Gamma radiation-induced grafting of C₅ aliphatic petroleum resin onto ethylene-co-vinyl acetate copolymer for improving crude oil flowability

At present, ethylene-co-vinyl acetate (EVA) copolymers are the predominant choice among pour point depressants (PPDS) for enhancing the flowability of waxy crude oil. Still, they have shortcomings. Thus, this work aims to investigate the irradiation modification of a commercial EVA copolymer using C-5 aliphatic petroleum resin (C-5 PR) and its potential for utilization as a flow improver for crude oil. Results conclusively demonstrate the successful grafting of (C-5 PR) onto EVA copolymer through gamma radiation, confirmed via grafting parameter characterization, FTIR, and H-1 NMR spectroscopy. This modification significantly improved pour point results (Delta PPD = 24, 21, and 24 degrees C) for (EVA)(0kGy), (EVA)(50kGy), and (1EVA:1C(5) PR)(50kGy) when treated with 3000 ppm of additives. Notably, the grafted EVA copolymers with C-5 PR (1EVA:1C(5) PR)(50kGy) outperformed non-modified EVA at a lower dosage of 1000 ppm. Also, irradiating EVA copolymer without insertion C-5 PR resulted in EVA copolymer crosslinking, leading to a decrease in efficiency that could attributed to its accumulation. Furthermore, the crude oil's rheological properties were substantially enhanced, evidenced by viscosity reductions of 60.8%, 51.3%, and 64.1% at 25 degrees C, and 55.2%, 18.7%, and 59.4% at 12 degrees C with the addition of 1000 ppm. Increasing the dosage to 3000 ppm led to even more remarkable viscosity decreases: 76.2%, 67.7%, and 78.2% at 25 degrees C, and 83.2%, 74.9%, and 84.7% at 12 degrees C for (EVA)(0kGy), (EVA)(50kGy), and (1EVA:1C(5) PR)(50kGy), respectively.