聚丙烯酸钠陶瓷减水剂的制备及分散性能研究

Preparation and Performance of Sodium Polyacrylate for Ceramic Superplasticizer

摘要:

以丙烯酸为单体，过硫酸铵-亚硫酸氢钠为氧化还原引发体系，亚硫酸氢钠为链转移剂，制得可用于分散陶瓷浆料的中等分子量聚丙烯酸钠。探讨了过硫酸铵用量、亚硫酸氢钠加入量、单体含量及反应温度对聚合物分子量的影响，并对不同分子量的产物在陶瓷料浆中的流动性进行了考察。聚丙烯酸钠的最佳合成条件为：过硫酸铵用量为单体总质量的0.8%，亚硫酸氢钠用量为单体总质量的10%～12%，单体占溶液总质量的24%～26%，反应温度为70℃～80℃。采用FT-IR、GPC对聚合物进行表征，并对添加不同量聚合物的料浆Zeta电位、粘度及其复合后制得粗坯的弯曲强度进行了研究。结果表明：聚合物浓度为1 g/L时，Zeta电位绝对值由27.4 mV升高到78.4 mV。聚合物添加量为0.25%，料浆体系的粘度从996 mPa•s降低到179 mPa•s。与添加无机陶瓷分散剂及聚合物的陶瓷粗坯样条相比，聚合物与无机电解质三聚磷酸钠以质量比1:1复合后制得的粗坯弯曲强度可提高33.33%。

Abstract:

Medium-molecular weight sodium polyacrylate for ceramic superplasticizer was synthesized from acrylic acid as monomer, while ammonium persulfate/sodium bisulfite as redox initiator, sodium bisulfite as reducing agent. We investigated the factors having effects on the polymer’s average molecular weight such as redox system, monomer, and temperature. Moreover, the fluidity and dispersing properties in the ceramic slurry were investigated after adding polymers. The optimum reaction conditions for synthesizing ceramic superplasticizers are as follows: the adding amount of ammonium persulfate is 0.8 %, the amount of sodium bisulfite is 10 %～12 %, the mass fraction of acrylic acid is 24 %～26 %, reaction temperature is 70℃～80℃. The synthesized superplasticizer was characterized and analyzed by FT-IR and GPC, and the effects of different reaction conditions on the viscosity and dispersion of ceramic’s slurry were investigated. The results show that the slurry’s negative Zeta potential increases from 27.4 mV to 78.4 mV when the concentration of polymer is 1000 mg/L. And the minimum value of slurry’s viscosity is 179 mPa•s when the concentration of sodium polyacrylate is 0.25% (based on the absolute dry slurry). The ceramic body with composite components of polymer and sodium tripolyphosphate (w/w=1:1) has higher bending strength, which is increased by 33.33%.