Measurement of Optical and Radiation Transmittance of Thermotropic Material

Abstract

Thermally induced switching temperature, spectral transmittance of a new kind of thermotropic material developed by a different mixing proportion of hydroxypropyl methyl cellulose (HPMC), Sodium Chloride (NaCl) and pure water was measured. The optimum mixing proportion of samples for application was determined by solar radiation and outdoor temperature measurements. Radiation transmittance was tested on samples of a thermotropic double glazing window, double glazing window and Low-E double glazing window. Results show that thermotropic double-glazed window with the optimum mixing proportion of HPMC, NaCl and pure water of 2:10:100 by mass reduces radiation transmittance at fully turbid state by up to 72% and 32%, respectively, compared to the ordinary double-glazed window and Low-E double-glazed window which do not have adjustable radiation transmittance, and its radiation transmittance changed from transparent state to light scattering state is up to 60%, indicating a high performance on switching solar radiation and a great potential for energy efficient windows.