定向多孔水泥膜的制备与表征

发布时间：2018-06-08 16:20

本文选题：冷冻塑形 + 水泥膜　；参考：《中国海洋大学》2015年硕士论文

【摘要】：水泥是一种粉状水硬性无机胶凝材料,其与水充分搅拌后形成粘稠的浆料,在空气中或水中能够发生水化反应并且可以将砂石等粗细骨料粘结在一起,形成一种强度较高且能抵抗盐水腐蚀的常用无机材料一混凝土。水泥是通过加热煅烧粘土、石灰石或者其他类似生料混合物,并辅以适量外加剂制备而成的。由于制备水泥所需的原材料成本低廉,购置渠道广泛,这使得水泥成为了世界上成本最低的无机材料之一。与此同时,水泥基复合材料也是工业领域最重要和最多样的建筑材料。水泥浆料不仅具有良好的流变性能,且能够在一定的养护条件下发生水化反应,该反应产生众多的水化产物并成为水泥基复合材料的强度来源。与其他无机材料制备所需的工艺相比(烧结、煅烧),水泥的养护方法几乎没有成本与能耗,且工艺极为简便,是一种环保无污染的制备手段。多孔水泥基复合材料已被广泛的应用到各个领域之中,如人工骨骼替代,原油吸附,电磁干扰屏蔽,然而极少有报道涉及到关于制备定向多孔水泥基材料在分离领域中的应用。无机多孔材料的制备方法有许多,如发泡法、等静压法、造孔剂溶出法、固态粒子高温气化法等。其中造孔剂溶出法也被称作粒子溶出法,是通过造孔剂在溶液中的溶出的形式成孔,是一种制备三维多孔结构的有效方法,常用于骨组织工程的搭建；固态粒子烧结法即高温气化法,它是通过在高温下将造孔剂气化的方式造孔,是制备多孔陶瓷的一种常见方法；冷冻塑形作为一种新兴的制孔工艺,于近年来受到诸多科研人员的广泛关注。通过改变几个关键的制备要素,冷冻塑形法能够制得不同孔径大小及不同孔隙率范围的多孔材料,更因所制备的孔道具有定向均匀排列的特性,最终使多孔材料具有良好的力学性能以及可观的通量。本研究通过上述三种不同的制备方法研制了三种具有不同结构的多孔材料,通过对他们的结构与性能进行表征分析后发现,粒子溶出法所制备的多孔水泥基材料虽然具有可调控的孔隙率,但其所形成的孔道不连续,通孔比例较小,孔径尺寸较大(50μm～100μm),纯水渗透性实验也说明了其渗透性能较差。高温气化法制备的多孔水泥基材料虽然具有一定的孔隙率,但由于高温处理时水泥基材料极易受到破坏,且致孔剂(淀粉)在气化后所形成的孔道分布不均匀,孔道连续性较差,纯水渗透性实验也证明其渗透性能极差。冷冻塑形工艺是一种制备具有定向孔道的水泥基复合多孔材料(水泥膜)的有效方法。该实验通过球磨将水或叔丁醇,有机粘结剂分散剂,硅酸盐水泥充分混合搅拌均匀制得稳定的水泥基混合浆料,通过冷冻塑形的方法将该浆料定向冷冻为冻坯,随后将其置于冷冻干燥机内使造孔剂挥发完全以得到素坯,最终使多孔水泥基素坯在一定养护条件下充分反应得到定向多孔水泥基材料。本实验研究了水泥膜的各项性能与制备条件之间的关系,同时利用光学显微镜、扫描电子显微镜、压汞仪、X射线衍射仪、抗压强度测试仪、氮气吸附仪、紫外吸收光谱仪等仪器设备对制备的水泥膜结构性能进行表征,最后利用自制膜评价仪对水泥膜的渗透性能及分离性能做了详细研究。实验结果表明：冷冻塑形法成功的将水泥基复合材料制备成新型的定向多孔水泥膜：冷冻温度、浆料固含量、养护周期都对水泥膜的结构性能造成了不同的影响；孔道尺寸随着冷冻温度的下降、固含量的增加而减小,反之亦然;孔隙率随着冷冻温度的上升、固含量的减少而增加,反之亦然：由叔丁醇作为造孔剂制备所得的水泥膜在操作压力为0.2MPa时,对牛血清蛋白(BSA)的截留率达到74.8%,通量能保持在400 L·m-2·h-1到500 L·m-2·h-1。
[Abstract]:Cement is a hard powdery inorganic cementitious material, which is stirred with water to form a viscous slurry, which can be hydrated in the air or in water and can bind the coarse and fine aggregate, such as sand and stone, to form a concrete material with high strength and resistance to brine corrosion. The cement is calcined by heating. A mixture of clay, limestone, or other similar raw material, which is made up with an appropriate amount of admixture, is made up of an appropriate amount of admixture. Due to the low cost of the raw materials needed to prepare the cement and the wide channel of purchase, the cement has become one of the lowest cost inorganic materials in the world. At the same time, water mud matrix composites are also the most important and most important in the industrial field. The cement paste not only has good rheological properties, but also can produce hydration reaction under certain curing conditions. This reaction produces many hydrated products and becomes the strength source of cement based composites. Compared with other inorganic materials, the curing method of cement is almost no better than the other processes needed for the preparation of inorganic materials. The cost and energy consumption, and the process is very simple, is a kind of environmentally friendly and non pollution preparation means. Porous cement based composites have been widely used in various fields, such as artificial bone replacement, crude oil adsorption, electromagnetic interference shielding, but few reports involve the application of the preparation of directional porous cement-based materials in the field of separation. There are many methods for preparing inorganic porous materials, such as foaming, isostatic pressure, pore solution dissolution, solid particle high temperature gasification, etc., in which the dissolution method of pore making agent is also called particle dissolution method. It is an effective method to prepare three-dimensional porous structure by the form of pore forming agent in solution. It is often used in bone tissue engineering. The solid particle sintering method, the high temperature gasification process, is a common method for preparing porous ceramics by gasification of pore forming agents at high temperature. As a new hole making process, freezing molding has been widely used by many researchers in recent years. By changing several key preparation factors, freezing is frozen. The molding method can produce porous materials with different pore size and different porosity range, and the porous material has the characteristic of directional and uniform arrangement, and finally makes the porous material have good mechanical properties and good flux. In this study, three kinds of porous materials with different structures were developed by the three different preparation methods mentioned above. Material, after characterization and analysis of their structure and properties, it is found that the porous cement based material prepared by the particle dissolution method has a controllable porosity, but its pore channel is discontinuous, the pore size is small and the pore size is larger (50 to 100 m to 100 mu). The permeability test of pure water also shows that its permeability is poor. Although the porous cement based material prepared by gasification has a certain porosity, the cementitious material is easily damaged due to high temperature treatment, and the pore distribution of the pore agent (starch) is not uniform after gasification, and the continuity of the pore is poor. The permeability experiment of pure water shows that the permeability is very poor. The cryopreservation process is a kind of system. An effective method for preparing cement based composite porous material (cement film) with a directional channel. The experiment is made by ball milling to produce a stable cement based mixture of water or TERT butanol, organic binder dispersant and Portland cement. The slurry is frozen into a freeze-blank by the method of freezing and shaping, and then it is placed. In the freeze dryer, the pore forming agent is volatilized completely to get the plain billet, and the porous cement base billet is finally reacted to the porous cement-based material under certain curing conditions. The relationship between the properties of the cement film and the preparation conditions is studied in this experiment. At the same time, the optical microscope, scanning electron microscope, mercury injection instrument and X ray are used. Diffractometer, compressive strength tester, nitrogen adsorption apparatus, ultraviolet absorption spectrometer and other instruments and equipment to characterize the structure and properties of the prepared cement film. Finally, the permeability and separation properties of the cement film were studied in detail by the self-made membrane evaluator. The experimental results showed that the cold plastic method successfully prepared the cement matrix composite. The new directional porous cement film: freezing temperature, slurry solid content and curing period have different effects on the structure and properties of the cement film. The pore size decreases with the decrease of freezing temperature, the increase of solid content, and vice versa; the porosity increases with the rise of freezing temperature and the decrease of solid content, and vice versa: vice versa. The retention of bovine serum protein (BSA) is 74.8% when the operation pressure is 0.2MPa, and the flux can be maintained at 400 L. M-2. H-1 to 500 L. M-2. H-1.
【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

【相似文献】