temperature and apparent wt%.

FIGURE 2.10 Comparison of viscosity calculated using Equations 2.29–2.31 with experimental data of Troupe et al.

2.9 SUMMARY

      Vapor pressure measurements of anhydrous lactic acid could potentially be affected by oligomerization which produces water. Many vapor pressure measurements are provided by investigators measuring vapor pressure during use of lactic acid in chemical synthesis. Oligomerization of aqueous lactic acid significantly influences optical rotation, bubble temperature, and viscosity. Property measurements of aqueous solutions require careful validation of oligomer equilibration. The titratable acidities of equilibrated aqueous solutions are well represented by the Flory‐Schulz distribution which is a measure of the number of free acid groups in the equilibrated mixture.

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