A Drag Reducer: It’s Interaction with Water, Synthesis and Performance Evaluation

The interaction energy of three polymers with water was compared using molecular dynamics method. From the radial distribution functions it was found that the hydrogen bond between the oxygen atoms in the polymer molecules and the hydrogen atoms in the water molecules is mainly responsible for the interaction between the polymer and water. In laboratory experiments, which were done to verify the radial distribution functions, a ternary hydrophobic association polyacrylamide (P(AM-AA-MPEG)), which was a copolymer made from a nonionic surfactant hydrophobic monomer, acrylamide and acrylate, was used as a drag reducer. HNMR spectroscopy of the ternary hydrophobic association polyacrylamide molecules indicates that the copolymerization was successful. The molecular weight of the ternary hydrophobic association polyacrylamide measured with light scattering method is 2.83×10⁶ g/mol. The friction of fresh water flowing in a pipe was used as a blank friction data group to calculate the rate of drag reduction. The maximum rate of drag reduction at polyacrylamide (PAM) concentration of 0.025% is only 40%, while the maximum rate of drag reduction at P(AM-AA-MPEG) concentration of 0.025% can be as high as 65%. Polymers having higher interaction energy with water have better drag reduction performance. The network structure formed by the molecules of a polymer in water solution is the direct cause of drag reduction, the long side chains of a polymer also help improve the rate of drag reduction.