| With flexible structure, controllable molecular weight and high steric effect,macromolecular dispersant as a new generation of dispersant is widely used as aceramic dispersant, dye dispersant, scale inhibitor, builder and water treatment agentbecause its molecular weight and molecular structure can be changed according to theactual need. However, due to the higher price, limited monomer source, poor stabilityand other shortcomings that limit its application, the development of new andefficient green macromolecular dispersant become an important task. In this paper,we used itaconic acid monomer belonging to biomass resources and containing twocarboxyl functional groups and acrylic monomer to copolymerize, used radicalpolymerization and reversible addition-fragmentation chain transfer (RAFT)polymerization methods for the synthesis of biodegradable Poly(acrylicacid-co-itaconic acid)(Poly(AA-co-IA)), which improved chelating force anddispersion force of macromolecular dispersants, and investigated the pretreatment ofmonomer, initiator concentration, reaction temperature, reaction time and monomerratio in the process of the polymerization. The content of residual double bondswere measured with brominated method to calculate double bond conversion topolymer. The efflux time of polymer solution was detected by an ubbelohdeviscometer, which was used to deduce intrinsic viscosity of the polymer. Thechelating force and dispersion force were characterized by titration. The polymermolecular weight and its distribution were characterized by gel permeationchromatography (GPC). The structures of the polymer was characterized by fouriertransform infrared spectroscopy (FTIR). As a result, the best reaction condition wasfound. The details were as follows.(1) When the ordinary radical polymerization was used to synthesize thepolymer, the monomer’s conversion was improved by neutralizing acrylic acid anditaconic acid with NaOH of the equimolar amount under ice-cooling, which made forobtaining polymer with good performance in the method of treating monomers. (2) Under the general solution radical polymerization, a serious of polymerswere synthesized with different reaction time, reaction temperature, initiator contentand monomer ratio. Compared with these polymers, the optimum reaction conditionwas as follows. The reaction time was3h, the reaction temperature ws80℃, theinitiator content (mass ratio) was6%of the total monomer and the molar ratio of theacrylic acid and itaconic acid was7:3. Under this condition, polymers had the mostoutstanding comprehensive performance. The dispersion force and chelating force ofpolymers could be up to59.3mg.g-1and312mg.g-1, respectively.(3) The S,S’-(α, α’-methyl-α "-acetic acid) trithiocarbonate as a RAFT chaintransfer agent was synthesized by phase transfer method to obtain PAA andPoly(AA-co-IA). The dispersion force and chelating force of polymers werecharacterized, showing that the performance of polymers was superior to that ofpolymers by general radical polymerization. When the best molar ratio of acrylic acidand itaconic acid was1:4, the dispersion force and chelating force of polymersreached to76.3mg.g-1and412mg.g-1, respectively.(4) The Poly(AA-co-IA) synthesized in two ways was used as dispersant todisperse CaCO3and kaolin slurry. In the process of dispersing CaCO3, the minimumkinematic viscosity of calcium carbonate slurry was8.6mm2/s when the mass ratio ofPoly(AA-co-IA) synthesized by conventional free radical polymerization and calciumcarbonate slurry was0.3%. While its minimum kinematic viscosity was8.7mm2/s, themass ratio of them by RAFT was0.2%. In the process of dispersing kaolin, theminimum kinematic viscosity of kaolin slurry was21.1mm2/s when the mass ratio ofPoly(AA-co-IA) synthesized by conventional free radical polymerization and kaolinslurry was0.25%with saturation value. While its minimum kinematic viscosity was16.2mm2/s, the mass ratio of them by RAFT was0.15%. The Poly(AA-co-IA)synthesized in two ways was better dispersant than STPP to disperse CaCO3andKaolin. |
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