Abstract

Surfactants have been used to modulate mechanical properties and hydration of calcium sulfate hemihydrates or other cement-like material, especially to improve the properties of cheap materials. In gypsum industry, β-Hemihydrate (β-H) costs less than the α-hemihydrate but presents lower mechanical strength after hydration. In this study, a group of polysulfonates was designed and synthesized to investigate their structure-performance relationship in hydration of β-H and properties of the gypsum plaster. It was found that the hydration of β-H can be modulated by changing the hydrophilic side chain of the polysulfonates, which endowed the gypsum with differential mechanical strength and water absorption. The sodium alkenyl methyl polyoxyethylene ether amide vinyl/ally sulfonate offered the β-H gypsum highest water absorption, retarded hydration and enhanced mechanical strengths by forming compacter rod crystals. The mechanical strength and water absorption of the gypsum were not in direct proportion to hydrophilicity of the polysulfonates and the molar fraction of sulfonic groups, but related to their McGowan’s HLB values. When the HLB values were below 15, the water absorption of β-H gypsum induced by the polymers increases with the increasing HLB values of the polymers.

摘要

表面活性剂已被用于调节硫酸钙半水合物或其他水泥类材料的机械性能和水合作用，特别是用于改善廉价材料的性能。在石膏工业中，β-半水合物 ( β -H) 的成本低于α-半水合物，但水化后的机械强度较低。在这项研究中，设计并合成了一组聚磺酸盐，以研究它们在β -H 水化过程中的结构-性能关系和石膏灰浆的性能。发现β的水合-H可以通过改变聚磺酸盐的亲水侧链来调节，从而赋予石膏不同的机械强度和吸水性。烯基甲基聚氧乙烯醚酰胺乙烯基/烯丙基磺酸钠为β- H 石膏提供了最高的吸水率、延迟的水合作用并通过形成更致密的棒状晶体来增强机械强度。石膏的机械强度和吸水率与聚磺酸盐的亲水性及磺酸基团的摩尔分数不成正比，而与其麦高文HLB值有关。当HLB值小于15时，聚合物引起的β -H石膏吸水率随着聚合物HLB值的增加而增加。