中和与否对聚羧酸减水剂性能的影响及机理分析

Effect of Whether or Not to Adopt Neutralization on the Performance ofPolycarboxylate Superplasticizer and Mechanism Analysis

聚羧酸减水剂在合成过程中是否中和对产品性能的影响显著。采用净浆流动度、总有机碳分析仪、X射线光电子能谱、红外光谱、动态光散射和Zeta电位仪,研究了聚羧酸减水剂是否中和对其分散性、吸附量、吸附层厚度及初始构象和吸附构象的影响。结果表明,与已经中和的减水剂相比,掺加未中和的聚羧酸减水剂的水泥浆体初始流动度更大、流动度经时损失更小;相同掺量时,未中和聚羧酸减水剂吸附量较低但吸附层厚度更厚,这是由于未中和的聚羧酸减水剂分子在溶液中的初始构象侧链更为伸展,因此吸附后的吸附构象也占据更大的空间,使吸附层变厚,对水泥颗粒的分散性更好。

The neutralization process of polycarboxylate superplasticizers in the synthesis process has a significant effect on the property of product.The effects of neutralization process on the dispersion,adsorption capacity,thickness of adsorption layer,initial conformation and adsorption conformation of polycarboxylate superplasticizer were studied by cement paste fluidity,total organic carbon analyzer,X-ray photoelectron spectroscopy,infrared spectroscopy,dynamic light scattering and Zeta potential.The results showed that compared with the neutralization process,when polycarboxylate superplasticizers produced by unneutralized process was mixed with cement,the initial fluidity of cement paste was higher,the loss of fluidity was smaller and the adaptability to cement was better.At the same dosage,the adsorption amount of unneutralized polycarboxylate superplasticizer is lower,but the thickness of the adsorption layer is thicker.Due to the fact that the initial conformation branched chain of the unneutralized polycarboxylate superplasticizer molecule in the solution is more extended,the adsorption conformation after adsorption also occupies a larger space,so that the adsorption layer is thicker,and the dispersibility of the cement particles is better.