两性聚羧酸减水剂对水泥基材料分散性能的影响
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摘要
通过自由基聚合制备了侧链长度一致、重均分子量相当的吸附基团比例不同的两性PCE。通过溶液构象、吸附性能和分散性能的表征,系统地研究了其对水泥基材料分散性能的影响规律。结果表明:随着吸附基团中AM比例的增加,两性PCE的流体力学半径不断降低,空间位阻效应不断减小,吸附量呈现先增加后减小的趋势,对水泥颗粒的亲和性先降低后增加,饱和吸附量As呈现先增加后减小的趋势,分散性能逐渐降低。
Amphoteric PCE with same side chains length,same weight average molecular weight and different proportions of adsorption group was prepared through free radical polymerization. The influences of amphoteric PCE with different proportions of adsorption group on the dispersion properties of cementitious materials were systematically studied through solution conformation,adsorption properties and dispersion properties. The results showed that with the increase of AM ratio in the adsorption group,the hydrodynamic radius of the amphoteric PCE decreased,the steric hindrance effect decreased,and the adsorption amount first increased and then decreased. The affinity for the cement particles decreased first and then increased,while the saturation adsorption amount increased first and then decreased,and the dispersion performance gradually decreased.
Amphoteric PCE with same side chains length,same weight average molecular weight and different proportions of adsorption group was prepared through free radical polymerization. The influences of amphoteric PCE with different proportions of adsorption group on the dispersion properties of cementitious materials were systematically studied through solution conformation,adsorption properties and dispersion properties. The results showed that with the increase of AM ratio in the adsorption group,the hydrodynamic radius of the amphoteric PCE decreased,the steric hindrance effect decreased,and the adsorption amount first increased and then decreased. The affinity for the cement particles decreased first and then increased,while the saturation adsorption amount increased first and then decreased,and the dispersion performance gradually decreased.
引文
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[2] Lia C Z,Feng N Q,Li Y D,et al. Effects of polyethlene oxide chains on the performance of polycarboxylate-type water-reducers[J].Cement and Concrete Research,2005,35:867-873.
[3] Plank J,Sakai E,Miao C W,et al. Chemical admixtures—Chemistry,applications and their impact on concrete microstructure and durability[J]. Cement and Concrete Research,2015,78:81-99.
[4] Liu X,Wang Z M,Zhu J,et al. Synthesis,characterization and performance of a polycarboxylate superplasticizer with amide structure[J]. Colloids and Surfaces A:Physicochemical and Engineering Aspects,2014,448:119-129.
[5] Miao C W,Ran Q P,Liu J P,et al. New generation amphoteric comblike copolymer superplasticizer and its properties[J]. Polymers and Polymer Composites,2011,19:1-8.
[6]冉千平,刘加平,缪昌文,等.两性羧酸类接枝共聚物混凝土超塑化剂的制备与性能评价[J].建筑材料学报,2007,10:573-576.
[7] Plank J,Sachsenhauser B. Experimental determination of the effective anionic charge density of polycarboxylate superplasticizers in cement pore solution[J]. Cement and Concrete Research,2009,39(1):1-5.
[8] Lange A,Hirata T,Plank J. The role of non-adsorbed PCE molecules in cement dispersion:Experimental evidence for a new dispersion mechanism[C]. Presented at the 10th International Conference on Superplasticizers and Other Chemical Admixtures, Prague, Czech Republic,October 28,2012.
[9] Yamada K,Ogawa S,Hanehara S. Controlling of the adsorption and dispersing force of polycarboxylate-type superplasticizer by sulfate ion concentration in aqueous phase[J]. Cement and Concrete Research,2001,31(3):375-383.
[10] Peng J H,Qu J D,Zhang J X,et al. Adsorption characteristics of water-reducing agents on gypsum surface and its effect on the rheology of gypsum plaster[J]. Cement and Concrete Research,2005,35(3):527-531.