Interaction In Polyacrylamide Blend Aqueous Solution And Its Copolymer Application In Viscosity Enhancement

Reversible addition-fragmentation chain transfer polymerization method(RAFT)is used in aqueous radical polymerization with prepared S,S'-bis(?,?'-dimethyl-?"-acetic acid)-trithiocarbonate as a water-soluble RAFT reagent,azobisisopropyl imidazoline hydrochloride(VA044)or KPS as the initiator,and acrylamide(AM),methacryloxyethyl dimethylbenzyl ammonium chloride(AODBAC),methacryloyloxyethyl trimethylammonium chloride(DMC)and other acrylamide monomers to synthesize narrow distribution homopolymers.The thesis discusses the influences to performance of the polymerization produce from initial monomer concentration,the raw material ratio of the monomer and initiator to the RAFT reagent,and polymerization temperature.Precise control of relative molecular mass of water-soluble polymer is realized.Using bromination titration based on double bond addition,GPC and 1H NMR detection methods proved that in the controllable/active free radicals in the acrylamide-based monomer aqueous solution,the reaction conversion rate of the polymerized product is high,relative molecular mass is similar to the design value,molecular weight distribution index is small with good uniformity.It provides an ideal material of narrow-distribution polymer for exploring the viscosity and interaction of water-soluble polymer blend solution.The blending experiment was carried out using the narrow distribution of PAM,PDMC and PAODBAC with designed molecular weight and narrow distribution.Particle size distribution of the narrow-distributed homopolymer aqueous solution and its blended solution was observed with a nano particle size analyzer.The UV-Vis spectrophotometer furtherly verified the corresponding micro-interactions in blend solution.It is speculated that there exists corresponding microscopic interaction:the quaternary ammonium groups of PDMC and PAODBAC form a strong electrostatic interaction in the solution,and PAM produce s an effective electrostatic shielding effect on the blend solution.The rheometer was used to characterize the change of the viscosity of the PAM-PDMC and PAM-PAODBAC blended aqueous solutions with the mole percentage of PDMC,and it was found that there is a maximum point in the viscosity change process.In order to explain and predict the viscosity phenomenon of the solution,the paper first proposed a semi-theoretical and semi-empirical model for correlating the viscosity of aqueous solutions of polyacrylamide polymers.Through using experimental value of the viscosity of polyacrylamide blend solution,the effective estimation value of 6 unknown group interaction parameters was obtained by using genetic algorithm,which are used to complete the parameter table and apply it to the viscosity prediction of different blend solutions.The Eyring thermodynamics-viscosity correlation theory model is adopted.The Flory-Huggins theory that expresses mixed entropy,the group contribution model that expresses microscopic interactions between groups,and the PDH model that expresses electrostatic interactions are used to solve the excess Gibbs free energy required by the Eyring model.Based on the characteristics of the polyelectrolyte solution,the PDH model was modified reasonably to predict the influence of the electrostatic shielding effect in the polyelectrolyte solution on the viscosity of the solution.Finally,the effective scope of application of this model is discussed in terms of total concentration,relative molecular weight of each polymer,temperature and polymer solute structure.Satisfactory prediction results have been obtained in solutions with different conditions.In the acrylamide copolymer,AM is the basic structural monomer with small volume and high polymerization activity,which can effectively improve the relative molecular weight of the copolymer.By copolymerizing AM with two functional monomers G1 and G2,a new type of PAM thickener used in the petroleum extraction industry was prepared,and the preparation conditions were optimized to increase the apparent viscosity of the polymerized product under simulated oil recovery conditions.The optimal preparation conditions are determined as follows:AM:G1:G2 mass ratio is 6:3:1,the ratio of crosslinking agent BIS to total monomer mass is 0.03 wt%,total monomer concentration is 25 wt%,initiator KPS The concentration is 0.3 wt%,and the reaction temperature is 30?.