Nanocomposites refer to the materials in which the defining characteristic size of
inclusions is in the order of 10-100nm. There are several types of nanoparticle inclusions
with different structures: metal clusters, fullerenes particles and molybdenum selenide,
Our research focus is on polymer nanocomposites with inorganic clay particles as
inclusions, in particular we used sodium montmorillonite polymer nanocomposite.
In our study, modeling and simulations of sodium montmorillonite (Na+-MMT) is
currently being investigated as an inorganic nanocomposite material. Na+-MMT clay
consists of platelets, one nanometer thick with large lateral dimensions, which can be
used to achieve efficient reinforcement of polymer matrices. This nanocomposite has
different applications such as a binder of animal feed, a plasticizing agent in cement,
brick and ceramic, and a thickener and stabilizer of latex and rubber adhesives.
In this study, sodium montmorillonite called Na+-MMT structure is built with the
bulk system and the layered system which includes from 1 to 12 layers by using Crystal
Builder of Cerius2. An isothermal and isobaric ensemble is used for calculation of
thermodynamic properties such as specific heat capacities and isothermal expansion
coefficients of Na+-MMT. A canonical ensemble which holds a fixed temperature,
volume and number of molecules is used for defining exfoliation kinetics of layered
structures and surface formation energies for Na+-MMT layered structures are calculated
by using a canonical ensemble. Mechanical properties are used to help characterize and
identify the Na+-MMT structure. Several elastic properties such as compliance and
stiffness matrices, Young's, shear, and bulk modulus, volume compressibility, Poisson's
ratios, Lamé constants, and velocities of sound are calculated in specified directions. Another calculation method is the Vienna Ab-initio Simulation Package (VASP). VASP
is a complex package for performing ab-initio quantum-mechanical calculations and
molecular dynamic (MD) simulations using pseudopotentials and a plane wave basis set.
Cut off energy is optimized for the unit cell of Na+-MMT by using different cut off
energy values. Experimental and theoretical cell parameters are compared by using cell
shape and volume optimization and root mean square (RMS) coordinate difference is
calculated for variation of cell parameters. Cell shape and volume optimization are done
for calculating optimum expansion or compression constant.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-1263 |
| Date | 15 May 2009 |
| Creators | Atilhan, Selma |
| Contributors | Cagin, Tahir |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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