Polyacrylamide-Treated Kaolin clay: A Fabric Study

Open Access
Author:
Kim, Sung ho
Graduate Program:
Civil Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Angelica Palomino, Thesis Advisor
  • Angelica M Palomino, Thesis Advisor
Keywords:
  • SEM
  • polymer
  • kaolinite
  • liquid limit
  • sedimentation
  • viscosity
  • fabric study
  • kaolin clay
  • polyacrylamide
  • microcomposite
  • nanocomposite
Abstract:
The field of surface-treated clays, especially polymer-treated clays, has been growing for the last a few decades, with a considerable number of studies conducted on the use of polymers as a clay-surface treatment. In spite of many studies on the behavior of clay-polymer systems at the level of particle-particle and particle-fluid interactions, fabric development over a wide range of solids content is poorly understood. The purpose of this study is to understand fabric development in a clay-polymer system, specifically kaolin-polyacrylamide systems over a wide range of solids content. Methodologies include sedimentation tests (low solids content), viscosity measurements (moderate solids content), and liquid limit measurements (high solids content), and are conducted to determine variation in fabric for kaolin-polyacrylamide systems at various concentrations, molecular weight and ionic types of polyacrylamide. Fabric development is verified using scanning electron microscopy (SEM). Fabric changes in sedimentation, viscosity, and liquid limit behavior in the presence of polyacrylamide corresponding to the change in the type of particle association are observed in SEM. Floc/aggregate size and density tend to increase with increasing polyacrylamide concentration, showing the formation of more larger, denser flocs. Final sediment height tends to decrease with an increase in polyacrylamide concentration, indicating denser particle associations (face-to-face) and verified with scanning electron microscopy. Viscosity tends to increase as polyacrylamide concentration increases, implying more flocculated/aggregated fabric formation. High molecular polyacylamides tend to induce a higher liquid limit with increasing concentration, demonstrating the formation of open flocculated structure. It is observed that the most likely particle association in the presence of polyacrylamide is face-to-face association by polymer bridges, which in turn results in a dense fabric. The molecular weight and concentration of polyacrylamide determines the fabric formation over a wide range of solids content. The polymer charge type impacts on the resulting fabric formation only at polymer concentration above the critical coagulation concentration. A relationship is found between polymer characteristics, solids contents, and micro-scale particle arrangement. This relationship is summarized in a series of fabric maps.