聚羧酸盐高效减水剂的制备及性能影响因素

Research on Preparation Techniques and Factors Affecting Properties of Polycarboxylate Based Superplasticizer

以甲氧基聚乙二醇(1000)甲基丙烯酸酯(MPEGMA)为主要原料,研究了添加甲基丙烯酸(MAA)、烯丙基磺酸钠(ALS)及过硫酸铵(APS)聚合生成羧酸盐减水剂的制备技术及性能影响因素,分析了MAA与MPEGMA的物质的量之比,ALS与APS掺量以及原材料加入方式、保温时间对聚羧酸盐减水剂分散性及其保持能力的影响,得到了聚合反应的最佳工艺条件是:MAA∶MPEGMA为3∶1,ALS和APS用量分别为MAA和MPEGMA总质量的3%和7%,反应温度80℃,单体混合液滴加时间为2～2.5 h.应用上述工艺参数对合成的不同酯化率的3种分子质量的甲氧基聚乙二醇(4006,00和2000)甲基丙烯酸酯分别制备了减水剂,结果发现当侧链分子质量较小时(如400,600)水泥净浆初始流动度略小但流动度保持性好,侧链分子质量较大时(如2000)初始分散性较好但分散保持性较差,侧链分子量一定时水泥初始净浆流动度随酯化率提高有增大的趋势.

The preparation techniques and factors affecting properties of polycarboxylate based superplasticizer is investigated by polymerization reaction using MPEGMA（methoxy polyethylene glycol（1000） methacry-late）,the MAA（methyl acrylic acid）,sodium allyl sulfonate（ALS） and ammonium persulfate（APS）.The effects of mole ratio of MAA to MPEGMA,dosage of ALS and ammonium persulfate,feeding mode and holding time of reaction temperature on the plasticizing properties and fluidity retaining ability of polycarboxylate super-plasticizer are analysed.The optimal condition for polymerization reaction includes： the ratio of nMAA to nMPEGMA is 3.0,the amount of ALS is 3% of the mass of MAA and MPEGMA,the amount of ammonium persulfate is 7% of the mass of MAA and MPEGMA,the reaction temperature is 80 ℃,the dropping time for mixture of monomers is 2 ～ 2.5 h.Application of the optimal condition for polymerization reactiont,he superplasticizers are prepared using MPEG（400,6002,000） MA of different esterification rate.The test results show that the in-itial fluidity of cement adding superplasticizer with lower molecular weight of side chain（such as 400,600） is slightly smaller,but fluidity retention is good.On the contrary,along with increase of the side chain molecular weight of superplasticizer（such as 2000）,the initial dispersion of cement is better but fluidity retention is poor.The results also show that the initial fluidity of cement adding superplasticizer is basically proportional to the esterification rate of the macromer MPEGMA.