Abstract
Polyvinyl alcohol films were dyed by some direct dyes, and colored cellulose diacetate films were prepared by means of mixing the above dyes with the cellulose diacetae-aceton solution before the formation of the film.
Changes in absorption spectra of these films by dry heating were studied and the following results were obtained:
a) The spectral change is observed by dry heating of PVA film dyed with Benzo Azurine G, but such color change is not observed in cellulose diacetate film colored with the same dye.
b) The deformation of the absorption curves is generally observed by after-treatment with the CuSO4 aqueous solution. By this treatment Benzo Azurine G in PVA film reduced the color change by dry heating.
c) Copper complex direct dyes in films did not show any appreciable shift of maximum wavelength by dry heating, that is, there is no color change.
