Poly(octadecyl methacrylate) via RAFT Technique and Its Rheological Study for Waxy Crude

The aim of our present work is to synthesize a comb-like polymeric pour point depressant (PPD), poly(octadecyl methacrylate) (POMA), using a reversible addition–fragmentation chain transfer (RAFT) polymerization technique, to improve the flowability of waxy crude oil. Analytical techniques such as FT-IR and NMR spectroscopy confirm the formation of POMA, while the molecular weights (MWs) were determined using the size exclusion chromatography (SEC) technique. Furthermore, viscosity and gelation point measurements were employed rheometrically to evaluate the efficiency of the synthesized polymer as a flow improver for waxy crude. The SEC results show that the number-average molecular weight (M_n) of the synthesized POMA increases linearly with conversion. The RAFT polymerization produces polymers with very narrow molecular weight distributions (MWDs) (1.19–1.35) as compared to that in conventional radical polymerization (MWD > 2). Under optimum conditions, the prepared polymer, POMA, reduced the gelation point of the crude oil by 4.1 °C at a 2000 ppm concentration. Furthermore, at a 2000 ppm concentration, the apparent viscosity of the crude oil is decreased from 379.71 mPa·s to 70.67 mPa·s at a temperature of 0 °C. Thus, the reduction in the apparent viscosity and gelation point signifies that the synthesized POMA acts as an effective polymeric additive for crude oil at low temperature.