Role of Clay-Solvent Inter and Intraparticle Interactions on Swelling Characteristics of Montmorillonite Nano-Meso-Micro
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Role Of Clay-Solvent Inter And Intraparticle Interactions On Swelling Characteristics Of Montmorillonite Nano-Meso-Micro Scale Particulate Systems Dinesh R. Katti, Kalpana S. Katti and Vijayakumar Shanmugasundaram Civil Engineering, CIE 201, North Dakota State University, Fargo ND 58105, USA ABSTRACT This paper deals with fundamental molecular issues related to macroscopic mechanical properties of nano-meso-microscale montmorillonite clay particulate systems. Molecular interaction of high aspect montmorillonite particles with solvents has large influence on resulting swelling characteristics in clays consisting of montmorillonite. A new controlled uniaxial swelling (CUS) cell is designed which allows a simultaneous measurement of swelling and swelling pressure in addition to ease of removal of undisturbed samples for electron microscopic and fourier transform infrared spectroscopic investigations. Our work shows that the swelling behavior of montmorillonite directly results from breakdown of large particles to smaller nano and meso scale particles with increased water incorporation in the interlayers. The Si-O vibration band regions of the montmorillonite spectra obtained at controlled amounts of swelling from 0100% (where 0% swelling is defined as fully saturated samples under no volume change) show changes in band shape, intensity, and positions resulting from increased H-bonding in the interlayers and surface of montmorillonite particles. In addition, orientation dependant microattenuated total reflectance (ATR) spectroscopic investigations are also conducted on the controlled swelled samples. Our results indicate that the reduced particle size with increased swelling is related to increased misorientation of the montmorillonite platelets. The relationship between molecular interactions microstructure and macroscopic response (swelling and swelling pressure) is the key to development of novel nanocomposite systems based on montmorillonite with tailored properties. INTRODUCTION The swelling response of montmorillonite clay and corresponding development of swelling pressure when swelling is restrained is a result of fairly complex clay-water interactions between particles and within the particles itself. The understanding and quantitative modeling of these fundamental interactions are extremely important for modeling these systems. The relationship between molecular interactions, microstructure and macroscopic response (swelling and swelling pressure) is the key to development of novel nanocomposite systems based on montmorillonite with tailored properties. Analytical electron microscopy techniques offers the scanning electron microscope (SEM) as a useful tool for the study of microstructural changes in clays with high spatial resolution. Vibrational spectroscopy yield useful information about hydration characteristics, interlayer cations and moisture content in clays. The excitation of a purely vibrational transition by infrared light obeys the selection rules for electric dipole transitions as described by classi
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