The synthesis technique of polyacrylic acid superplasticizer

Using water separation technique, acrylic acid (AA) and polyethylene glycol (PEG) 1000, of which the ratio was 1.5, were esterified and the optimum esterification ratio of 90% could be reached under the condition of 110 °C × 3 h. Using polyoxyethylene acrylate macromonomer (PA) prepared in the esterification, AA and sodium methylacryl sulfonate (MAS) as monomers, a copolymer which could be used as superplasticizer was prepared by free radical copolymerization in n(PA):n(AA):n(MAS) of 1:7:3. When the synthesis condition was 80 °C × 5 h, the optimal dosage of initiator was 3.0%–4.0%, the fluidity of cement paste with the sample could reach 270 mm. By analyzing the effect of the content of residual small molecule sulfonic monomer on the properties of sample, n(MAS)/n(PA) was controlled in a range of 2.5–3.8.