(in English) |
Fluoro-benzoic acids (2-, 3-, 4-FBA), difluoro-benzoic acids (2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5-F2BA) and trifluoro-benzoic acid (2,3,4-, 3,4,5-F3BA) were mixed with the Hydrogen-Bonded Liquid Crystal of alkylbenzoic acids. Physical properties of dielectric constants, elastic constants and refractive index anisotropy were measured. The effect of the fluorine position in the phenyl ring on the physical properties was investigated. Dielectric anisotropy decreased by adding 2-FBA and 2,3-F2BA and increased by adding 4-FBA, 3,4-F2BA, 3,5-F2BA, 2,3,4-F3BA and 3,4,5-F3BA. With the addition of 3,4,5-F3BA, the dielectric anisotropy increased with increasing mixing concentration up to about 40 wt%, and them decreased. K11 and K33 of all mixed liquid crystals decreased. Threshold voltages decreased from matrix liquid crystal except for 2,3-F2BA, which was reduced by about one-fifth by mixing 55 wt% of 3,4,5-F3BA. |