Terpene resin prepared from renewable turpentine oil as a new type of cold flow improver for soybean biodiesel-diesel blends

The widespread use of biodiesel-diesel blends in society is one of the main ways to alleviate the global petrochemical energy shortage. Cold flow improvers (CFIs) can effectively improve the cold flow properties of biodiesel-diesel blends. Traditional CFIs are specific types of polymers synthesized from petrochemical products such as polymethacrylate, ethylene-vinyl acetate and poly alpha-olefin. To reduce the dependence on these non-renewable resources, terpene resin synthesized from renewable turpentine is used as a new type of CFI for biodiesel-diesel blends, and the effects of terpene resin on improving the cold flow properties of biodiesel-diesel blends are studied for the first time. The results indicate that the depression effects are extensively affected by the molecular weight of terpene resin, their addition amount and volume ratio of diesel and biodiesel in the blends. The terpene resin with an average molecular weight of 1212 presents the best depressive effect at the addition of 2000 ppm, and the cold filter plugging point (CFPP) of B30 (30 vol%. biodiesel + 70 vol%. diesel) decreases by 10 °C. Furthermore, using a differential scanning calorimeter, polarization optical microscope and rheological analysis, the paraffin crystallisation and morphology of wax crystals for diesel biodiesel-diesel blends before and after treatment with terpene resin are studied, and the mechanism of improving cold flow properties is discussed.