摘要
为研究生物柴油的低温流动性,构建了6种用于模拟常见植物油生物柴油的含21条链和4种十八酸甲酯的模型。利用正则系综和COMPASS力场,对模型进行了不同温度下的分子动力学研究。计算了不同温度下模拟系统的热容和碳原子自扩散系数,得到两者随温度显著变化的区间交集。模拟发现,该交集和系统的冷滤点几乎一致,证明了本模拟模型和方法的可行性。对冷滤点前后系统的微观结构变化进行了观察,发现当温度降至冷滤点以下时,分子链趋于伸展,且局部排列更为有序,这与冷滤点的定义及热力学的熵原理是一致的。
Six models of common vegetable oil biodiesel were constructed . Each contains 21 chains and four kinds of methyl octadecanate to study their low temperature fluidity. Molecular dynamics （MD） simulation was carried out at different temperatures in NVT ensemble and by COMPASS force field. Heat capacities and self--diffusion constants of each system at different temperatures were calculated, and the interval intersection of both significant changes with the simulation temperature was then achieved. It was found that the intersection of each system was consistent with its Cold Filter Plugging Point （CFPP）, which proved that the model and method mentioned here is feasible for the entitled study. The investigation on the microstructures of different temperatures before and after CFPP revealed that when the temperature drops to the CFPP below, molecular chains tend to be coordinated and extended, and local arrangement is more orderly, which is consistent with the definition of the CFPP and the fundamental of entropy-decrease.
出处
《常州大学学报（自然科学版）》
CAS
2012年第2期88-92,共5页
Journal of Changzhou University：Natural Science Edition
关键词
分子动力学
模拟生物柴油系统
冷滤点
微观结构
Molecular dynamics （MD）
simulation system of biological diesel
CFPP
the microstructures
