Polyacrylamide will expire?
    In polymer processing is not well controlled laboratory or field conditions, stability of the solution the problem is complicated. Because the solution may be exposed to high temperatures for several weeks or months, viscosity loss serious. Three oil field application is so. Especially the high molecular weight polymer, its molecular weight and viscosity will stress such as high speed stirring and under the action of ultrasonic wave is reduced at high shear.
    Like other water soluble polymer, polyacrylamide aqueous solution stability in storage within days or weeks, its viscosity is more and more small. Have put forward many reasons to illustrate the independent and chain breaking the initial viscosity loss, which seems to be the most reasonable explanation is, decrease viscosity of fluid mechanics is become smaller due to changes caused by chain conformation of the. New dissolved polymer containing lump, the lump structure is composed of intra molecular hydrogen bond bound form a rigid chain segment ring structure and screw structure, is stable. But due to the entropy function, make the slow dissociation and formation of hydrogen bonds again, make the big molecule become soft, the coil becomes smaller, hydrodynamic volume and viscosity is smaller. This will reduce the efficiency of the use of it. Careful control of conditions in the manufacturing and transportation, homopolymer and placed in a temperature of 50 DEG C or less, without significant loss of molecular weight, the viscosity decreased phenomenon is not obvious. Microbiological stability of polyacrylamide solution whether consumption of the PAM in the solution is still a lack of sufficient evidence. But the microbes are often grown in solution, especially when the solution is pollution, will be made of transparent feculence at first, and even the emergence of precipitation. The molecular weight of more than 1.5 X 106, at 75 DEG C or higher storage temperature, lower viscosity loss and molecular weight will occur at the same time.