Study On Soap-free Polymerization Technology Of Acrylic Ester Compound Emulsion

Pickering emulsion used to be stabilized by solid particles instead of traditional surfactant.Pickering emulsion made up for the shortcomings of toxicity,poor stability,the hard separation of emulsifying agent,and the environmental pollution of traditional emulsion.In this paper,Pickering emulsion was as the main line,and the three different kinds of solid particles?oxidized starch,carboxymethyl cellulose sodium and nanocrystalline cellulose?was used to stabilize Pickering emulsion.Properties of emulsion were studied.1.First of all,oxidized starch,styrene and butyl acrylate were used as main raw material,the method of soap-free emulsion polymerization was adopted to synthesize oxidized starch grafted styrene acrylic copolymer latex.The optimum reaction conditions are obtained: when the ratio of styrene and butyl acrylate as 1:1,w?NaHCO₃?= 0.5%,w??NH₄?₂S₂O₈?= 1%,w?oxidized starch?= 4%,the conversion rate of styrene acrylic polymer emulsion reached 96%,particle size was 204.8 nm,the value of Cobb was 24.6 g/m2.At this moment,emulsion had good stability and water resistance.2.Then,CMC-Na,methyl methacrylate,butyl acrylate and acrylic acid were used to be as the main raw materials,the method of soap-free emulsion polymerization was adopted to synthesize carboxymethyl cellulose sodium grafted acrylate copolymer emulsion.And the optimum condition for synthesis of polymer emulsion was obtained: when the monomer ratio of 1:1,w?NaHCO₃?= 0.5%,w??NH₄?₂S₂O₈?= 1%,w?CMC-Na?= 3%,solid content reached 24.12%,conversion rate was 96.49%,the average particle size was 152 nm,and the contact Angle of sodium carboxymethyl cellulose was 36.59 ° < 90 °.The sizing degree of emulsion reached a maximum of 37 s,the emulsion had good stability and water resistance.3.The preparation of styrene Pickering emulsion was made by using NCC as solid particle stabilizers.The results showed that NCC prepared by sulfuric acid hydrolysis was rodlike,the determination of particle size was 187.2nm,crystallinity was 67.19%,and the contact angle was 59°,which make solid particles stabilizer emulsify styrene monomer.The results showed that the stable styrene Pickering emulsion can be obtained within 20 d,and emulsion rate eventually stabilized at about 0.7.Then styrene emulsion was polymerized under the condition of ammonium persulfate,and the conversion rate of polystyrene latex was around 80%,and when the content of NCC was in 4%,sizing degree of approximately 21.5g/m2 is best.But with the extension of time,the NCC stablizing Pickering emulsion could produce different degree of instability,no long-term stability.4.In the fifth chapter,the process of NCC stablizing styrene monomer was changed.So it was studied that the preparation of polymers was finished in advance and then the phase of styrene emulsion was reversed,polymerization was conducted in the final part.The results showed that when the content of NCC was 3g/L,the maximum conversion rate of polystyrene Pickering emulsion was 90%;with the increase of the content of NCC,emulsion particle size decreased.The resulting styrene Pickering emulsion stabilized by NCC can exist for a long time.