Changes in Properties and Structure of Polyethylene Terephthalate Film Under Vacuum Ultraviolet

摘要

The effect of vacuum ultraviolet (VUV) radiation on polyethylene terephthalate (PET) film was investigated on a gas-jet VUV source with a wavelength of 5-200 nm. The experimental results show that under VUV irradiation both tensile fracture strength and elongation decrease slightly. The spectral absorbance of the PET film increases noticeably with increasing dose. An absorption band mainly forms in the ultraviolet-to-visible region. X-ray photoelectron spectroscopy, Fourier transform infrared, and electron spin resonance analyses indicate that in the skin layer of PET film under VUV radiation, the C-O bonds are broken and decarbonylation occurs, leading to the formation of free radicals as well as a trend to carbonification. The scission of the macromolecule chains, the increase in radical concentration, and the carbonification are considered to be major contributors to the change of optical properties for PET film under VUV exposure.