Study on structure control and pour point depression mechanism of comb-type copolymers

A series of poly (n-alkyl acrylate-maleic anhydride) with different molecular weights were prepared as pour point depressants (PPDs) for JENM waxy crude oil obtained from the China-Myanmar crude oil pipeline. The crystallization temperature, wax morphology, and rheological behavior of crude oil were analyzed by differential scanning calorimetry, polarizing microscope, and rotary rheometer, respectively. The results indicate that the molecular weight significantly affects the performance of the pour point depressant. When the weight-average molecular weight (Mw) of copolymers were ranging from 60,000 to 70,000, it has a better pour point depression effect for JENM crude oil. The added copolymer (MW = 68,300) has achieved optimal performance which decreased the pour point of crude oil from 30 to 19 °C and crystallization temperature from 39.5 to 36.1 °C with the smallest wax crystal size and the 96.7% reduction viscosity.