Study on the relationship between the structure and activities of alkyl methacrylate–maleic anhydride polymers as cold flow improvers in diesel fuels

In order to find efficient cold flow improvers for diesel fuels derived from crude oil, copolymers (R1MC–MA) were prepared making use of the copolymerization of methacrylate (R1MC) of various alkyls with maleic anhydride (MA), and terpolymers (R1MC–MA–R2MC) were prepared by the reaction of long-chain alkyl methacrylate (R1MC), maleic anhydride (MA), and short alkyl methacrylate (R2MC). The additives were purified and characterized by IR, 1H–NMR, and GPC. The activities of the synthetic products as the cold flow improvers in two diesel fuels were investigated. The results indicate that: (1) the alkyl chain length of R1 in R1MC–MA copolymers significantly affects the solid point depressing performance. When the long-chain alkyl R1 is n–C14H29– and the reaction material molar ratio (R1MC/MA) is 1:2, the C14MC–2MA possesses the best ΔSP property; (2) the (C14MC–MA–R2MC) terpolymers all demonstrate excellent solid point depression properties when the short-chain alkyl R2 varies from CH3– to n–C8H17–; (3) however, all of the tested copolymers and terpolymers do not demonstrate necessary cold filter plugging point depression performance.