Synthesis And High Performance Of Polycarboxylated Superplasticizers

Polycarboxylated superplasticizer (PCs), one of the concrete additives, has been moreimportance in the21’st century because of its advantages such as small admixture, high waterreducing ratio, well restraint of slump loss and programmable molecular structure. It detailintroduced the research and development of polycarboxylated superplasticizer, the syntheticmethods and mechanisms were analyzed in this thesis. According to principles of molecularstructure design，polycarboxylated superplasticizer was synthesized by two steps, and studyedthe relationship between structure and properties of polycarboxylated superplasticizer.The methoxypoly (ethylene oxide) acrylate (MPEGA) macromonomer has beensynthesized with acrylate acid and methoxy poly (ethylene oxide) monoether (MPEG) by theorthogonal experimental design. The copolymers were characterized with FTIR and GPC andits highest esterification rate is95%.Polycarboxylated superplasticizer with carboxyl, sulfonic, amide and the PEO side chainwas synthesized by free radical aqueous solution polymerization, the copolymers werecharacterized with FTIR and EDS. The effect of the as-prepared polycarboxylatesuperplasticizers on cement were investigated. The hydration process of cement joinedself-made polycarboxylate superplasticizers were characterized with XRD, SEM and EDS.The performance showed that the carboxyl, sulfonic, amide group, especially carboxyl,greatly influences the dispersion of paste, and both polyoxyethylene side chain and amidegroup has a significant effect on the security of plasticity, which the former is greater than thelatter. Dispersion and plasticity of water reducer by dropping ammonium persulfate aqueousand AA, MPEGA aqueous respectively to sodium allysulfonate acrylamide aqueous are thebest, while molar ratio of n(AA):n(MPEGA):n(AM): n(SAS)=3.75:1.00:3.75:2.5.The effect of polycarboxylated superplasticizer on cement and concrete are studied,which result indicated that self-restraint has better compatibility with OPC concrete. Highwater reducing rate (about30%) and well restraint of slump, while mixed with copolymerwhich is0.5%by weight of concrete (cement).