A segmented polyurethane elastomer (PU) was synthesized in poly(lactic acid) (PLA) melt by reactive processing. The isocyanate component was anticipated to react with the end-groups of PLA resulting in the formation of block-copolymers. The stoichiometry of the functional groups was optimized in the preliminary experiments. Two different processing methods were compared in the further experiments: conventional mixing of PU with PLA (PLA/PU), and reactive blending (PLA-b-PU). The comparison of the structure and properties of compatibilized reactive blends and conventional physical blends clearly shows the benefits of reactive processing. Coupling resulted in a finer dispersion of the particles in the matrix leading to better mechanical properties in the reactive blend. The successful synthesis of PLA-b-PU block copolymers was confirmed by NMR spectroscopy. The isocyanate component was found to react only with the hydroxyl end-groups of PLA, while the formation of amide and acylurea groups was not detected on the carboxyl end.

中文翻译：

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通过反应性加工将聚乳酸与聚氨酯弹性体偶联

通过反应性加工在聚乳酸 (PLA) 熔体中合成了分段聚氨酯弹性体 (PU)。异氰酸酯组分预计会与 PLA 的端基反应，导致形成嵌段共聚物。在初步实验中优化了官能团的化学计量。在进一步的实验中比较了两种不同的加工方法：PU 与 PLA 的常规混合 (PLA/PU) 和反应性混合 (PLA-b-PU)。增容反应性共混物和传统物理共混物的结构和性能的比较清楚地显示了反应性加工的好处。偶联导致颗粒在基体中的更细分散，从而在反应性混合物中产生更好的机械性能。核磁共振谱证实了PLA-b-PU嵌段共聚物的成功合成。发现异氰酸酯组分仅与 PLA 的羟基端基反应，而在羧基端未检测到酰胺和酰脲基团的形成。