Preparation and evaluation of poly(octadecyl acrylate-methylbutenol) as a pour point depressant for waxy oil

Background Waxy crude oil is widely distributed worldwide and is an important fossil energy resource. Polyoctadecyl acrylate (POA) is a commonly used pour point depressant for waxy crude oil. Methods The introduction of polar groups is a novel and effective way to improve the performance of polymeric pour point depressants. Based on the solution radical polymerization reaction, this study successfully synthesized copolymer pour point depressants with different monomer ratios of poly(octadecyl acrylate-methylbutenol) (POAM) for the first time. Significant Findings The results indicate that among all the synthesized copolymer pour point depressants, the best performance is achieved when the molar ratio of octadecyl acrylate to methylbutenol is 3:1 (POAM-2). The addition of POAM-2 pour point depressant not only lowered the viscosity of the oil sample but also resulted in a decrease of 19 °C in the pour point, 7.3 °C in the gelation point, and the wax appearance temperature of the oil sample decreased by 4.1 °C. Microscopic images confirm that the POAM-2 changes the morphology of wax crystals from large plates to spherical shapes. The wax crystals also become denser, thereby inhibiting the formation of a network structure and further improving the rheological properties of the model waxy oil.