氯氧镁水泥耐水复合改性的研究

发布时间：2018-02-27 21:25

本文关键词： 氯氧镁水泥磷酸聚合物耐水性复合改性　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：氯氧镁水泥(MOC)属于气硬性胶凝材料,具有早强、高强、快凝、耐磨、耐腐蚀、防火抗冻、粘结力强、低碱、加工性能好等一系列优点,但同时也存在不耐水、易吸潮返卤、变形、吸水后强度严重下降等许多缺陷。所以氯氧镁水泥在工程应用方面具有很大的局限性,目前主要用于制备地板材料、包装材料、装饰材料等非承重材料,以及耐火制品、磨具磨料、代木制品等。为解决氯氧镁水泥耐水性差的问题,本论文提出利用磷酸与高分子聚合物复合改善氯氧镁水泥耐水性的方法,以水化产物表面形成的磷酸镁和耐水聚合物膜层的结构与形成机理为研究对象,结合XRD、SEM和FTIR等微观测试方法,研究磷酸-MOC、聚合物-MOC和磷酸-聚合物-MOC体系的耐水机制,初步探讨磷酸、聚合物复合改性的改性机理,为氯氧镁水泥耐水性的有效改善和广泛应用提供理论依据和技术支撑。本论文主要得出以下研究结论:(1)磷酸可显著提高氯氧镁水泥的耐水性,但存在缓凝作用,磷酸掺量一般选择为1%。通过磷酸溶液处理空白试样表面的方法,发现表面生成的MgHPO_4·3H_2O可促进试样耐水性的提高,这是由于[PO_4]~(3-)与Mg~(2+)生成的难溶性磷酸盐附着在晶相表面,阻止或抑制水化产物的水解,从而提高耐水性。(2)单掺苯丙乳液不能改善氯氧镁水泥的耐水性,甚至使耐水性变差,这是由于苯丙乳液中的低聚物不能自发吸附在水化产物晶相表面,无法形成有效的耐水保护膜。但是复掺磷酸钠与苯丙乳液可有效提高氯氧镁水泥的耐水性,当复掺1%磷酸钠与8%苯丙乳液时软化系数可达到0.93。在磷酸根离子([PO_4]~(3-))存在的条件下,[PO_4]~(3-)与Mg~(2+)相结合吸附在水化产物表面,使表面呈现出极强的负电性,诱导体系中的胶体颗粒迁移并吸附到水化产物表面上,形成均匀稳定的耐水薄膜,从而提高氯氧镁水泥的耐水性能。(3)常温固化的热固性树脂可在一定程度上提高水泥的耐水性,且复掺磷酸与树脂效果更佳。本实验研究了不饱和聚酯树脂、乙烯基树脂、氨基树脂,发现氨基树脂的改性效果最佳,且液态氨基树脂的改性效果要优于粉状氨基树脂,当复掺1%磷酸与10%氨基树脂时,水泥的7d软化系数能达到1左右。当磷酸存在时,氨基树脂易在水化产物表面形成防水膜层,对5相晶体的保护效果较好。
[Abstract]:Magnesium oxychloride cement (MOC) is a kind of gas-hard cementing material. It has a series of advantages, such as early strength, high strength, quick solidification, wear resistance, corrosion resistance, fire resistance, strong adhesion, low alkali, good processability, etc. So magnesium oxychloride cement has great limitations in engineering application. At present, it is mainly used in the preparation of floor materials, packaging materials, decorative materials and other non-load-bearing materials, as well as refractory products. In order to solve the problem of poor water resistance of magnesium oxychloride cement, a method of improving water resistance of magnesium oxychloride cement with phosphoric acid and polymer was put forward. The structure and formation mechanism of magnesium phosphate and water-resistant polymer coatings formed on the surface of hydrated products were studied. The mechanism of water resistance of phosphoric acid (Phosphoric acid), polymer (MOC) and phosphoric acid-polymer-MOC (PPO-MOC) systems was studied by means of XRD-SEM and FTIR. The modification mechanism of phosphoric acid and polymer composite modification was discussed. The main conclusions of this paper are as follows: 1) Phosphoric acid can significantly improve the water resistance of magnesium oxychloride cement, but it has retarding effect. The content of phosphoric acid is generally chosen as 1. By treating the surface of blank sample with phosphoric acid solution, it is found that MgHPO_4 路3H _ 2O generated on the surface can improve the water resistance of the sample, which is due to the adhesion of insoluble phosphate formed by [PO_4] / Mg~(2) to the surface of crystalline phase. The water resistance of magnesium oxychloride cement can not be improved by preventing or inhibiting the hydrolysis of hydration products, thereby improving the water resistance of magnesium oxychloride cement. This is because the oligomer in the styrene-acrylic emulsion can not be spontaneously adsorbed on the crystalline surface of the hydration product and can not form an effective water-resistant protective film, but the co-doped sodium phosphate and styrene-acrylic emulsion can effectively improve the water resistance of magnesium oxychloride cement. When mixed with 1% sodium phosphate and 8% styrene-acrylic emulsion, the softening coefficient can reach 0.93. Under the condition of the presence of [PO_4] ([PO_4] ~ (3-O)), [PO_4] ~ (3) and Mg~(2) are adsorbed on the surface of the hydration product, which makes the surface of the hydrated product exhibit very strong negative electric properties. The colloidal particles in the system were induced to migrate and adsorbed onto the surface of the hydration products to form a uniform and stable water resistant film, thus improving the water resistance of magnesium oxychloride cement. 3) the thermosetting resin cured at room temperature could improve the water resistance of the cement to a certain extent. In this experiment, unsaturated polyester resin, vinyl resin and amino resin were studied. It was found that the modification effect of amino resin was the best, and the modification effect of liquid amino resin was better than that of powder amino resin. When mixed with 1% phosphoric acid and 10% amino resin, the softening coefficient of cement can reach about 1 in 7 days. In the presence of phosphoric acid, the amino resin can easily form a waterproof film on the surface of the hydrated product, and the protective effect of the 5-phase crystal is better.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ172.1

【参考文献】