聚丙烯酰胺及其共聚物水溶液拉伸流变行为研究

Extension rheology behaviors of polyacrylamide and its copolymer in aqueous solution

拉伸黏度是决定聚合物驱替液驱油效率最重要的参数之一。采用CaBER1型拉伸流变仪和RS600流变仪测定了聚丙烯酰胺及其共聚物的拉伸黏度和流变行为,研究了聚合物的链结构对其溶液的拉伸黏度和流变行为的影响。结果表明,聚合物溶液的拉伸黏度要比相同应变速率条件下的剪切黏度高3个数量级以上,并且随着应变增加而增加、应变速率的增加而减小。在相同浓度时具有梳形结构的聚丙烯酰胺共聚物的拉伸黏度要远大于部分水解聚丙烯酰胺均聚物的拉伸黏度;在相同剪切黏度条件下,前者的拉伸黏度是后者的3～5倍,弹性模量相差1.8倍。随着浓度的增加,二者的拉伸黏度均显著增加。

Extension viscosity is one of the important parameters for the efficiency of polymer flooding. By means of CaBER1 extensional rheometer and RS 600 rheometer,the extension viscosity and rheological behaviors of polyacrylamide and its copolymer in aqueous solution were measured and the effect of polymer chain structures upon the extension viscosity and rheologic behaviors was studied. It has been found that the extension viscosity of polymer solution is greater than the shear viscosity of polymer solution at the same strain rate by three orders of magnitude or more,and it increases with the increase of strain but decreases with the increase of the strain rate. The extension viscosity of the comb-shaped polyacrylamide copolymer is much greater than that of the partially-hydrolyzed polyacrylamide homopolymer in case of the same concentration. In particular,the extension viscosity of the polyacrylamide copolymer solution is three to five times greater than that of the homopolymer solution on condition that they have the same shear viscosity,and the elastic model of the copolymer solution is 1.8 times greater than that of the homopolymer solution. The extension viscosity of both polyacrylamide and its copolymer in solution increases swiftly as the concentration of polymers in solution increases.