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Preparation of Anionic Polyacrylamide by Aqueous Two-phase Polymerization

Author: CaiXiaoSheng
Tutor: DanGuoRong
School: Zhejiang University
Course: Chemical Engineering
Keywords: Aqueous two-phase polymerization Anionic polyacrylamide Hydrophobic monomers Critical phase separation Into droplets mechanism
CLC: O633.22
Type: Master's thesis
Year: 2011
Downloads: 43
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Abstract

Using azo initiators for aqueous two-phase polymerization of initiator acrylamide (AM) was prepared to obtain a stable anionic polyacrylamide (APAM) an aqueous dispersion. The effects of different parameters such as comonomer, salting media, stabilizer aqueous two-phase the system polymerization process and performance, and to determine the aqueous two-phase system of various reaction parameters. Research and acrylamide (AM) / acrylic acid (AA) / monomer C in an aqueous solution containing a certain amount of sodium polyacrylate (PAANa) of ammonium sulfate (AS) dual water phase of the polymerization reaction. Visits monomer concentration, monomer ratio, relative to the conversion rate of the salt concentration, temperature and the amount of stabilizer critical points of aqueous two-phase system, the critical sub-phase molecular weight and the influence of droplet size. Investigation of the dual water phase copolymerization of the structural composition of the polymer chain and the droplet size distribution obtained into droplets of the aqueous two-phase of the polymerization process mechanism. Qe values ??of each monomer reactivity ratios, add the hydrophobic monomers C help system dispersed and gentle reaction to the AM / AA system. Through experiments to choose the hydration ability of the AS as the salting medium, with AS increase of the amount, the reaction rate becomes faster. The choice experiments: PAANa as stabilizer, the amount of the reaction rate of the aqueous two-phase system with less influence. Phase polymerization system is divided with a spectrophotometer is determined using the method for the determination of bromide conversion rate of the polymerization system when the critical demixing by gel permeation chromatography (GPC), the molecular weight of the polymer chain in the polymerization system critical demixing study, the droplet morphology was observed with an optical microscope after the critical demixing. With the increase in the amount of C, the critical sub-phase conversion and critical demixing molecular weight gradually reduced after the phase separation the liquid drops diameter smaller; AM and AA increase in the total monomers, the critical demixing conversion rate was gradually reduced, the critical demixing molecular weight becomes gradually large After phase separation, the liquid drops of diameter larger; AA increase in the mass ratio of the critical sub-phase conversion rate and critical demixing reduced molecular weight decrease after demixing diameter becomes small liquid drops; salt concentration increases, the critical The conversion rate of the phase separation is almost unchanged the critical demixing molecular weight gradually decreases, the liquid drops after demixing diameter becomes large; elevated temperatures, the system critical demixing conversion rate gradually increased the critical demixing molecular weight almost constant, after the phase separation diameter becomes large liquid drops; the amount of stabilizers increases, the critical demixing conversion rate is almost constant the critical demixing molecular weight increase amplitude becomes large, the phase separation after the liquid drops diameter larger. Gas chromatography was used to detect the residual amount of each monomer in the copolymerization process, the projection of the structure of the polymer chain: Reaction pre AM and C chain section mainly reaction medium AM chain, later reaction with AA and AM chain section of the main. Using dynamic light scattering (DLS) online testing aqueous two-phase polymerization initial droplet formation and growth regulation, and found that the droplets in the initial stage of the reaction to the presence of poly phenomenon, the droplet size distribution first widened after narrowing. The AM / AA / C into droplets containing PAANa AS aqueous solution of the aqueous two-phase of the polymerization process in mechanism, wherein the AA chain brought some negative charge is the stable dispersion of the polymerization product, liable to gather important factors.

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