UV-Vis, IR and XPS analysis of UV induced changes in PVC composites

PVC undergoes a high degree of dehydrochlorination when exposed to energeti c photons. The released HCl (acid), however, can be trapped if a suitable t rapping material (base) is also enclosed within the solid matrix as a resul t of formation an acid-base adduct. Color changes or electrical conductivit y changes can easily be obtained if suitable acid-base indicators or conduc ting polymers in their basic (nonconducting) form are enclosed in the matri x as trapping materials. We used bromcresol green and polyaniline for induc ing color and electrical conductivity changes, respectively, within the PVC matrix as a result of exposure to UV light at 254 nm. Both changes can to some extent be reversed by further exposure of the films to NH3 vapour. The color and electrical conductivity changes and their reversibility were fol lowed by using W-Vis, IR and XPS spectroscopic techniques. (C) 1999 Elsevie r Science B.V. All rights reserved.