TITLE:
Kinetic Study of the Effect of Plasticization on Photodegradation of Polystyrene Solid Films
AUTHORS:
Khalid E. Al Ani, Afrah Essa Ramadhan
KEYWORDS:
Excimer Fluorescence, Photodegradation Kinetics, Phthalateplasticizers, Polystyrene
JOURNAL NAME:
Materials Sciences and Applications,
Vol.6 No.7,
July
8,
2015
ABSTRACT: The effects of UV-irradiation on stability of pure and blended polystyrene films with phthalate and
terephthalate plasticizers were studied in presence of air. UV-visible, fluorescence and FT-IR techniques
were used to study the photodegradation of irradiated polystyrene films. Increase of irradiation
times of polystyrene films caused an increase in the intensity of the main absorption
band and the increase in the intensity of a new absorption band at longer wavelength, thus indicating
a possibility of photo degradation of polystyrene chains. The influence of added plasticizers,
dimethyl terephthalate, diethyl terephthalate, dioctyl terephthalate, dioctylphthalate, and dibutyl
phthalate on photo-quenching of the polymer fluorescence band was also investigated, and found
to increase the photodegradation processes in polymeric chains. On the other hand, the intensity
of excimer and monomer fluorescence bands maxima was also found to decrease with a small red
shift with the increase in irradiation times. These changes may be attributed to the formation of
new photo-products resulted from the photodegradation of irradiated polymeric chains. The photo-
quenching rate constant was found to increase with the increase of the molar mass and bulkiness
of the used plasticizers and to increase with the increase in irradiation time. The rate constant
of the photo quenching process was found to decrease with the increase in the percent of
added plasticizers, indicating that the added plasticizers might act as UV-absorbers which inhibited
the photodegradation process. The analysis of the FT-IR spectra of the irradiated and nonirradiated
samples showed a noticeable formation of new broad band centered at 1727 cm-1, and
its intensity was found to increase with the increase in irradiation time and also with the increase
in the amount of added plasticizer. In addition, the observed increase in the intensities of the carbonyl
and hydroxyl absorption regions of the FT-IR spectra provided evidence for the photodegradation
as well as photo-oxidation of polymeric chains.