Study On The Preparation And Flocculating Performance Of High Molecular Weight Polyaciylamide

Acrylamide-based polymer, which is called polyacrylamide （PAM） normally andwell known for their good solubility in water and environment friendly, and has beenused in many fields such as water treatment, oil production, paper making, mining andmetallurgy, pharmacy and fluid transport for the function of thickening, flocculatingand regulating rheological behaviour.There are some problems in the study of PAM’ preparation and application:1.Viscometry is used to determining the molecular weight of PAM, but the dissolubilityof PAM with the higher molecular weight is not good. To solve the problem, alkaliwas added when determining the molecular weight of PAM for accelerating thehydrolysis, but it affected the actual viscosity-average molecular weight and themolecular weight determined was deviate from the actual molecular weight.2.Although China is the biggest country of consuming PAM in the world, cationic PAMdepends on import, so the study of cationic PAM is necessary important.3. Themolecular weight distribution of PAM prepared by traditional method is too wide, andsome monomer is residual, which makes the pollution of water, so it is not equippedwith preponderance in industrial applications.The study presented a simple method for rapidly and accurately determining theactual viscosity-average molecular weight of partial hydrolytic PAM on the basis of aseries of experiments. After that cationic PAM was synthesized by inverse emulsionpolymerization with acrylamide （AM） and dimethyl diallyl ammonium chloride（DMDAAC） as the monomers, and molecular weight, flocculation effect and thestructure were characterized. Finally nonionic PAM was prepared by reverse atomtransfer radical polymerization with AM as the monomer, and molecular weight,flocculation effect and the structure were studied, the results were shown as follows:1. Influence of pH on the viscosity-average molecular weight of PAM wasstudied systematically. And a simple method for rapidly and accurately determiningthe actual viscosity-average molecular weight of partial hydrolytic PAM waspresented. With the use of the equation[M_η]_D=d+e[M_η]_A（where [M_η]_D was theapparent viscosity-average molecular weight of PAM after partially hydrolyzing in agiven concentration of NaOH,[M_η]_A denoted the actual viscosity-average molecularweight of PAM before hydrolyzing, d and e were both constants related to theconcentration of NaOH）,[M_η]_A could be obtained expediently. The method presentedin this work was proved to be valid and possessed good accuracy, precision and universality through examining.2. The cationic polyacrylamide with high molecular weight was prepared byinverse emulsion polymerization with acrylamide （AM） and dimethyl diallylammonium chloride （DMDAAC） as the monomers, cyclohexane as continuous phase,span80and tween80as compound emulsifiers and hydrogen peroxide （H₂O₂）-ascorbicacid （Vc） as the initiator. The influence on PAM’s molecular weight andsedimentation percent of stirring rate, monomer concentration, ratio of AM toDMDAAC, volume ratio of cyclohexane to water, emulsifier concentration, ratio ofspan80to tween80, initiator concentration, reaction time and reaction temperaturewere studied. And the structure of PAM was also characterized.3. PAM was prepared by reverse atom transfer radical polymerization with AM asthe monomer, iron （Ⅲ） as catalytic system, potassium persulfate （KPS） as the initiator,orthophenanthroline （phen） as ligand. The influence on PAM’s molecular weight andsedimentation percent of ratio of FeCl₃to phen, initiator concentration, monomerconcentration, emulsifier concentration, ratio of span80to tween80, reaction time andreaction temperature were studied. And the structure of PAM was also characterized.