Thymol-blue dyed poly(vinyl butyral) films for monitoring ultraviolet radiation

Dyed poly(vinyl butyral) (PVB) films prepared by a simple technique of cast ing alcoholic solution of PVB incorporating thymol blue (TB) indicator and chloral hydrate [CCl3CH(OH)(2), 2,2,2-trichloroethane-1,1-diol] on a horizo ntal glass plate are useful for ultraviolet radiation monitoring. These pla stic films undergo colour change from yellow to red upon exposure to UV irr adiation. The radiation-induced change in colour was analysed spectrophotom etrically at the maximum of the visible absorption band peaking at 551 nm. These films have a pronounced response to the main UV radiation spectral re gions [UVA (400-320 nm), UVB (320-280 nm) and WC (280-180 nm)] showing a ma ximum sensitivity at 200 nm. The measurement uncertainty of estimating ultr aviolet radiation energy incident per unit area on the films is found to be 6.6% at a confidence limit of 95% (2 sigma). The study of the effect of ra diance exposure, irradiation wavelength, chloral hydrate concentration and the post-irradiation stability in different storage conditions has been car ried out to characterise the use of these films for actinometric monitoring ultraviolet radiation. (C) 2000 Elsevier Science B.V. All rights reserved.