Journal of Applied Polymer Science, Vol.70, No.8, 1471-1481, 1998
The effect of some fluoropolymers' structures on their response to UV irradiation
The response of three commercial fluoropolymer films, untreated and gamma-irradiated poly(vinyl fluoride) (PVF), poly(vinylidene fluoride) (PVDF), and poly(ethylene-co-tetrafluoroethylene) (ETFE), to ultraviolet (UV) irradiation was studied. The changes in tensile properties, thermal behavior, and chemical structure were investigated. The UV resistance of the PVF film is the lowest, and that of ETFE is the highest among the studied films. The biaxially oriented PVF films undergo massive chain scission under the UV irradiation. The chain scission process in both oriented PVF and PVDF films, although at different levels, is accompanied by increased solubility, increased upper glass transition temperatures, and decreased elevated temperature shrinkage. The UV exposure at 50 degrees C, above the polymers' T-g has annealing effects, mainly reflected by a shift to higher temperatures of their upper glass transition. PVF films are unaffected by a low-dose ionizing radiation. However, the gamma-irradiated films show reduction of their UV resistance. PVDF films undergo both chain scission and crosslinking by gamma radiation, and the addition of UV exposure mainly causes further chain scission.