Crystallization behavior of neat biodiesel and biodiesel treated with ozonized vegetable oil

The utilization of neat biodiesel is limited by its poor low‐temperature flow properties, which are mainly dictated by the lengths of the hydrocarbon chains and the presence of unsaturation. However, the pour point of neat biodiesel prepared from soybean oil, sunflower oil and rapeseed oil can be improved significantly by treatment with small amounts of ozonized vegetable oil. The presence of carbon‐carbon double bonds along the hydrocarbon chains is necessary to make ozonized vegetable oil an effective pour point depressant for fatty acid methyl esters (FAME). Differential scanning calorimetry and polarized light microscopy revealed that ozonized vegetable oil affects both nucleation and crystal growth of FAME and biodiesel. Treatment of biodiesel with ozonized vegetable oil leads to the formation of considerably smaller, but more numerous crystals at subzero temperatures.