PB-g-PS胶乳改性水泥砂浆的性能

利用氧化还原引发体系,采用半连续乳液接枝共聚的方法合成了聚丁二烯接枝聚苯乙烯(PB-g-PS)接枝共聚胶乳,其中聚丁二烯(PB)与聚苯乙烯(PS)的质量比为70/30,50/50和30/70.在固定流动度为(175±5)mm,且在20℃水中养护6 d,然后在20℃,相对湿度为65%的空气中养护21 d的混合养护条件下,考察了聚灰比、聚丁二烯与聚苯乙烯的质量比对PB-g-PS胶乳改性水泥砂浆的水灰比、流动度、保水率、抗压和抗折强度以及吸水量的影响,并与羧基丁苯胶乳改性水泥砂浆进行了性能对比试验.结果表明:在一定掺量范围内,胶乳都具有良好的减水作用,能有效提高砂浆的保水性能,显著降低聚合物改性砂浆的毛细孔吸水率;加入聚合物对砂浆力学性能有重要影响,使其抗压强度总体降低,抗折强度部分提高,因此,PB-g-PS胶乳可以作为水泥改性剂使用.

Properties of PB-g-PS Latex-Modified Cement Mortars

Polybutadiene-graft-polystyrene(PB-g-PS)latexes were prepared via emulsion graft copolymeri-zation method using a redox initiator system,the mass ratios of the polybutadiene to styrene ranged from 70/30,50/50 to 30/70,and then the PB-g-PS latex was used to modify cement mortar.In the fixed flow of (175±5)mm,and under a mixed curing condition(6 d immersed in 20℃ water followed by 21 d at 20℃,RH=65%).The effects of mass ratios of polybutadiene to styrene and the polymer-cement ratios on the flow,water reduction effect,water retention rate,compressive and flexural strengths and water absorp-tion rate of PB-g-PS latex modified cement mortar were examined.then the performance of the carboxylSBR latex-modified cement mortar was compared.It has been show that the four kinds of latex-modified mortars has a good water-reducing effect,and water retention effect of modified mortars is improved in a certain range of polymer-cement ratio,capillary water absorption rate is markedly reduced in PB-g-PS la-tex.The mechanical properties of modified mortars will greatly be influenced by PB-g-PS latex.The com-pressive strength of the polymer modified mortar decreased,and the flexural strength of a portion polymer modified mortar increased.PB-g-PS latex can be incorporated into cement mortars as cement modifier.