Synthesis of tetradecyl methacrylate and isopentenyl alcohol binary copolymers and their regulation on crystallization behavior and cold flow properties of diesel fuel

Wax crystallization and aggregation are the primary causes of poor cold flow properties of diesel. Polymethacrylates have been verified as highly efficient cold flow improvers (CFIs) for diesel, but their effectiveness is strongly influenced by the balance between wax compatible alkyl chains and polar functional groups. In this study, binary copolymers derived from tetradecyl methacrylate and isopentenyl alcohol (C 14 MC-IPOH) were synthesized. Tetradecyl alkyl segments are nonpolar units co-crystallizing with paraffin wax, while IPOH hydroxyl polar segments modify copolymer dispersion and interfacial interactions in diesel. This structure possesses the advantages of both polymeric CFIs and surfactants, thereby enhancing its regulating capacity on wax crystallization behaviors. To identify a suitable balance between the two structural units, the effects of monomer molar ratio and additive dosage on the cold filter plugging point (CFPP) and solid point (SP) of diesel were investigated. Response surface analysis showed that the best performance was obtained with a C 14 MC to IPOH molar ratio of 6:1 at a dosage of 2500 ppm, where the CFPP and SP were reduced by 16 °C and 18 °C, respectively. Finally, differential scanning calorimetry, rheological measurements, and polarized optical microscopy combined with quantitative image analysis were used to examine changes in wax crystallization, crystal size, morphology, and aggregation in untreated diesel and diesel treated with C 14 MC-IPOH. Based on these results, a possible mechanism by which the copolymer with surface active structural features regulates wax crystal growth and aggregation during cooling was proposed.