引用本文:
刘迎, 魏荣卿, 刘晓宁, 万元松. L-丙交酯中乳酸含量的分析[J]. 应用化学,
2008, 25(9): 1104-1106.
Citation: LIU Ying, WEI Rong-Qing, LIU Xiao-Ning, WAN Yuan-Song. Analysis of Lactic Acid Content in L-Lactide[J]. Chinese Journal of Applied Chemistry, 2008, 25(9): 1104-1106.
Citation: LIU Ying, WEI Rong-Qing, LIU Xiao-Ning, WAN Yuan-Song. Analysis of Lactic Acid Content in L-Lactide[J]. Chinese Journal of Applied Chemistry, 2008, 25(9): 1104-1106.
L-丙交酯中乳酸含量的分析
摘要:
L-丙交酯中残留乳酸含量的分析有助于对丙交酯的纯度及后期应用的质量进行控制。在GB2023-2003中利用强酸返滴定法可测定乳酸的含量,但不适用于测定丙交酯的含量。采用文献报道的甲醇钠非水滴定法测定的乳酸酸值低于实际值,偏差较大。经对强酸返滴定法和甲醇钠非水滴定法的比较,确定了该偏差值为一恒定值,以此作为校正系数(P=1.228),通过"滴定-校正法"可以较方便准确的获得粗品L-丙交酯中的乳酸含量,从而获得重结晶过程对聚合级丙交酯纯化的质量控制。应用结果表明,随重结晶次数的增加,纯化晶体和滤液中的乳酸含量逐渐降低,当重结晶第3次后乳酸含量保持不变;当ω(乳酸)<1.0%时,丙交酯可达到聚合纯度的要求;当ω(乳酸)<0.4%时,聚合获得的聚乳酸分子量可达3×105。
English
Analysis of Lactic Acid Content in L-Lactide
Abstract:
Determination of lactic acid residue in L-lactide is necessary in controlling its purity and the quality in applications.In the presence of lactide,the method referred in GB2023-2003 to determine lactic acid content with back-titration by strong acid is improper;meanwhile the lactic acid content in lactide determined by sodium alkoxide titration reported previously appeared to be lower than the exact value.The two titration methods were correlated by a coefficent of P=1.228 and the method of quantitative determination of lactic acid in lactide by "titration-convert" was proposed.The result indicated the lactic acid content in lactide crystals and mother liquid decreased with recrystallization cycle.After 3 recrystallization cycles,the content of lactic acid was constant.The lactide met the requirement of polymerization with a lactic acid content of <1.0%,and polylactic acid with Mη up to 3×105 was obtained when the lactic acid content was <0.4%.
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Key words:
- L-lactide
- / lactic acid
- / the content of lactic acid
- / titration-convert
- / sodium alkoxide
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