偶联剂对PB-g-PS胶乳改性水泥砂浆性能的影响

Effects of Coupling Agent on the Performances of PB-g-PS Latex Modified Cement Mortar

重量比为50/50的聚丁二烯接枝聚苯乙烯(PB-g-PS)胶乳用于改性水泥砂浆。考察了聚合物对水泥重量比(聚灰比)和偶联剂含量对胶乳改性水泥砂浆的流动度、抗压和抗折强度以及吸水量的影响。研究表明:改性砂浆的流动度随聚灰比和偶联剂含量的增加而增加;胶乳和适量偶联剂能降低改性砂浆的毛细孔吸水量;胶乳的加入使改性砂浆的抗压强度降低,随聚灰比的增加,改性砂浆抗折强度呈下降趋势,偶联剂的加入极大地改善了砂浆的力学性能。利用SEM观察到改性砂浆的结构更加致密,界面结构得到改善,观察到了聚合物膜的纤维状和互穿网络结构。利用DSC对改性砂浆样品进行了分析,结果表明:偶联剂对水泥水化和晶形转变具有重要影响。

As weight ratio of 50/50,the polybutadiene-grafting-polystyrene （PB-g-PS） latex is used to modify the cement mortar.The effects of the polymer-cement ratio and coupling agent content on fluidity,compressive strength,flexural strength and water absorption of latex modified cement mortar are discussed.As a result,the fluidity of modified cement mortar is increasing as the polymer-cement ratio and the content of coupling agent increased.The latex and proper content of coupling agent can decrease the water absorption of capillary pores of modified mortar.The compressive strength of modified mortar is decreased when adding the latex,and as the polymercement ratio increasing,the flexural strength of modified mortar presents a downtrend,however,the coupling agent can improve the mechanical properties of modified mortar obviously.The structure of modified mortar is more compact,and the interface structure is improved observed by SEM,and the fibrous and interpenetrating network structures of polymer membrane have been observed.The DSC testing for modified mortar shows that the coupling agent has great influences on cement hydration and crystal form change.