木质素多元醇的制备及表征

Preparation and characterization of lignin polyols

以木质素为原料,小分子醇混合物为液化剂、浓磷酸为催化剂,制备了木质素多元醇。考察了液化剂配比、液固比(液化剂与木质素质量比)、反应温度等条件对液化率的影响。确定了制备木质素多元醇的最佳工艺:液化剂1,2-丙二醇和丙三醇质量比5∶5,液固比13∶1,反应温度170℃,此条件下液化率可达99.69%。最佳工艺条件下制备的木质素多元醇羟值为2 213.74 mg/g,酸值为40.07 mg/g,黏度为947 mPa·s。红外光谱及扫描电镜分析其结构与性能结果表明,液化过程中木质素发生降解。流变性能分析结果表明,木质素多元醇表现出切力变稀的现象。

Lignin polyols were prepared using lignin as raw material,a mixture of small molecule alcohols as liquefaction agent,and concentrated phosphoric acid as catalyst.The influences of liquefaction agent ratio,liquid solid ratio(mass ratio of liquefaction agent to lignin),reaction temperature on liquefaction rate were investigated.The optimal process for preparing lignin polyols has been determined as follow:the mass ratio of liquefied agent 1,2-propanediol to glycerol of 5∶5,the liquid-solid ratio of 13∶1,the reaction temperature of 170℃,and the liquefaction rate could reach 99.69%.Under the optimal conditions,the hydroxyl value,acid value and viscosity of lignin polyol were 2213.74 mg/g,40.07 mg/g and 947 mPa·s,respectively.The structure and properties detected by infrared spectroscopy and SEM showed that lignin was degraded during the liquefaction process.The rheological performance analysis results indicated that lignin polyols exhibited a phenomenon of shear thinning.