Synthesis and evaluation of alkyl acrylate-vinyl acetate-maleic anhydride terpolymers as cold flow improvers for diesel fuel

Four different alkyl chain length of n-alkyl acrylate-vinyl acetate-maleic anhydride terpolymers were synthesized by radical polymerization and characterized by FTIR and GPC. To further the development of these cold flow improvers, their performance mechanism was studied. The carbon number distribution of n-alkanes in 0# diesel fuel was analyzed by GC. The rheological behavior and crystallization behavior of diesel fuel treated with and without additives were studied using an advanced rheometer and an optical microscope. The results show that the influence of alkyl chain length of terpolymer was closely related to the content of the corresponding n-alkane in the diesel fuel. Besides, the formation of three-dimensional network directly determines the solidifying point of diesel fuel, while the cold filter plugging point is closely related to the size, shape and aggregation of wax crystals, thus the effects of cold flow improver on the solidifying point and cold filter plugging point of diesel fuel are sometimes inconsistent. Moreover, a good diesel cold flow improver should be detrimental to the formation of three-dimensional network and detrimental to the formation of too large wax crystals or wax crystals tending to form large clusters.