Faculty Advisor

Iannacchione, Germano S.

Abstract

A temperature controlled capacitance cell designed for liquid and semi-liquid samples was constructed in order to characterize the behavior of the dielectric constant of pure and disordered liquid crystal samples through the nematic to isotropic (N-I) phase transition in the presence of an external electric field. The pure liquid crystal sample was octylcyanobiphenyl (8CB) and the disordered liquid crystal sample was 8CB with a dispersed hydrogen-bonded Aerosil gel having a density of 300 g/cm?, denoted as 8CB+sil. The capacitance of the filled cell, hence the dielectric constant of the sample, was monitored from 24-48?C and for the pure 8CB sample found the expected bulk Tni transition at 40?C. For 8CB+sil sample, the applied AC-electric field was cycled from low to progressively larger values and found that an irreversible change in the capacitance cell occurred between 80,000-113,000 V/m. which indicated the disordering strength of this density Aerosil gel.

Publisher

Worcester Polytechnic Institute

Date Accepted

January 2002

Major

Physics

Project Type

Major Qualifying Project

Accessibility

Restricted-WPI community only

Advisor Department

Physics

Advisor Program

Physics

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