Composite materials with field-induced anisotropy
- Sandia National Labs., Albuquerque, NM (United States)
When a colloidal suspension is subjected to a sufficiently large electric field, the induced dipolar particle interactions will cause chaining along field lines. If the continuous phase is polymerizable, e.g., a thermosetting resin, the anisotropic structures produced by the field can be pinned by the sol-gel transition of the resin. The solid materials so produced have marked anisotropies in permittivity and other properties, that are strongly dependent on the particle concentration, pinning time, and field strength. In addition to synthesizing these materials, we have written a Langevin dynamics simulation of structure formation in an applied field, using the simple dipole interaction potential, Stokes friction for the spheres, and a correlated fluctuating force. We have simulated particle `column` formation in a uniaxial electric field and particle `sheet` formation in a rotating field and developed a number of ways of operationally defining anisotropy, including the dipolar interaction energy, dielectric constants and optical attenuation along different axes, and scattering functions. We will describe the concentration dependence of these properties, and will compare these to experimental light scattering and permittivity measurements.
- Research Organization:
- Sandia National Laboratory
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 560419
- Report Number(s):
- CONF-970443--
- Country of Publication:
- United States
- Language:
- English
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