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Photo and Thermal degradation of Plasticized para- Substituted polystyrene in solid films

Khalid E. Al Ani

  

 In recent years, much attention has been focused on re­search to prepare new generation of Poly (para – substi­tuted styrene), and to study the irradiation, thermal and plasticization effects on stability of these new polymers. The effect of irradiation of plasticized Para- substituted polystyrene in solid films was studied at different inter­vals of irradiation times and at different percentages of added phthalates and terephthalates plasticizers. The deg­radation process was followed by UV-VIS, Fluorescence and FT-IR Spectroscopic techniques. to determine the type and amount of degradation that occurs during ir­radiation. The irradiated pure and plasticized polymers solid films showed an increase in the intensity of absorp­tion band by the increase in irradiation time and increase in the amount of added plasticizers. On the other hand the intensity of fluorescence was decrease upon the in­crease in irradiation time and increase in the amount of blended phthalate and terephthalate plasticizers. The analysis of the FT-IR spectra of the irradiated and non-ir­radiated samples, showed a noticeable formation of new bands, and their 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, providing evidence for the photodegradation as well as photo-oxida­tion of polymeric chains. Some kinetics work was applied to the results on fluorescence intensity of the excimeric emission to evaluate the quenching efficiencies and pho­to quenching rate constant by applying Al Ani – Hawi equation. Electrophilic subsitution suchas (Cl, and Br) in the para position of the polymer backbone should less stability towards UV – Irradiation, whereas, necluophilic subsituion such as ( - H, -CH3, -OCH3, -OC2H5, -C6H5, α– CH3, α–OCH3, Phenyl and – C (CH3)4 should higer stability towards irradiation of plasticization.