The Application Of Novel Redox Initiation System In Polymerization Of Aqueous Acrylic Acid

Since the 1950s,it has been found that when using free-radical reactions to prepare polymers,the use of redox-initiated systems has distinct advantages over single oxidant-initiated systems.Such as fast reaction,adjustable range of reaction temperature,easy control of molecular weight distribution,wide application range,etc.In the free radical aqueous solution polymerization,redox-initiated systems such as persulfate-sodium bisulfite,persulfate-sodium hypophosphite,persulfate-VC-mercaptoacetic acid,and hydrogen peroxide-ferrous sulfate are gradually formed.At the same time,in order to better control the molecular weight distribution,a chain transfer catalyst such as isopropanol,dodecanethiol,thioglycolic acid and the like have also been introduced.In this dissertation,based on the study of the reaction of N-isopropylhydroxylamine(IPHA)with free oxygen in water,the analysis of oxygen removal kinetics,and the establishment of the kinetics equation for oxygen removal,it was confirmed that IPHA has good reducibility.Then it was proposed to introduce IPHA in the free radical polymerization to establish a new redox initiation system,persulfate-IPHA system.The system was initially applied to homopolymerization of acrylic acid aqueous solution,acrylic acid-methyl acrylate and acrylic acid-methyl allyl polyoxyethylene ether aqueous solution copolymerization to prepare polyacrylate type diesel pour point depressant and polycarboxylic acid type cement water reducer.Meanwhile the structures and basic properties of these two types of polymers are characterized and tested.Our main work has the following three aspects:The first,the kinetics of the reaction of IPHA with free oxygen in water was studied and it was confirmed that IPHA has a good reduction.By measuring the concentration of free oxygen in water at different temperatures,pH values,and IPHA dosages over time,the kinetics of the oxygen removal reaction of IPHA was analyzed,and the order of the reaction was determined to be a pseudo-level,and the activation energy of the reaction was calculated.Ea=71.09052 kJ/mol,the kinetic equation of the reaction was established.Second,in acrylic acid homopolymerization and acrylic acid-methyl acrylate copolymerization,poly(acrylic acid)and acrylic acid-methyl acrylate copolymers wereprepared in aqueous solution using ammonium persulfate-IPHA as the redox initiation system.The two types of polymers were respectively esterified with high carbonfatty alcohols to obtain a polyacrylic acid high carbon ester diesel viscosity reducer.Under the better synthesis conditions,when the added amount was 250 ppm,the cold filter point of the diesel base oil was obtained.It can be reduced by 4℃ to achieve the same amount of performance as the imported EVA diesel viscosity reducer.Finally,acrylic acid-methylallyl polyoxyethylene ether(TPEG)copolymers wereprepared in aqueous solution using acrylic acid-methylallyl polyoxyethylene ether(TPEG)copolymerization with ammonium persulfate-IPHA as redox initiator system.As a kind of polycarboxylic acid type cement water reducer,the copolymer can meet the requirements of similar products in the market under the better conditions.