Effect of cashew nutshell liquid-modified EVAL on flow behavior and crystallization of waxy systems

ABSTRACT Light crude oils are being progressively depleted as the dominant primary energy source, leading to increased attention on the extraction and utilization of highly waxy crude oils. To address the poor low-temperature fluidity of waxy crude oil, cashew nut shell liquid (CNSL), which is rich in anacardic acid, was extracted from low-cost and renewable cashew nut shells and subsequently modified with EVAL through esterification at different mass ratios (mEVAL:mCNSL = 1:1, 1:2, 1:3) to synthesize the EVAL-g-AAC pour point depressant. Chemical structure characterization confirmed the successful grafting of EVAL with anacardic acid. The experimental results demonstrated that EVAL-g-AAC 2 (mEVAL:mCNSL = 1:2) exhibited the best pour point-reducing performance at a dosage of 400 ppm, lowering the pour point of waxy model oils by 24 °C. This reduction was 8 °C and 5 °C greater than that achieved by EVA and EVAL, respectively. In addition, its viscosity reduction rate increased by 28.5% relative to EVAL, while simultaneously decreasing the gelation temperature and viscoelastic properties of the model oils. Additionally, the low-temperature crystallization behavior of wax crystals was investigated using polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). It proposed a possible mechanism of action for the new pour point depressant through the “alkyl long-chain promotes co-crystallization formation, polar groups promote dispersion, and rigid structure promotes nucleation” triple synergy to improve the crystallization behavior of wax molecules.