Fatigue Determination of Photo chromic Dyes in Silica and Polyamide Matrices via Analysis of CIELAB Parameters

To address reported problems in investigating photochromic dye fatigue, this paper describes a new method of “dissolved” photochromic organic dye analysis within polar silica matrices. Conditions under which a photochromic response occurs in a given material are defined by specifying the light source (irradiation wavelength) and exposure time that leads to photochromism. Fatigue, defined as poor lightfastness, is researched through consecutive cycles of exposure to the direct influence of a defined UV irradiation source. From the spectrophotometric graphic analysis in CIELAB, a conclusion can be made on the lifespan of photochromic textile products. This paper addresses issues regarding the rate of color development, and the controlled, predictable return to a colorless state, which is the base of any device working on the principle of reversibility.