聚乳酸和乳酸-乙醇酸共聚物的溶液热力学

Solution thermodynamics of poly (lactic acid) and poly (lactic acid-co-glycolic acid)

为了准确地预测溶液热力学数据,分别使用了36和38种溶剂对聚乳酸和乳酸-乙醇酸共聚物进行实验研究。采用正交优化计算方法确定了聚乳酸和乳酸-乙醇酸共聚物的三维溶度参数,分别为:δ_d=17. 969 (MPa)^(1/2),δ_p=6. 707 (MPa)^(1/2),δ_h=7. 324(MPa)^(1/2);δ_d=17. 083 (MPa)^(1/2),δ_p=6. 939 (MPa)^(1/2),δ_h=8. 650 (MPa)^(1/2)。单体中乳酸和乙醇酸浓度的升高会引起高分子聚合物溶度参数的增大。依据溶度参数,计算了聚乳酸和乳酸-乙醇酸共聚物与溶剂间的相互作用参数和相互作用半径。同时,计算了聚乳酸和乳酸-乙醇酸共聚物溶剂的体积修正系数,聚乳酸—溶剂体系和乳酸乙醇酸共聚物—溶剂体系的体积修正系数分别在0. 80～0. 90和0. 85～1. 10范围内。获得的相互作用参数、相互作用半径及体积校正系数完全符合Flory-Huggins高分子溶液理论。

In order to accurately predict the thermodynamic data,36 and 38 kinds of solvents were used for poly(lactic acid)and poly(lactic acid-co-glycolic acid),respectively.An optimization calculation method was used to determine solubility parameters.The solubility parameters of poly(lactic acid)areδd=17.969(MPa)1/2,δp=6.707(MPa)1/2,δh=7.324(MPa)1/2 and that of poly(lactic acid-co-glycolic acid)areδd=17.083(MPa)1/2,δp=6.939(MPa)1/2,δh=8.650(MPa)1/2.The solubility parameter increases with increasement of the monomer content.Based on the solubility parameters of poly(lactic acid)and poly(lactic acid-co-glycolic acid),the interaction parameters and the interaction radii between them and their solvents have been calculated.The volume correction constants of the Hansen relationship were also calculated for poly(lactic acid)and poly(lactic acid-co-glycolic acid)firstly.The volume correction constants are in 0.80~0.90 for poly(lactic acid)-solvent system and in 0.85~1.10 for poly(lactic acid-co-glycolic acid)-solvent system.The interaction parameters,interaction radii and the volume correction constants are completely consistent with Flory-Huggins theory.