Preirradiation grafting of N‐vinyl‐2‐pyrrolidone onto poly(tetrafluoroethylene) and poly(tetrafluoroethylene‐hexafluoropropylene) films

Abstract

Preirradiation grafting of N‐vinylpyrrolidone (NVP) onto poly(tetrafluoroethylene) (PTFE) and poly(tetrafluoroethylene‐hexafluoropropylene) (FEP) films was investigated. The influence of grafting parameters such as preirradiation dose, monomer concentration, and grafting temperature on the rate and grafting yield was studied. Different solvents were used for diluting the monomer and it was found that the aqueous monomer solution at a concentration of 80 wt% was suitable for this grafting system. However, the graft polymerization of NVP in benzene terminated within a short time without significant grafting yield. The dependence of the grafting rate on preirradiation dose and monomer concentration was 1.2 and 1.07 order, respectively, for grafting onto PTFE films and 1.1 and 1.2 order, respectively, for grafting onto FEP films. Arrhenius plots for grafting onto PTFE films showed a breaking point at ca. 35°C and the overall activation energies were calculated as 23.6 and 9.0 Kcal/mol below and above 35°C, respectively. For grafting onto FEP films, however, no break was observed in the Arrhenius plots; the overall activation energy was 11.9 Kcal/mol. The swelling behavior and electric resistance of the grafted materials were investigated.

Adsorption of CO2+ by stylene-g-polyethylene membrane bearing sulfonic acid groups modified by radiation-induced graft copolymerization

“…The inclusion of divinylbenzene and H 2 SO 4 increases the grafting yields for all solutions studied. The level of enhancement by divinylbenzene is generally not as significant as found with H 2 SO 4 . The enhancement of grafting yield by multifunctional monomer seems to accelerate grafting by chain branching.…”

“…The effect of H 2 SO 4 concentration on the grafting yield is shown in Figure 2. As shown in Figure 2, the grafting yield increased rapidly with increased H 2 SO 4 .…”

“…The degree of grafting increased with increased reaction time at 50°C. On the other hand, the grafting reaction proceeded very slightly at 30°C, regardless of the inclusion of H 2 SO 4 . Figure 5 shows the relationship between pore diameter distribution and the grafting yield when PEHM was grafted with styrene.…”

“…The enhancement of grafting yield by multifunctional monomer seems to accelerate grafting by chain branching. Figure 4 shows the effects of reaction time on the grafting of styrene onto 40 kGy-irradiated PEHM at a temperature of 30°C and 50°C in the presence and absence of H 2 SO 4 . The degree of grafting increased with increased reaction time at 50°C.…”

Proton exchange membranes prepared by simultaneous radiation grafting of styrene onto poly(tetrafluoroethylene-co-hexafluoropropylene) films. I. Effect of grafting conditions

“…4,5 Of the fluorinated polymers, poly(tetrafluoroethylene-co-hexafluoropropylene (FEP) is advantageous in terms of high radiation resistance, which provides the possibility for applying a wide range of irradiation doses. 6,7 A number of studies were published on grafting of weak acids such acrylic acid onto FEP films. 8 -12 Two groups studied the preparation of a proton exchange membrane by preirradiation grafting of styrene onto FEP followed by a sulfonation reaction.…”