Influence of Irradiation Temperature on Grafting of Styrene into Poly(tetrafluoroethylene‐co‐hexafluoropropylene) Films

Abstract

This study concerns with the investigation of the effect of irradiation conditions on grafting of styrene into FEP films by the pre‐irradiation method. EPR spectroscopy was used to characterize the base polymer material regarding the trapped radical species and their concentration. Radiation‐induced changes in the chemical structure were studied by IR spectroscopy. Tensile strength and elongation at break as well as yield of grafting were found to be strongly influenced by irradiation temperature. Main‐chain scissions were identified to be the reason for the deterioration of the mechanical properties after radiation treatment at temperatures below glass transition temperature.magnified image

Grafting of styrene into pre-irradiated fluoropolymer films: Influence of base material and irradiation temperature

“…The tensile strengths and elongations at break achieved at irradiation temperatures of 175 and 225 1C nearly coincide with the values of the non-irradiated PFA within the experimental uncertainty. Similar results were observed for the FEP studied previously (Lappan et al, 2009). It was concluded that the glass transition temperature plays an important role for the radiationinduced processes resulting in the drop of the mechanical properties.…”

“…Previous investigations have shown that for the perfluorinated polymer FEP the irradiation temperature is an important factor for the mechanical properties of the pre-irradiated films (Lappan et al, 2009). Therefore, the temperature of the films during the electron beam irradiation was varied in the present study too.…”

“…All irradiation experiments were carried out under reduced pressure ( o10 À 2 Pa) to eliminate oxygen during the irradiation process as far as possible, because oxygen is known to take part in the radiation-induced reactions. Previous experiments have shown that the irradiation of FEP at room temperature in air at atmospheric pressure results in higher concentration of carbonyl groups than the irradiation at reduced pressure, whereas under both conditions a deterioration of the mechanical properties with increasing dose was observed (Lappan et al, 2009). Pre-irradiation using an electron beam with high dose rate was used in the study, because it is known that gamma irradiation with low dose rate results in enhanced radiation damage of fluorinated materials (Gubler et al, 2005b).…”

“…This advantage has made it to a favorable substrate for radiation grafting (Gubler et al, 2005a;Chen et al, 2006a). Recently, the irradiation temperature was found to be an important factor for tensile strength and elongation at break of pre-irradiated poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) films and for the yield of grafting into the films (Lappan et al, 2009). …”

Small-scale mechanical characterization of space-exposed fluorinated ethylene propylene recovered from the Hubble Space Telescope

“…if not countered by cross-linking [10] . Cross-linking, more prevalent at higher temperatures, is thought to increase both the stiffness and the strength of the Al-FEP [11] .…”