木质素基聚乳酸复合膜的物理老化性能研究

Study on Physical Aging Properties of Lignin-based Polylactic Acid Composite Films

关键词:  木质素  酯化反应  聚乳酸  增韧  结晶度  物理老化

Key Words:lignin  esterification reaction  polylactic acid  toughening  crystallinity degree  physical aging

摘要:本研究合成了3种基于辛酰氯、十二酰氯和十八酰氯酯化改性的木质素酯（LEs），并将其用于聚乳酸（PLA）的复合增韧改性。通过溶剂浇铸法制备了LEs/PLA复合膜，系统研究了不同LEs及不同添加量对LEs/PLA复合膜力学性能的影响以及物理老化过程中力学性能的变化特性。结果表明，物理老化时间的延长会显著降低复合膜样品的断裂伸长率，并提高其拉伸强度。但LEs/PLA复合膜的断裂伸长率老化后仍高于同老化条件下纯PLA，添加质量分数10%木质素十八烷基酯（LE18）的复合膜经84天物理老化后断裂伸长率仍有30.7%，为同老化条件下纯PLA断裂伸长率的6.27倍，拉伸强度为42.1 MPa。

Abstract:Three kinds of lignin esters （LEs） based on octyl chloride， dodecyl chloride and stearyl chloride were synthesized for the compound toughening modification of polylactic acid （PLA）. LEs/PLA composite films were prepared by solvent casting method. The effects of different types and dosages of LEs on the changes of mechanical properties of LEs/PLA composite films during the physical aging process were systematically studied. The results showed that the extension of physical aging time could significantly reduce the elongation at break and improve the tensile strength of the composite film. However， the elongation at break of the composite film with LEs added was still higher than that of pure PLA after aging. The elongation at break of the composite film with LE18 added with a mass fraction of 10% after 84 days of physical aging was still 30.7%， which was 6.27 times of that of pure PLA under the same condition， and the tensile strength was 42.1 MPa.