Abstract
The typical forms of degradations in various dye + LC mixtures under increased UV radiation are discussed. The forms of degradation are illustrated by microphotographs. The proposed stability factor (SF) permits a quick quantitative comparison for UV stability. The usefulness of SF is demonstrated with several commercially available dyes and with Di-Triazolo-Benzoate (DTB) derivatives. These DTB derivatives synthesized for our purposes exhibit positive absorption anisotropy, liquid crystalline like behavior above 120°C and high UV stability. By introducing the concept of Stabilizing Influence of Dyes (SID) the interpretation of some interesting effects observed in connection with the UV stability of various mixtures is given.