Images Intensity Analysis of Thermochromic Liquid Crystal near Critical Temperature

Abstract

In this paper, the thermal-optical analysis based on images intensity distribution of thermochromic liquid crystals sample near critical temperature under crossed polarizer microscope is discussed. Thermochomic liquid crystals (TLCs) is composed from chiral nematic liquid crystals which have twisted molecular structure and optically active. TLCs show the blue-red colorplay at critical temperatures which color changes occured. According to experimental result, crossed-twist pattern appears when the temperature approaches a higher critical temperature of sample at 32 °C . The different of the molecules orientation cause uneven of intensity distribution along the twist-line. According to measurement, the length of a twist-line is equivalent to half of the pitch (p/2), which mean that the molecules twist at 180°, and also equivalent to half of sample thickness (h/2). Moreover, the consistency of twist-line length measurement at various temperatures shows the stability of twist-line near higher critical temperature.