The Preparation Of Solid Polycarboxylate Superplasticizer By Bulk Polymerization And Study On Its Properties

Polycarboxylate Superplasticizer(PCEs)is widely used in construction engineering because of its low dosage of mixing,high water reduction,good workability,simple synthesis technology and the advantages of environmental protection.At present,most of the polycarboxylic water reducers on the market are liquid,and its solid content ranges from 10% to50%;For long-distance construction,transportation is difficult and the cost is high.At the same time,it also causes the limitation of its application field.In the production process of construction products,such as dry mortar and slurry,polycarboxylate superplasticizer must be solid.Although there are also a few solid polycarboxylic water reducers produced by the spray drying process on the market,the curing process is complicated,the energy consumption is large,the cost is high,and there are potential safety hazard.Therefore,the study on direct preparation of solid polycarboxylic water reducers is of great significance topic.In this paper,firstly,APEG-MS-type SPCEs with good performance were synthesized directly by bulk polymerization without water and any other solvents.propylene glycol polyoxyethylene ether(APEG-1200)was used as macromonomer,maleic acid(maleic acid,abbreviated as MS)was used as small molecule,and azobisisobutyronitrile(AIBN)was used as initiator.Then,HPEG-MS-type SPCEs was prepared,with isobutylene alcohol polyoxyethylene ether(HPEG-3000)and maleic acid under the initiation of AIBN,by bulk polymerization method without any other solvent.At the same time,the effects of acid-ether ratio,reaction temperature,reaction time,initiator dosage and the mode of adding of initiator on the dispersion property of the polymer products and conversion rate of polymerization monomer were studied by a single factor experiment.The synthesized solid PCEs was characterized by gel chromatography(GPC),infrared spectroscopy(FTIR)and thermogravimetry(TG),the results showed that the bulk polymerizationproceeded smoothly and the target product was obtained;A series of performance tests were performed on the synthesized solid PCEs,such as cement paste fluidity,concrete slump,setting time,gas content,compressive strength,etc.And compared with commercially available liquid polycarboxylic acid water reducers.The results show that the bulk polymer of solid PCEs product has strong dispersibility and good dispersion retention,and it has excellent performance in concrete applications,and meets the performance requirements of commercially available liquid polycarboxylic acid water reducers.