环糊精改性聚羧酸系减水剂的制备与性能

Preparation and Properties of Modified Polycarboxylate Superplasticizer by Cyclodextrin

摘要:

以丙烯酸（AA）、甲基丙烯磺酸钠（MAS）、马来酸酐接枝β-环糊精（MAH-β-CD）和甲基烯丙基聚氧乙烯醚（APEG）为原料，通过水溶液自由基共聚制备了β-CD改性聚羧酸减水剂 (MPC)。考察了反应物摩尔比、引发剂用量、反应时间及反应温度对减水剂性能的影响。当单体摩尔比n(AA) : n(MAS) : n(MAH-β-CD) : n(APEG) 为5 : 0.5 : 0.1 : 1、引发剂过硫酸铵(APS)用量为单体总量的5 %、反应温度为90 °C、反应时间为5 h时，所得减水剂性能较好。应用结果表明其掺后水泥净浆流动度可达306 mm、初凝时间为440 min、减水率达32.2 %。SEM和强度测试结果表明掺有MPC的水泥石的结构更加紧密匀质，孔洞更加微小，有利于混凝土后期结构的发展。

Abstract:

Modified polycarboxylate superplasticizer (MPC) was synthesized by free radical copolymerization of acrylic acid (AA), methyl acrylic acid sodium (MAS), β-cyclodextrin grafted maleic anhydride (MAH-β-CD) and methylacrylic acid polyethylene oxide ether (APEG) using ammonium persulfate [(NH4)2SO4, APS] as initiator. Effects of mole ratio of reactants, dosage of initiator, reaction temperature and reaction time on the properties of superplasticizers were investigated. The optimum MPC was synthesized when the molar ratio of n(AA) : n(MAS) : n(MAH-β-CD) : n(APEG) were 5 : 0.5 : 0.1 : 1 using 5 wt% APS at 90 °C for 5 h. The application results show that the fluidity of cement paste can reach 306 mm, the initial setting time is 440 min and the water reducing ratio is 32.2 %. SEM and compressive strength results show that the microstructure of hardened cement doped with MPC are more homogeneity and the porosities are smaller, which are benefit for the development of later structure of concrete.