RADIATION-SENSITIVE INDICATOR BASED ON RADIATION-CHEMICAL FORMATION OF ACIDS IN POLYVINYL BUTYRAL FILMS CONTAINING CHLORAL HYDRATE

Radiation-sensitive indicators based on dyed polyvinyl butyral (PVB) c ontaining acid-sensitive dye (bromophenol blue, BPB) and chloral hydra te (CCl3CH(OH)(2), 2;2,2-trichloroethane-1, I-diol) have been develope d. These plastic film dosimeters undergo colour change from blue (the alkaline form of BPB) to yellow (the acidic form of BPB), indicating a cid formation. The concentration of radiation-formed acids in the film s containing different concentrations of chloral hydrate was calculate d at different doses. The kinetics of the acid-formation reaction is d iscussed, indicating a half-order reaction with respect to chloral hyd rate concentration. These films can be used as dosimeters for food irr adiation applications where the maxima of the useful dose ranges are b etween 1 and 4 kGy depending oh chloral hydrate concentration in the f ilm. The response of these films depends on temperature during irradia tion; therefore a correction should be applied. These films have the a dvantage of negligible humidity effects on response in the intermediat e range of relative humidity from 10 to 70% as well as good post-irrad iation stability when stored in the dark at room temperature. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.