聚醚型聚羧酸减水剂的侧链结构对其性能的影响

采用烯丙基聚氧乙烯醚(APEG)、丙烯酸(AA)、马来酸酐(MA)及甲基丙烯磺酸钠(MAS)为单体,以过硫酸铵为引发剂,在水溶液中共聚合成了具有不同长度侧链的聚醚型聚羧酸减水剂。利用凝胶渗透色谱(GPC)测定了不同侧链结构减水剂的分子质量,进而研究了不同分子质量的聚醚型聚羧酸减水剂在水泥颗粒表面的吸附行为对水泥的分散性能和水泥早期水化的影响。结果表明,水泥颗粒对聚醚型聚羧酸减水剂的吸附具有选择性,在相同条件下,水泥颗粒会优先吸附单一侧链结构聚醚型聚羧酸减水剂中分子质量较高的减水剂分子;分子质量适中的复合侧链聚醚型聚羧酸减水剂比单一侧链和分子质量过大或过小的复合侧链聚醚型聚羧酸减水剂更容易在水泥颗粒表面上发生吸附,对水泥颗粒具有显著的分散性能,同时能够显著地延缓水泥早期水化。

Effect of the side chains of ether polycarboxylic acid-type water reducers on its properties

A series of ether polycarboxylic acid-type water reducers(PCWRs) were synthesized in the water solution by using allyl polyoxyethylene ether(APEG),acrylic acid(AA),maleic anhydride(MA) and sodium methylallyl sulfonate(MAS) as monomers,and the ammonium persulfate as initiator.The different side chain length of each water-reducer was measured by gel-permeation chromatography(GPC).The adsorption behavior of the polyether water-reducers with different molecular weight on the cement particle surface,and their cement dispersibility and the effect on the early hydration of cement were investigated.The results indicated that cement particle can selectively absorb the water-reducer molecules with different molecular weight and different side chain structure.Those with high weight molecular weight among the single side chain and those with moderate weight molecular weight among the complex side chain water-reducer molecules can be preferentially absorbed on the surface of cement particle under the same experimental conditions.The water-reducer molecules with complex side chain and moderate weight molecular weight possess remarkable dispersibility for cement and can also obviously delay the early hydration of cement paste.