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<p>The objective of this study is to understand the consolidated undrained stress–strain behavior of a “tunable” clay–polymer composite composed of kaolin and nonionic polyacrylamide under different confining stress, ionic concentration and pH conditions that promote changes in polymer molecule conformation (coiled, partially extended or extended). Based on the experimental results, the shear strength of the composite is controlled by the formation of higher-order face-to-face aggregated flocs under predicted partially extended conformation conditions and localized dilation under a low confining stress (100&#xa0;kPa). Under high confining stress (200&#xa0;kPa), the composite has a more contractive tendency compared to pure clay due to breakage of aggregates and flattened conformation of the polymer. The composite at partially extended conformation shows the thixotropic rearrangement of particles when overconsolidated. Both the coiled and extended conformations of polymer molecules promote apparent overconsolidation due to an increase in interparticle bonding and in contact area by forming large, aggregated flocs. However, the composite shear strength at coiled or extended conformation is mostly influenced by the conformation of polymer molecules. The clay–polymer composite is more responsive to change in pH and ionic concentration than pure clay and demonstrates the “tunability” of the composite. This experimental study sheds light on the link between polymer conformational changes and the mechanical behavior of clay–polymer composites.</p>

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Influence of Polyacrylamide Conformation on Shear Strength of a “Tunable” Clay–Polymer Composite

  • 期刊论文

  • 发表日期：

    2025年1月19日

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  • Bijoy K. Halder,
  • Angelica M. Palomino

摘要

The objective of this study is to understand the consolidated undrained stress–strain behavior of a “tunable” clay–polymer composite composed of kaolin and nonionic polyacrylamide under different confining stress, ionic concentration and pH conditions that promote changes in polymer molecule conformation (coiled, partially extended or extended). Based on the experimental results, the shear strength of the composite is controlled by the formation of higher-order face-to-face aggregated flocs under predicted partially extended conformation conditions and localized dilation under a low confining stress (100 kPa). Under high confining stress (200 kPa), the composite has a more contractive tendency compared to pure clay due to breakage of aggregates and flattened conformation of the polymer. The composite at partially extended conformation shows the thixotropic rearrangement of particles when overconsolidated. Both the coiled and extended conformations of polymer molecules promote apparent overconsolidation due to an increase in interparticle bonding and in contact area by forming large, aggregated flocs. However, the composite shear strength at coiled or extended conformation is mostly influenced by the conformation of polymer molecules. The clay–polymer composite is more responsive to change in pH and ionic concentration than pure clay and demonstrates the “tunability” of the composite. This experimental study sheds light on the link between polymer conformational changes and the mechanical behavior of clay–polymer composites.