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.

土壤是天然材料。 因此，它们的属性在位置之间的差异很大。 这种可变性使得很难预测或控制土壤作为建筑材料的行为。 一种最小化这种可变性的方法是设计土壤以可预测的方式执行。 该赠款提供了研究“可调节”粘土聚合物复合材料的资金，其中颗粒和/或层间间距通过pH和离子浓度响应聚合物控制。 这项研究将检验以下假设：先前在粒子水平上观察到的pH和离子浓度诱导的操纵也在中尺度表现出来。 这项研究中使用的特定聚合物是聚丙烯酰胺，这是一种广泛可用且廉价的聚合物，通常用于水处理用途。 粘土聚合物复合材料的中尺度表征将包括测量肿胀能力；反复的pH和离子浓度循环对滞后的影响；液压电导率随渗透性pH和离子浓度循环的变化；在选定的pH和离子浓度下的合并和剪切波响应；并且，在选定的pH和离子浓度条件下的剪切强度。 这项工作的预期结果是：（1）选定的pH和离子浓度环境与膨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）具有选定的pH和离子浓度流体循环和任何潜在滞后的复合反应； （4）通过液压电导率证明复合材料的“可调性”； （5）选定的pH和离子浓度环境与复合可压缩性和剪切波速度之间的关系； （6）复合材料的剪切强度特性在经过选定的pH和离子浓度条件下进行。如果成功，这项工作的结果将有助于建立新的研究领域：使用功能性聚合物进行工程的土壤。 可以修改其性能以最大程度地利用其性能的可调聚合物粘土复合材料的开发将改善屏障系统，粘土衬里，过滤器和污染物去除系统的性能。 这些工程的土壤可以用于特定应用，并改善结构的性能，例如过滤器，不透水障碍（水或气体）和污染物障碍。 就其经济影响而言，生产这些粘土聚合物综合土壤的总体成本可能相对较低，因为生产方法和聚合物都便宜。 如果显示了改善的化学和液压稳定性，则在废物屏障系统中的应用可能导致渗滤液和浸润污染减少。 聚合物粘土复合材料也可能是稳定不透水系统应用的更可持续的材料。 增加此类结构的寿命将减少与重建失败系统有关的能源需求。