| The polymer fracturing system obtained by physical crosslinking technology has excellent viscoelastic properties and shear resistance,so it has a broad application prospects as a new type of fracturing system.However,the fracturing system obtained by physical crosslinking technology is mainly focused on the hydrophobic association polymer fracturing system,about the use of solute through the electrostatic attraction between the molecules interact and form of the fracturing fluid is rarely reported.Therefore this study by physical crosslinking as a starting point,on the basis of the polyelectrolyte complexes and study the preparation of homogeneous viscous solution of polyelectrolyte complex conditions,the mechanism and properties of polyelectrolyte complex solution were studied,as well as its application as fracturing fluid for the study of the relevant performance.With a view to provide theoretical guidance for the preparation of homogeneous phase of polymer electrolyte composite solution system,to provide a new research direction for the preparation of physical crosslinking fracturing system.First of all,the cationic polyelectrolyte and anionic polyelectrolyte were prepared.This article choosed DMDAAC as cationic monomer,the synthesis of a series of different cationic degree and molecular weight of cationic polyelectrolyte CP;With acrylic acid(AA)as the anionic monomer synthesized by different degree of hydrolysis of anionic polyelectrolyte HPAM and anionic polyelectrolyte poly(sodium acrylate)of different molecular weights PAA.The above three kinds of polyelectrolyte charge density and molecular weight can be adjusted through the experimental requirements provides favorable conditions for the preparation of polymercomplex solution.Because HPAM and PAA polymers belong to weak polyelectrolyte,in order to further study the composite solution system.Combining the extensive experiment choosed the molecular weight of about 100000 strong polyelectrolyte polystyrene sulfonate(PSS)as anionic polyelectrolyte.Then,the polymer composite solution was prepared.Adjust the degree of hydrolysis of HPAM and cationic degree of CP successfully prepared homogeneous CP/HPAM polymer composite solution;By adjusting the cationic degree,molecular weight and the complex ratio,solution concentration of the four conditions,the successful preparation of the homogeneous viscous polymer composite solution system CP/PAA and CP/PSS.CP-g/PAA-1 and CP-g/PSS were identified as the research system.When the concentration of the cationic polymer solution is 0.5%(wt),CP-g/PAA-1 and CP-g/PSS composite solution viscosity of 264 mPa·s and the 240 mPa-s,respectively,which were 8.8 and 8 times of the single cationic polymer solution,showing good viscosifying effect.Finally,the related properties and mechanism of the polymer composite solution were studied.By dynamic light scattering and scanning electron microscopy(sem)analysis,verified the polymer composite solution system can achieve the goal of increasing viscosity is to form a network structure.The experimental results show that the effect of small molecule salt and pH value on the polymer composite solution can be attributed to the introduction of small molecular electrolytesshielding the effective charge of polyelectrolyte.The shielding effect causes the destruction of the polymer solution network structure and the molecular structure of polymer chain segment of crimp contraction.The experimental results show that the CP-g/PAA-1 and CP-g/PSS systems have good temperature resistance,and the temperature resistance of the two systems can reach 120? and 140?respectively;the two system have anti shearing ability and good viscoelasticity propertiesand quitetornglue.It is proved that it has potential application value as a new type of physical crosslinking fracturing system. |
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