中文摘要：

生物柴油低温流动性的研究主要集中在低温流动性的影响因素及改进方法等方面,对低温下蜡晶的结晶行为鲜有报道,而蜡晶的析出对其低温流动性的影响至关重要.本研究以不同原料的生物柴油为对象,利用气相色谱仪对其组成进行了分析;通过差示扫描量热法（DSC）对析蜡点进行了研究,根据DSC曲线给出了计算不同温度下析蜡量的方法并根据该方法对不同温度下的析蜡量进行了测定.DSC计算结果与高速离心分离法的测量结果进行了对比,验证了DSC法的可靠性.生物柴油的DSC曲线主要由2个峰组成,高温区间的峰对应于饱和脂肪酸甲酯的析出,低温区间的峰对应于不饱和脂肪酸甲酯的析出.生物柴油中饱和脂肪酸甲酯的含量越多,析蜡点及不同温度下的析蜡量越高.

英文摘要：

The study on low temperature fluidity of biodiesel has mainly focused on the factors affecting low tem- perature fluidity and improvement methods. However, the crystallization behavior of wax at low temperature has been hardly reported while it is crucial for the cold flow properties. By taking the different raw materials of biodiesel as re- search object, the composition of biodiesel have been analyzed by gas chromatography, the wax appearance tempera- ture （WAT） and the amount of wax precipitated at different temperature of biodiesels have been studied by differenti- al scanning calorimetry （DSC） according to the method described in the paper. The amount of precipitated wax at different temperatures determined by DSC was compared with the results obtained by high speed centrifugation; the reliability of DSC method was verified. The DSC curves of biodiesel were mainly composed of two peaks; the high temperature peak was corresponding to the precipitation of saturated aliphatic acid methyl ester and the low one was corresponding to the precipitation of unsaturated aliphatic acid methyl ester. The content of saturated aliphatic acid methyl ester of biodiesel was more, and the values of WAT and amount of wax precipitated at different temperatures were higher as well.