Photostability and optical parameters of copolymer styrene/MMA as a matrix for the dyes used in fluorescent solar collectors

Copolymer films of styrene (ST) with methylmethacrylate (MMA) of different percentage were prepared. Differential scanning calorimetry shows a single glass transition at 50/50 ST/MMA. Thermogravimetry has been used to compare the thermal stability of the copolymer and homopolymers; the copolymer degradation occurs at higher temperatures than pure PMMA indicating stabilization of that component. FTIR spectroscopy was used to give information on the structural changes consequent upon exposure to UV radiation. The FTIR spectra of copolymer 50/50 ST/MMA after exposure to UV radiation for 24 h is similar to that before exposure, this indicates that the copolymerization of styrene with MMA modifies the photodegradation behavior of polystyrene. There is mutual stabilization for ST/MMA copolymer. The optical absorption (a) and the band gap (E,) have been determined for the films before and after exposure to UV radiation. The optical transmission and reflection data for 50/50 ST/MMA copolymer have been analyzed, and hence the refractive index (n) and extinction coefficient (k) have been determined before and after exposure to UV radiation. (C) 2003 Elsevier Ltd. All rights reserved.