Photodegradation of polystyrene containing flame-retardants: wavelength sensitivity and efficiency of degradation

Wavelength dependence on the photodegradation of flame-retardant materials (Polystyrene (PSt) containing flame-retardants) was studied. The effects of nine flame-retardants containing bromine (Br) on the efficiency of photodegradation of the PSt were compared. Samples were irradiated at 23 °C in air with monochromatic radiation of wavelengths 260, 280, 300, 320, 340, 360 and 380 nm using the Okazaki Large Spectrograph (OLS). UV-visible and FTIR spectra were measured to identify photo-induced chemical structural changes in the PSt. The number of main-chain scissions and the changes in the molecular weight distribution were estimated from the results of GPC measurements. It was found that the photo-stability of PSt was reduced by the addition of flame-retardants. The most effective irradiation wavelength for main-chain scission was found to be 280 nm for each flame-retardant except one. The photo-stability of PSt containing flame-retardants appears to depend upon the chemical structure of the additive.