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/cm3, denoted as 8CB+sil. The capacitance of the filled cell, hence the dielectric constant of the sample, was monitored from 24-48C and for the pure 8CB sample found the expected bulk Tni transition at 40C. 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.

• This report represents the work of one or more WPI undergraduate students submitted to the faculty as evidence of completion of a degree requirement. WPI routinely publishes these reports on its website without editorial or peer review.

Creator

• Dewhirst, Brian Albert

Publisher

• Worcester Polytechnic Institute

Identifier

• 02D217M

Advisor

• Iannacchione, Germano S.

Year

• 2002

Date created

• 2002-01-01

Resource type

• Major Qualifying Project

Major

• Physics

Rights statement

• In Copyright