Deformation of “tunable” clay-polymer composites

Responsive clay-polymer composites are the next step in the development of polymer-modified clay materials. It has been shown at the micro-scale that these materials respond to the surrounding pore fluid environment, resulting in an alteration in fabric. The purpose of this study is to investigate the impact of the responsive nature of these materials on the consolidation properties. Two composite types were selected to highlight the differences based on modified interparticle and interparticle/interlayer spacings: one made from a kaolinite and one from a montmorillonite. Each composite was made with polyacrylamide as the polymer. The clay-polymer composites were subjected to 1-D consolidation tests during which shear wave velocity was also measured. The pH of the saturating fluid was varied to promote composite response. Results show that the compressibility, compression index, and swelling index of the composite materials are greater than the untreated clay materials. Furthermore, these properties are pH-dependent for both types of composite materials and are consistent with the long-term conformational behavior of PAM. This apparent observation confirms that the behavior of the clay-PAM composites is controlled by the behavior of PAM. On the other hand, the shear wave velocities between the control and composite samples were not significantly different.