A Drag Reducer: It’s Interaction with Water, Synthesis and Performance Evaluation
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摘要: 以分子动力学方法对比了3种聚合物与水的相互作用能,由径向分布函数得到,聚合物中氧原子与水中氢原子形成的氢键是聚合物与水作用的主要来源。验证实验中以一种非离子表面活性剂型疏水单体与丙烯酰胺、丙烯酸共聚得到一种阴离子型三元疏水缔合聚丙烯酰胺作为降阻剂,核磁氢谱证明合成是成功的,光散射法测得三元聚合物分子量为2.83×106 g/mol。以清水在管道中流动的摩阻为空白组,计算降阻率。在聚合物加量0.025%条件下,PAM的降阻率最高仅达到40%,P(AM-AA-MPEG)的降阻率可达65%。与水相互作用能强的聚合物,降阻性能越好,聚合物在水中形成网状结构是降阻的直接原因,聚合物的长侧链也能提高降阻率。Abstract: 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.
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