木质素聚氨酯薄膜合成条件及性能的研究

以麦草碱木质素、相对分子质量为300和 1000 的聚乙二醇(PEG)及多苯基甲烷多异氰酸酯(PAPI)为原料,以N,N-二甲基甲酰胺为溶剂,使用溶液浇注法固化成型工艺,制备了碱木质素聚氨酯薄膜。通过调整PEG1000与PEG300的比例提高了聚氨酯的力学性能。测定了木质素聚氨酯薄膜的弹性模量、拉伸强度和断裂拉伸率、耐撕裂度。实验结果表明,调节不同相对分子质量聚乙二醇在反应体系中的比例,可以显著提高成膜后的耐撕裂性能,改善由于加入木质素后聚氨酯薄膜过脆的缺点。当使用PEG1000与PEG300物质的量之比值为2.0,异氰酸酯指数为2.5,木质素加入量为 20%(质量分数)时,聚氨酯薄膜的弹性模量为 1.49 GPa、拉伸强度为 36.5 MPa、断裂拉伸率为 12.7%,耐撕裂度为 8460 mN,且成膜性能良好。

Synthetic Conditions and Performance of Lignin Based Polyurethane Film

The lignin-based polyurethane (PU) films were prepared from wheat straw alkali lignin by solution casting with polyethylene glycol (PEG) 300 or 1000 and polymeric phenyl methane-diisocyanate (PAPI) in the solvent of N,N-dimethylformamide (DMF). The mechanical performance of PU films was improved by adjusting the ratios of PEG 300 to PEG 1000. The mechanical performance including Young's modulus, tensile strength, elongation at break and tear resistance were tested for PU films. The results showed that by the way of altering the molar ratio of PEGs of different molecular weight in the system of reaction, the tear resistance behavior of PU films was outstandingly enhanced. Under the following conditions: NCO:OH=2.5, lignin coutent 20% and PEG 1000:PEG 300=2.0, the Young's modulus, tensile strength, elongation at break and tear resis-tance of PU film were 1.49 GPa, 36.5 MPa, 12.7% and 8460 mN, respectively, Meanwhile, its moulding film performance was better under the above conditions.