水性聚氨酯/明胶共聚物的制备及表征

Preparation and Characterization of Water-based Polyurethane/Gelatin Copolymers

以二羟甲基丙酸(DMPA)作为亲水单体,采用甲苯二异氰酸酯(TDI)、聚酯二元醇(PCDL)为原料,于水性介质中在偶联剂水杨醛的作用下,制备了聚氨酯/明胶共聚物,用傅里叶变换红外光谱(FTIR)分析及凝胶渗透色谱分析(GPC)证实了该共聚反应的发生;研究结果表明,DMPA质量分数为5%时,可得到稳定的聚氨酯乳液,此时胶膜的吸水率为8.52%;热重分析(TGA)显示,共聚物胶膜在240℃开始分解;示差扫描量热分析(DSC)显示,经改性后共聚物的玻璃化温度(Tg)为66℃;X射线衍射分析(XRD)表明,聚氨酯的加入使共聚物胶膜的结晶度大大降低,在聚氨酯质量分数为50%时,共聚物的结晶度降为2%;力学性能分析及耐水性测试表明,当聚氨酯质量分数从0%到50%变化时,胶膜的抗张强度由83 MPa下降到37.3 MPa,断裂伸长率从25.5%增大到325.6%,当聚氨酯质量分数从10%到50%变化时,胶膜的吸水率从251%下降到65%。

The present work presents a study on the grafting of polyurethane onto chitosan in aqueous media. The effect of the amount of hydrophilic monomer on the water resistance of polyurethane was observed. Characterization of graft copolymers was performed by fourier transform infrared spectroscopy （ FTIR ）, gel permeation chromatography （ GPC ）, thermogravimetric＇analysis （ TGA ）, differential scanning calorimetry （ DSC ）, X-ray diffraction analysis （ XRD）, mechanical properties testing, and water resistance testing. TGA tests reveal that the thermal decomposition temperature of the copolymers increased significantly, being 34 ℃ higher than that of pure gelatin,while DSC measurements indicate that the glass transition temperature decreased with the introduction of polyurethane. Accordingly, the mechanical and anti-water absorption properties also proved to be enhanced greatly as evidenced by mechanical test and water absorptions data in which the copolymers containing 50% of polyurethane have highest elongation at break （325.6 % ）, and lowest water absorption capacity （65 % ）.