聚丙烯酰胺乳液对脱硫建筑石膏性能的影响

采用高分子聚合物——聚丙烯酰胺乳液改性脱硫建筑石膏,提高其力学与防水性能。研究聚丙烯酰胺乳液掺量、分子量对脱硫建筑石膏物理力学性能和防水性能的影响,采用X-射线衍射仪XRD)、扫描电子显微镜SEM)对脱硫建筑石膏水化微观结构进行表征。结果表明:当掺入聚丙烯酰胺乳液浓度2%、掺量为脱硫建筑石膏的1%、分子量300万时,软化系数由0.34提高到0.69,水中浸饱24后的抗压强度由4.9MPa提高到6.1MPa,使用分子量为300万聚丙烯酰胺配制的乳液对脱硫建筑石膏进行改性效果优于分子量为500万的改性效果。聚丙烯酰胺乳液对脱硫建筑石膏水化的作用机理是:一方面与脱硫石膏中Ca2+相互作用生成化合物,填充于脱硫建筑石膏水化产物二水硫酸钙晶体之间的空隙中,另一方面聚丙烯酰胺分子将脱硫建筑石膏颗粒包裹起来,阻碍与水发生水化反应。

Effects of Polyacrylamide Emulsion on Properties of Desulfurized Building Gypsum

The waterproofness of desulfurized building gypsum had been improved by polyacrylamide(PAM) emulsion.The effects of dosage and molecular weight of PAM emulsion on the physical mechanical properties and waterproofness have been researched and X-ray diffractometry(XRD),scanning electron microscopy(SEM) have been employed to determine the phase composition of the material.The results showed that softening coefficiency of desulfurized building gypsum increased form 0.34 to 0.69,the compressive strength in water 24 h increased from 4.9MPa to 6.1 MPa.The effect of PAM emulsion modification prepared by PAM with molecular weight of 3 million on desulfurized building gypsum is better than that of with molecular weight of 5 million.The mechanism of PAM on desulfurized building gypsum was that PAM reacts with the Ca2+ cations produced hydration of desulfurized building gypsum to form the ionic compounds acting as a filler and reinforcement in the porosity of desulfurize building gypsum,and also PAM covered the surface of desulfurized building gypsum particles to prevent the crystallization of CaSO4·2H2O.