The Preparation And Performance Research On Poly-carboxylic Series Of Superplasticizer

Polycarboxylic water-reducer exhibits an excellent ability of water-reducing and controlling slump losses. However, polycarboxylic acid type water-reducer with different structures has different water-reducing performance and slump-keeping capability. Research on the structure of polycarboxylic acid water-reducer and the connection between the structure and the properties have gotten wide-spread attention at home and abroad.In this thesis, polycarboxylic type water-reducer was synthesized by the method of two steps, and the molecule frame of the chemical structure of high performance water-reducers was designed. Using methyl acrylic acid and three kinds of methoxy polyethylene glycol with different molecular weight series esters with macromolecule were prepared by direct esterification reaction. And then polycarboxylic water-reducers with different structure were synthesized by radical polymerization in aqueous system which are the mixture of methoxy polyethylene glycol acrylate, methacrylic acid, and sodium methallyl sulfonate. The results showed that the dispersive and dispersive retentivity of polycarboxylic water-reducer with interphase structure of long side-chain and short side-chain were better than polycarboxylic acid type water-reducer with single side-chain. It showed characteristics of the super plasticizer functional groups through the research of infrared spectrum and nuclear magnetic resonance.The reactant ratio, process parameters and control conditions of polymerization reaction were studied because they had influence on the dispersive property and dispersing retention property of polycarboxylic water-reducer. Furthermore, the optimized reactant ratio and process condition of polycarboxylic water-reducer was obtained.At the meantime, the performance of water-reducer prepared in lab was tested according to correlative standard of concrete. The results showed that the water-reducer possessed a lot of characteristics such as low dosage, high water-reducing ratio, good ability of prevention of slump loss, which improved the properties of green and hardened concrete remarkably.