聚乳酸二醇及其聚氨酯的合成及性能研究

Synthesis and Properties of Bio-based Polyurethane Based on Polylactide Diol

以左旋乳酸(L-LA)单体为原料,分别与1,4-丁二醇(BDO)、1,6-己二醇(HDO)、1,12-十二烷二醇(DCO)进行酯化反应,合成了分子量约为1500 g/mol的聚乳酸二醇。通过傅里叶变换红外光谱(FT-IR)和核磁共振(1H-NMR)测试分析了聚乳酸二醇的结构,并采用自动电位滴定仪测定了羟值及酸值。以聚乳酸二醇为软段,六亚甲基二异氰酸酯(HDI)和扩链剂BDO为硬段,采用溶液法合成了一系列聚乳酸聚氨酯,并采用FT-IR、凝胶渗透色谱、差示扫描量热仪、热重分析以及拉伸测试等对聚氨酯的结构与性能进行表征。结果表明,随着合成聚乳酸二醇所用的3种亚烷基二醇碳链长度的增加,聚乳酸聚氨酯材料的熔点从118℃降低到103℃,玻璃化转变温度从8℃降低到-8℃,断裂伸长率从154%增加到211%,其拉伸强度(在8 MPa左右)、模量和邵A硬度逐渐减小。

Ploylactate(PLA)diols with Mw 1500 were synthesized by esterification using lactic acid(L-LA)as monomer,reacting with 1,4-butanediol(BDO),1,6-hexanediol(HDO)and 1,12-dodecanediol(DCO)respectively.The structure of PLA diols were analyzed by Fourier transform infrared spectroscopy(FT-IR)and nuclear magnetic resonance(1H-NMR).The hydroxyl and acid values were determined by automatic potentiometric titrator.A series of polylactate polyurethanes were synthesized by solution method using PLA diol as soft segment,hexamethylene diisocyanate(HDI)and chain extender BDO as hard segment.The structure and properties of the polyurethanes were characterized by FT-IR,gel permeation chromatography(GPC),differential scanning calorimetry(DSC),thermogravimetric analysis(TG)and tensile test.The results showed that,with the increase of the carbon chain length of the three alkylene diols used in the synthesis of PLA diol,the melting point of polylactate polyurethane decreased from 118℃ to 103℃,the glass transition temperature decreased from 8℃ to -8℃,the elongation at break increased from 154% to 211%.The tensile strength(around 8 MPa),modulus and Shore hardness of the polylactate polyurethane gradually decreased.