Preparation of EVAM-g-NCACQDs nanocomposite pour point depressant and its effect on rheological properties of model waxy oil

In this paper, amino carbon quantum dots (NCACQDs) were synthesized from aspartic acid and citric acid by pyrolysis method, and the nanocomposite pour point depressant EVAM-g-NCACQDs was prepared by grafting NCACQDs with modified ethylene vinyl acetate copolymer (EVAM) by solution method. The improvement effect and mechanism of EVAM-g-NCACQDs on the low-temperature fluidity of wax oils were investigated by combining the evaluation methods of pour point determination, rheological analysis, and polarized light microscopy. The experimental results showed that when the doping amount of NCACQDs was 0.5 wt% of the mass of EVAM, the addition of 500 ppm of EVAM-g-NCACQDs could reduce the pour point of the wax oil from 34 °C to 11 °C, and the viscosity of the wax oil was only 48 mPa·s at 20 °C, which further reduced the pour point of the wax oil by 8 °C compared to that of the wax oil added with the same dosage of EVAM, and the viscosity was reduced by 94.27%.Polarized light microscopy showed that the wax crystals with EVAM-g-NCACQDs formed a regular and tight petal structure with clearer boundaries and homogeneous dispersion, which allowed the oil-phase flow space to be fully released at low temperatures, thus significantly improving the low-temperature fluidity of the wax oils.