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| 基于阴离子水性聚氨酯的化学固沙作用及过程研究 | |
| 其他题名 | Study on the interaction and processes of chemical sand stabilization based on anionic water-borne polyurethane |
| 臧运晓 | |
| 出版年 | 2017 |
| 学位类型 | 博士 |
| 导师 | 刘白玲 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 荒漠化问题是影响当今世界最为严重的社会环境问题之一，其不但引起一系列土地减产、经济衰退等社会经济问题，还与全球的气候变化、生物多样性损失构成恶性循环。为全人类的福祉计，防治荒漠化的工作已经在世界范围内展开，并开发出许多对抗荒漠化的策略和技术。风蚀荒漠化是影响面积最大、危害最为严重的荒漠化类型，而化学固沙在风蚀荒漠化的防治当中所表现出的见效快、人工成本低、促进植物生长等优点使其获得了广泛关注。在以往的固沙研究中，过于偏重对固沙效果的考察，缺乏对其涉及的相关物理化学过程的研究，致使对化学固沙的理解不够深入，暴露出许多问题。目前对固沙机理的研究多停留于形貌观察和理论推断，缺乏更具针对性的研究方法和检测手段。总体来看，当前研究对于化学固沙所涉及的科学问题尚缺乏提炼和对应研究，由此导致的理论高度的缺失也造成了在固沙材料开发方面的盲目性。针对上述问题，本论文开展了以下相应的研究：首先以具有代表性分子结构的一系列阴离子水性聚氨酯分散体为研究载体，从形貌观察、受力分析、表面元素分析及迁移行为考察等角度，探探讨了固沙性能、沙体结构、材料性能三者之间的关系，并对材料与沙的相互作用、作用的方式及过程等基本的土力学和物理化学问题进行了提炼及研究。同时，所制备的水性聚氨酯分散体也有助于解决聚氨酯固沙剂本身存在的产品形态与便捷性的矛盾，对于以往水性聚氨酯固沙应用研究不够深入的问题，也有良好改善。本论文研究内容主要由以下四个部分组成：1．采用自乳化法制备了一系列具有代表性分子结构的阴离子水性聚氨酯分散体。考察了中和含量、多元醇分子量以及异氰酸酯指数对分散体粒径、ζ电位、机械性能、外观以及稳定性等方面的影响。本部分工作的目的在于为后续的固沙性能考察、机理研究提供性能具备变化梯度的分散体。2．以自制的阴离子水性聚氨酯分散体为固沙材料进行了化学固沙实验，在较为全面考察包括固结层抗风蚀性、沙模抗压强度、固结层耐水性、固结层保水性、沙模热稳定性、沙模冻融稳定性、固沙材料对微生物的影响、固结层对种子出芽的影响等方面固沙性能的基础上，着重对固结强度、保水性能与材料性能、沙土结构的关系，采用形貌分析、强度测试、受力分析结合分子结构分析等多种方式进行了研究，建立了较为明晰的材料性能与固沙性能的对应关系。3．基于EDS定量分析方法，对采用阴离子水性聚氨酯分散体进行化学固沙后的沙粒表面金属离子出现的变化进行了分析，通过建立具象的网格模型及抽象的矩阵表达式，对变化的多样化原因进行了解释，并结合理论分析和凝胶行为等对变化机理进行了说明。这部分工作为固沙材料与沙粒的界面相互作用提供了佐证。4．在第2部分工作中，我们发现阴离子水性聚氨酯分散体在沙土中的堆积效果影响不但影响其固结效果，还左右其保水性能。为此，设计渗透实验装置研究了决定分散体在沙土中堆积效果的渗透过程，研究所发现的胶粒和水分的非同步化迁移解释了不同结构固结层的形成原因，加深了对固结层形成过程的理解。所建立的方法可用于其他类似高分子分散体的渗透行为的研究。 |
| 英文摘要 | Desertificaiton is nowadays one of the most serious environmental problems. It not only causes a series of socio-economic problems such as reduction of land production and economic recession, but also forms vicious circles with climate change and biodiversity loss all over the world. For the sake of human well-being in the world, efforts combating desertification have been taken worldwidely and lots of stragedis and technologies have been developed.Sandy desertification, which is characterized by wind erosion, is the most widespread and damaging type of desertification. Chemical sand stabilization (CSS) has drawn increasing attentions due to its advantages in combating desertification, such as quick construction, low labor cost, and the improvement of the growing condition for plant. However, overmuch investigations have been carried out on the application performance in the former studies on CSS, and there is lack of reseach on the basic physicochemical processes. This results in some questions such as inadequate understanding on CSS. Most of the discussion on the mechanism of CSS are based on morphology observation and theoretical judgement, lacking of specific investigation methods and test technologies. In general, the field of CSS are in need of abstracting basic scientific questions on CSS and relative study. This situation is also the reason of the blindness in developing new sand-stabilizing material. This dessertation is to introduce the work carried out aiming at the problems above. First, a series of anionic water-borne polyurethane dispersions (APUDs), which have representable molecular structures, were prepared to be the carrier of the study on CSS. Second, the relationship among sand-tabilizing properties, sand structure, and APUD properties was discussed from multiple perspectives of morphology investigation, force analysis, appareance elements analysis, and migration behavior. Third, the basic questions related to soil mechnics and physicochemical processes, including the interaction and its process between sand and APUD, were extracted and studied. Besides, the APUDs themselfves were help to resolve the conflicts between the product form and the convenience demand in application, and to impulse deeper investigation on polyurethane as sand-stabilizing material.The study is composed of four parts as following: 1. A series of APUDs with representable molecular structure were prepared via self-emulsification method. The influence of the content of neutralized hydrophilic extender, molecular weight of polyols, and isocyanate index on the particle size, ζ potential, mechanical property, appareance, and stability was investigated. This part of work was carried out to provide dispersions with changing gradient in properties for the next studies on the CSS performance and mechanisms. 2. Chemical sand stabilizing tests were taken with the APUDs prepared in the former part. A comprehensive investigation was carried out, involving anti-wind erosion property of the consolidated layer, compressive strength of the sand molds, water resistance of the consolidated layer, water containing capacity of the consolidated layer, thermal stability and freeze-thaw stability of the sand molds, influence on the microorganism, and influence on seed germination. The relationship among the consolidating strength, water containing capcity, APUD properties, and the sand structure was emphasized and studied with multiple methods including morphology analysis, strength test, force analysis, and molecular compositon analysis. The correspondce between CSS performance and APUD properties was concluded.3. Base on the EDS quantitative analysis, the changes of the metallic cations on the appareance of treated sand was analized. The figurative grid model and the abstract matrix expression were fouded to explain the diversity of the changes. The mechanisms on the changes were illustrated after theoretical analysis and gelation behavior analysis of the APUDs. This part provides support for the interfacial interaction between sand and the sand-stabilizing material.4. In the 2nd part, it was found that the accumulation effect of the APUDs in sand could affect not only the consolidating strength but also the water containing capacity. Therefore, the infiltration processes of APUDs in sand, which determined the accumulation effect, were investigated with a set of self-designed equipment. The founded asynchronous migration of APU particles and water revealed the reason of different consolidated layer structure. The founded method also proved a choice for the study of the infiltration behavior of other polyer dispersions. |
| 中文关键词 | 化学固沙 ; 阴离子水性聚氨酯 ; EDS定量分析 ; 金属离子吸附 ; 高分子分散体渗透 |
| 英文关键词 | chemical sand stabilization anionic water-borne polyurethane EDS quantitative analysis metallic ions adsorption polymer dispersion infiltration |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 高分子化学与物理 |
| 来源机构 | 中国科学院成都有机化学研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287827 |
| 推荐引用方式 GB/T 7714 | 臧运晓. 基于阴离子水性聚氨酯的化学固沙作用及过程研究[D]. 中国科学院大学,2017. |
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