摘要
利用麦芽糊精合成出新单体麦芽糊精丙烯酸酯(ADE),然后通过自由基聚合将其接枝到减水剂分子上合成改性聚羧酸减水剂,并利用红外光谱表征了ADE和改性聚羧酸减水剂的合成,同时探究了聚羧酸减水剂的最佳合成条件。结果表明,当反应温度为70℃、反应时间(滴加时间)为2.5 h、引发剂质量分数为1.4%、甲基烯丙基聚氧乙烯醚(TPEG)和丙烯酸(AA)与ADE的物质的量比为1∶3∶1.2时,合成出的改性聚羧酸减水剂对水泥的分散和保持性能最好。同时通过与市售减水剂的性能对比,发现麦芽糊精改性聚羧酸减水剂对水泥的的分散和保持性能良好,后期也可以显著提高混凝土的强度。
A new monomeric maltodextrin acrylate(ADE) was synthesized by using maltodextrin,and then it was grafted onto the water reducing agent molecule by free radical polymerization to synthesize a modified polycarboxylate water reducing agent,and the infrared spectrum was utilized.The successful synthesis of maltodextrin acrylate and modified polycarboxylate superplasticizer were characterized,and the optimal synthesis conditions of modified polycarboxylate superplasticizer were explored.The results showed that when the reaction temperature was 70 ℃,the reaction time(dropping time) was 2.5 hours,the amount of the initiator was 1.4%,and the molar ratio of methallyl polyoxyethylene ether,acrylic acid and ADE was 1∶3∶1.2,the synthesized modified polycarboxylic acid water reducing agent had the best dispersion and retention performance for cement.At the same time,by comparing with commercially available water reducing agents,the maltodextrin modified polycarboxylate water reducing agent not only had good dispersion and retention properties,but also improved the strength of concrete significantly in the later stage.
引文
[1] 张新民,冯恩娟,徐正华,等.聚羧酸类减水剂的分子设计与结构性能关系[J].化工进展,2008,27(6):913-916.
[2] 卫爱民,韩得丰.聚羧酸系混凝土高效减水剂的作用机理及合成工艺现状[J].混凝土,2008,8:69-72.
[3] PENG X Y,YI C H,DENG Y H,et al.Synthesis and evaluation of polycarboxylate-type superplasticizers with different carboxylic contents used in a cement system[J].Int J Polym Mater,2011,60(12):923-938.
[4] 何燕,张永娟,王义廷,等.含不同官能团聚羧酸减水剂的吸附-分散性能[J].同济大学学报,2017,45(2):244-248.
[5] 倪涛,刘昭洋,程文强,等.一种缓释型聚羧酸减水剂的合成与性能表征[J].新型建筑材料,2016,23(7):7-10.
[6] 姜玉,庞浩,廖兵.聚醚侧链聚羧酸类减水剂的结构及应用性能[J].化工进展,2008,27(5):733-735.
[7] YU B B,ZENG Z,REN Q Y,et al.Study on the performance of polycarboxylate-based superplasticizers synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization[J].J Mol Struct,2016,1120(17):1-9.
[8] 李崇智,祁艳军,陈家珑,等.聚羧酸系减水剂在高性能混凝土中的应用研究[J].新型建筑材料,2008,23(6):57-62.
[9] 尤启俊,陆酉扩,仲以林,等.聚羧酸类高效减水剂应用中的问题浅析[J].商品混凝土,2008,1:5-6.
[10] 张照华.聚羧酸系高性能减水剂在自密实混凝土施工中的应用[J].建筑科学,2008,24(3):118-120.
[11] LI Y W,ZHENG J,GUO H L,et al.Preparation and application of new polycarboxylate superplasticizers with mild retarding performance based on monovinyl beta-cyclodextrin monomer[J].J Disper Sci Technol,2015,36(3):369-376.
[12] 杨玉玲,游远,陈银基,等.米淀粉为基质的脂肪替代品中麦芽糊精结构研究[J].中国粮油学报,2013,28(5):6-10.