沙柳多元醇液化产物流变性能的研究

沙柳木粉在液化剂和催化剂的作用下制成的液化产物可生产制作聚氨酯、环氧树脂、胶黏剂等。研究沙柳液化产物的流变性能,可探索宏观流变性质与液体微观内部反应机理之间的关系,优化设备结构和加工工艺条件,对其高效利用有着重大意义。本试验将沙柳木粉在浓硫酸催化条件下进行多元醇液化,通过改变液化处理条件(反应时间、反应温度和催化剂用量)制备具有不同流变性能的沙柳液化产物。利用旋转型流变仪对所制备的沙柳液化产物进行流变性能测试和分析。沙柳木粉液化条件的单因素试验和正交试验分析结果表明:影响沙柳液化产物黏度的主要因素是反应时间,其次是反应温度和催化剂用量,最佳工艺条件为反应时间70 min、反应温度170℃、催化剂用量5%。在最佳工艺条件下,剪切速率为78.87 s-1时,黏度为0.26 Pa·s。红外光谱(FT-IR)分析得出,液化物中纤维素被大量降解,半纤维素和木质素部分降解,羟基增加,生成更多的反应活性官能团,此条件下液化反应更加充分,流体黏度较大。流变性能测试结果显示:稳态扫描测试时,黏度随剪切速率的增加逐渐减小,表现出剪切变稀的现象;剪切应力随着剪切速率的增加逐渐升高,表现出假塑性流体的性质。通过动态频率扫描曲线变化规律分析,储能模量和损耗模量随着角频率的升高而逐渐增加,复数黏度却随之减小。

The research of rheological properties of salix polyol liquefied products

A liquefied product was fabricated by adding liquefaction agent and catalyst to salix powder.Salix liquefaction products can be converted into polyurethane,epoxy resin,adhesives,etc.The study of the rheological properties of salix liquefied products can explore the relationship between the macroscopic rheological properties and the liquid microscopic reaction mechanism,optimize the equipment structure and processing conditions,and play a significant role in the subsequent efficient use.In this test,the salix powder and the polyhydric alcohol were mixed,and the catalyst was added with concentrated sulfuric acid to prepare the salix liquefied product.In the salix liquefaction test,the degree of liquefaction was mainly affected by three factors,which were the reaction time,the reaction temperature,and the amount of catalyst.In the experiment,these three factors were used as variables,and the value of the variables was controlled within a certain range by a single factor method.At the same time,the main values that affect the degree of response were within this range.Because of the change of reaction conditions,the liquefied products prepared by this method had different rheological properties.The rheology test and analysis of the liquefied products of salix were carried out by a rotary rheometer.The single factor and orthogonal experiments were carried out on the liquefaction process of salix.The reaction time was the major factor affecting the liquefaction of salix,followed by the reaction temperature and the amount of catalyst.The optimum process conditions were the reaction time of 70 min,the reaction temperature of 170℃and the catalyst dosage of 5%.Under the optimum process conditions,the viscosity was about 0.26 Pa·s when the shear rate was about 78.87 s-1.The FT-IR analysis showed that the cellulose in the liquefied material was degraded in a large amount,the hemicellulose and lignin were partially degraded,and the hydroxyl group was increased to generate more reactive functional groups.Under this condition,the liquefaction reaction was more sufficient,and the fluid viscosity was larger.The shear stress increased with the increase of shear rate,showing the properties of pseudoplastic fluid.Through the analysis of the variation law of the dynamic frequency sweep curve,the storage modulus and the loss modulus increased with the increase of the angular frequency,and the complex viscosity decreased.