Meso-Scale Behavior Characterization of "Tunable" Clay-Polymer Composites

“可调”粘土聚合物复合材料的细观尺度行为表征

• 批准号: 1266288
• 负责人: Angelica Palomino
• 金额: $ 17.03万
• 依托单位: University of Tennessee Knoxville
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1266288&HistoricalAwards=false
• 关键词: Meso; Scale; Behavior; Characterization; Tunable

Soils are natural materials. As such, their properties can vary greatly from location to location. This variability makes it difficult to predict or control the behavior of soil as a construction material. One approach to minimize this variability is to engineer a soil such that it performs in a predictable manner. This grant provides funding to investigate "tunable" clay-polymer composites in which the interparticle and/or interlayer spacings are controlled via a pH and ionic concentration-responsive polymer. This research will test the hypothesis that the pH- and ionic-concentration-induced manipulations previously observed at the particle level are also manifested at the meso-scale. The particular polymer used in this research is polyacrylamide, which is a widely available and inexpensive polymer often used for water treatment purposes. Meso-scale characterization of the clay-polymer composites will include measurement of swelling capacity; impact of repeated pH and ionic concentration cycling on hysteresis; changes in hydraulic conductivity with permeant pH and ionic concentration cycling; consolidation and shear wave velocity response under selected pH and ionic concentrations; and, shear strength under selected pH and ionic concentration conditions. The expected results from this work are: (1) a relationship between selected pH and ionic concentration environments and the degree of swell or shrink; (2) a relationship between selected pH and ionic concentration environments and response time of the material; (3) the composite response with selected pH and ionic concentration fluid cycling and any potential hysteresis; (4) demonstration of the "tunability" of the composites through hydraulic conductivity; (5) the relationship between the selected pH and ionic concentration environments and composite compressibility and shear wave velocity; and (6) shear strength properties of the composites when subjected to selected pH and ionic concentration conditions.If successful, the results of this work will contribute to the establishment of a novel field of research: engineered soils using functional polymers. The development of tunable polymer-clay composites whose properties can be modified to maximize their efficient use will improve the performance of barrier systems, clay liners, filters, and contaminant removal systems. These engineered soils can be designed for specific applications, and improve performance of structures such as filters, impervious barriers (water or gas), and contaminant barriers. In terms of their economic impact, the overall cost of producing these clay-polymer composite soils is likely to be relatively low since both the production method and the polymer are inexpensive. If improved chemical and hydraulic stability is shown, then application in waste barrier systems could lead to reduced leachate and infiltration contamination. Polymer-clay composites may also be a more sustainable material for stabilizing impervious system applications. Increasing the lifespan of such structures would reduce energy needs related to re-building failed systems.

土壤是天然物质。 因此，它们的属性可能因位置而异。 这种可变性使得难以预测或控制土壤作为建筑材料的行为。 最小化这种可变性的一种方法是设计土壤，使其以可预测的方式运行。 该基金提供资金用于研究“可调”粘土-聚合物复合材料，其中颗粒间和/或层间间距通过pH和离子浓度响应聚合物控制。 这项研究将测试的假设，pH值和离子浓度诱导的操纵先前观察到的颗粒水平也表现在中尺度。 在这项研究中使用的特定聚合物是聚丙烯酰胺，这是一种广泛使用的廉价聚合物，通常用于水处理目的。 粘土-聚合物复合材料的介观尺度表征将包括溶胀能力的测量;重复的pH和离子浓度循环对滞后的影响;渗透pH和离子浓度循环的水力传导率的变化;在选定的pH和离子浓度下的固结和剪切波速响应;以及在选定的pH和离子浓度条件下的剪切强度。 本工作的预期结果是：（1）选定的pH和离子浓度环境与溶胀或收缩程度之间的关系;（2）选定的pH和离子浓度环境与材料的响应时间之间的关系;（3）选定的pH和离子浓度流体循环和任何潜在滞后的复合响应;（4）通过水力传导性证明复合材料的“可调谐性”：（5）所选pH和离子浓度环境与复合材料压缩性和剪切波速之间的关系;和（6）当经受选定的pH和离子浓度条件时复合材料的剪切强度性能。如果成功，这项工作的结果将有助于建立一个新的研究领域：使用功能聚合物的工程土壤。 可调聚合物-粘土复合材料的开发，其性能可以被修改，以最大限度地提高其有效利用，将提高屏障系统，粘土衬里，过滤器和污染物去除系统的性能。 这些工程土壤可以针对特定应用进行设计，并改善过滤器，不透水屏障（水或气体）和污染物屏障等结构的性能。 就其经济影响而言，生产这些粘土-聚合物复合土壤的总成本可能相对较低，因为生产方法和聚合物都很便宜。 如果化学和水力稳定性得到改善，那么在废物屏障系统中的应用可能会减少沥滤液和渗透污染。 聚合物-粘土复合材料也可能是用于稳定防渗系统应用的更可持续的材料。 延长这些结构的使用寿命将减少与重建故障系统有关的能源需求。