STRUCTURAL MODIFICATIONS OF VINYLIDENE FLUORIDE-TRIFLUOROETHYLENE(70-30) COPOLYMER INDUCED BY X-RAY-IRRADIATION

X-ray radiation-induced structural changes in the semicrystalline rand om copolymer poly(vinylidene fluoride-co-trifluoroethylene) (70-30) fi lm were studied by Xray diffraction, differential scanning calorimetry , thermogravimetric analysis, ultraviolet/visible and infrared absorpt ion spectroscopies and Raman scattering. The X-ray diffraction shows a decreasing degree of crystallinity with increasing X-ray irradiation times. The differential scanning calorimetry experiments show that the ferroelectric transition temperature T-c and the melting temperature T-m are lowered under X-ray irradiation. Thermogravimetric analysis sh ows one step weight loss with a decreasing decomposition temperature a nd increasing amount of residue with increasing irradiation times. The UV/vis spectra of irradiated copolymer film show the appearance of ab sorptions at similar to 192, 222, 272, 342 and 364 nm related to > C = C <, diene, triene and chromophores of radical ion species, respectiv ely. Infrared spectra show a small high wavenumber shift for bands ass ociated to C-H stretching vibrations, decreasing intensities at 1293 a nd 852cm(-1) and the appearance of new bands at 1847, 1750 and 1717cm( -1), that increase in intensity with irradiation times. Raman spectra show an increasing fluorescence contribution with increase of irradiat ion time. A decreasing intensity of bands at 847 and 884 cm(-1) could be related to decreasing degree of crystallinity of the copolymer film . The X-ray irradiated P(VDF-TrFE) (70-30) films show physical and che mical change consisting in diminished degree of crystallinity, loss of ferroelectric property and the formation of new chemical structures ( >C=C<, diene, triene and chromophores of radical ion species). (C) 199 8 Elsevier Science Limited. All rights reserved.