Study On Dispersion Polymerization And Copolymer Structure Of Cationic Polyacrylamide (PAM-DMC)

Cationic polyacrylamide is widely used in papermaking,water treatment,oil extraction,chemical technology and other aspects,and its different preparation methods and studies on the structure of copolymers have become a hot topic in academic circles.In this paper,high molecular weight cationic copolymer was prepared by dispersion polymerization.Under the action of special dispersant,a water-in-water cationic polyacrylamide emulsion with high molecular weight and cationic degree was formed.It is micellar in water,forming macromolecular emulsion with small and stable particle size.When used,it can be dispersed with water to form macromolecular mucus.In the oil field,polymers can be employed in the main components of thickeners,drag reducers and fracturing fluid.Compared with oil-phase solvents,environment-friendly green chemical products reduce secondary treatment problems.This kind of dispersion polymerization has the characteristics of simple reaction process,low cost,less pollution,easy reaction control and better polymer performance.At present,although there are many reports on the preparation of cationic polyacrylamide by dispersion polymerization,no product has been formed for many years.This article choose the diethylene glycol butyl ether?DBG?as dispersant,in the ammonium sulphate?NH₄?₂SO₄ aqueous solution as a dispersion medium system,,acrylamide?AM?and methyl acryloyl oxygen ethyl trimethyl ammonium chloride?DMC?as monomer of reaction,the introduction of ammonium persulfate and sodium bisulfite as initiator conditions,and it is obtained by using the preparation methodofthedispersionpolymerizationcationic polyacrylamide?PAM-DMC?copolymer.Throughsinglefactor experiment,the influences of dispersant type and dosage,monomer type and dosage,polymerization time,polymerizati on temperature,pH value,initiator dosage,ammonium sulfate content in dispersing medium,and monomer mass fraction on product characteristics were investigated.Research shows that the dispersant dosage of diethylene glycol butyl ether is 10%,when the reaction temperature up to 40?,the initiator system?sodium bisulfite-ammonium persulfate?is 0.02%,pH=6⁷,DMC is 6%,the reaction time is 6h,m?AM?:m?DMC?=5:1,20%ammonium sulfate content,under the condition of 20%of total monomers,dispersion and stability are better dispersion can be obtained.Polymer viscosity and conversion are best at this time.In this experiment,the structure of copolymer PAM-DMC is characterized by FTIR,SEM,XRD and ¹H-NMR.Copolymer PAM-DMC is amorphous molecule.Particle size analysis and transmission electron microscopy test on the dispersion solution of copolymer PAM-DMC showed that spherical or ellipsoidal particles with a particle size of about 100⁵00nm were uniformly distributed in the dispersion medium,with an average particle size of 198.6nm.The copolymer PAM-DMC has good thermal performance.Turbiscan Lab stability analyzer is used to test the stability of PAM-DMC dispersion solution to obtain kinetic instability index?TSI??0.13.When the copolymer PAM-DMC polymer concentration is 5%,under the condition of 90?,the shear rate control of 170s^-1,the apparent viscosity of the system can reach 30mPa s.The se show that the polymer has good heat resistance.The relationship between viscoelastic modulus,strain,frequency and time of copolymer PAM-DMC was studied.With the increase of temperature,the association of DMC was destroyed,and ammonium sulfate in the solution intensified the thermal movement,showing good temperature resistance.Under the condition of 25?,dispersion dissolved in water faster,to join the interaction between sodium chloride and ammonium sulfate,the electrostatic shielding effect is weaker than the commonly used polymer,therefore,has the good salt resistance.The results show that the cle ar water viscosity of 3%copolymer pam-dmc dispersion is 120mPa·s,the viscosity of 10000ppm NaCl solution is 57mPa·s,and the retention rate of brine was 47.5%.The flocculation performance of the synthesized copolymer is tested by uspectrophotometer?UV?,and it is found that when the molecular weight is 0.85×10⁶,the flocculation rate of the polymer reaches the maximum,the dissolution time of the polymer is 156min,the cationic degree is 7.59%,and the characteristic viscosity is98mPa·s.