XRD, Raman and photoluminescence study of gamma-irradiated PBT

This paper is devoted to study the gamma radiation effect on polybutylene terephthalate properties, with doses up to 500 kGy, highlighted by the X-ray diffraction (XRD) technique, the Raman and photoluminescence (PL) spectroscopies. The crystallinity reduction and the development of microstrain in the crystallites after radiation were observed by XRD. The microstrain generated during chain scission and crosslinking mechanism affect crystalline form (α to β) after irradiation. The Raman spectroscopy served to study the microstrain and the amorphization; the obtained results confirm those obtained by XRD technique. It is found from PL spectra that the luminescence of PBT is strongly modified after irradiation. In fact, the PL spectra show, in addition to the luminescence spectrum of the pristine PBT, a shoulder whose intensity increases and position red shifts, with the gamma rays dose. At 500 kGy, the shoulder was developed into a new luminescence band centered at about 545 nm.