Abstract
Polyphosphates have been used as polystyrene photostabilizers against ultraviolet irradiation for long period. The efficiency of polyphosphates was herein evaluated by the use various techniques that include determination of the weight loss, average molecular weight, chain-scission, and degree of deterioration, in addition to infrared spectroscopy of the polystyrene films following irradiation for up to 300 h at room temperature. The results showed that the addition of polyphosphates at low concentrations significantly enhanced the photostability of polystyrene. In addition, the surface morphologies of the polystyrene films were inspected by the use of optical, atomic force, and scanning electron microscopy. The surfaces of the polyphosphate-containing polystyrene films were significantly smoother and contained lower numbers of cracks compared to the blank films. Furthermore, the polyphosphate bearing ortho substituents was the most effective photostabilizer. Scanning electron microscopy of the polystyrene film containing this polyphosphate showed that after 300 h of irradiation, ball-like pores of varying diameters (3.25-4.26 mu m) and shapes (ellipsoid and sphere) were present.