梳形结构的侧链密度对聚羧酸系减水剂性能的影响  

Effect of Side Chain Density of Comb-shaped Structure on Performance of Polycarboxylate Superplasticizer

作　　者：王子明[1] 卢子臣[1] 路芳[1] 李慧群[1] 

机构地区：[1]北京工业大学材料学院,北京100124

出　　处：《硅酸盐学报》2012年第11期1570-1575,共6页Journal of The Chinese Ceramic Society

基　　金：国际科技合作项目(S2011GR0398)资助

摘　　要：根据自由基聚合反应原理,通过聚合物分子结构设计和优选合成工艺方法,合成一系列主链聚合度不变、侧链密度不同的梳状结构聚羧酸系减水剂(PCA)。采用凝胶色谱仪测定PCA分子量分布及未反应单体含量。结果发现,对于聚合度为50的聚醚大单体,反应单体的酸醚比在2.5:1以下时,聚合反应转化率较低。为准确反映PCA结构对性能的影响,采用常规添加法、有效聚合物等质量添加法及等摩尔添加法测定不同结构PCA对水泥初始流动度及保持能力的影响,结果表明:随着侧链密度的减小,水泥初始净浆流动度增加;当侧链密度低于25%后,继续减小侧链密度,初始流动度增加不明显;水泥净浆流动性保持能力随侧链密度的减小而显著下降。A serial of polycarboxylate superplasticizers （PCA） with the same main chain length and gradually decreased side chain density were synthesized via the design of the polymer structure and the optimization of the synthesis technology based on the reac- tion theory of free radical polymerization. In addition, their molecular mass, molecular mass distribution and the conversion ratio were measured by gel permeation chromatograph. The results reveal that the polymerization rate is low when the acid to ether ratio is less than 2.5：1 for the macromonomer with a polymerization degree of 50. In order to investigate the effect of the PCA structures on the performance, the cement paste fluidity experiments were conducted with three different adding methods, i.e., conventional mass adding method, same amount of effective PCA adding method and equimolar PcA adding method, respectively. The results show that the initial fluidity of cement paste increases and the fluid-retaining ability decreases with decreasing the side chain density. When the side chain density was less than 25%, the initial fluidity of cement paste would not improve obviously. However, the fluid-retaining ability decreased dramatically with the decrease of side chain density.

关 键 词：聚羧酸减水剂 侧链密度 凝胶色谱 水泥流动性 

分 类 号：TU528[建筑科学—建筑技术科学]