几种生物柴油的制备及其流变学性能的比较

以六种常见的动植物油脂为原料，制备生物柴油并测定其脂肪酸甲酯分布、凝点和冷滤点值。以动态流变仪为主要研究手段，研究了六种生物柴油的流体性能及相关影响因素。结果表明，生物柴油的凝点和冷滤点值受其脂肪酸甲酯分布的影响，饱和脂肪酸甲酯含量高的生物柴油，其凝点和冷滤点值也相应较高。流变学测定实验表明，六种生物柴油样品的流体性能受温度和剪切速率的影响。在较低的剪切速率范围内表现为典型的非牛顿流体行为，而在较高的剪切速率下则表现为牛顿流体行为。当流体温度高于生物柴油的相变温度时，六种生物柴油的表观黏度无明显差别，说明在该温度条件下生物柴油的脂肪酸甲酯分布对其流体黏度值影响不大；当流体温度接近其相变温度时，生物柴油流体黏度出现突跃式升高且其突变温度高于其冷滤点温度。

Preparation of several bio-diesels and analysis of their rheological behavior

Six kinds of bio-diesels were prepared with different oil materials, and some important characteristics such as the fatty acid composition, solidifying point and pour point were determined. The rheological properties and influencing factor of bio-diesels were studied systematically with AR-500 rheometers. The results show that the solidifying point and pour point of bio-diesel are affected by the fatty acid composition. The rheological data indicate that the bio diesels display a non newtonian flow shear-thinning behavior at low shear rate, and the rheological behaviors are influenced by temperature and shear rate. There is little difference in viscosity for bio-diesels when the temperature is higher than the phase change temperature of bio diesel. It is suggested that the fatty acid composition of bio diesel has no notable influence on viscosity. When the temperature is close to the phase change temperature, the viscosity of bio-diesel will increase greatly and the temperature is higher than the pour point of bio diesel.