Cation exchange membranes by radiation‐induced graft copolymerization of styrene onto PFA copolymer films. I. Preparation and characterization of the graft copolymer

Abstract

PFA-g-polystyrene graft copolymers were prepared by simultaneous radiation-induced graft copolymerization of styrene onto poly(tetrafluoroethylene-co-perfluorovinyl ether) (PFA) films. The effects of grafting conditions such as monomer concentration, dose, and dose rate were investigated. Three solvents, i.e., methanol, benzene, and dichloromethane, were used as diluents in this grafting system. Of the three solvents employed, dichloromethane was found to greatly enhance the grafting process, and the degree of grafting increased with the increase of monomer concentration until it reached its highest value at a styrene concentration of 60 (vol %). The dependence of the initial rate of grafting on the monomer concentration was found to be of the order of 1.2. The degree of grafting was found to increase with the increase in irradiation dose, while it considerably decreased with the increase in dose rate. The formation of graft copolymers was confirmed by FTIR analysis. The structural investigation by X-ray diffraction (XRD) shows that the degree of crystallinity content of such graft copolymers decreases with the increase in grafting, and consequently, the mechanical properties of the graft copolymers were influenced to some extent. Both tensile strength and elongation percent decreased with the increase in the degree of grafting.

PVDF and P(VDF-HFP)-based proton exchange membranes

“…In particular, they prepared fluorinated sulfonated films by means of g or electron beam radiation, focusing their attention on the synthesis conditions, the in situ electrochemical performances and mostly on the structural aspects of the derived systems. PVDF [13] and some HFP-based copolymers [16], FEP [17], PTFE and PFA [18] have been the starting matrices of greater interest. However, little attention has been devoted to address the relationships among the membrane morphology/microstructure and its hydrophilic and electrical properties.…”

Radiation‐grafted ion‐exchange membranes: Influence of the initial matrix on the synthesis and structure

“…The advantages of this approach include a high degree of control over the synthesis, low production costs, and the existence of a preprocessed film. Polytetrafluoroethylene (PTFE),6 polytetrafluoroethylene‐ co ‐hexafluoropropylene (FEP),5 polyethylene‐ alt ‐tetrafluoroethylene (ETFE),5 polyvinylidene fluoride (PVDF),4 and polytetrafluoroethylene‐ co ‐perfluorovinylether (PFA)7 have all been used as host matrices for the PSSA grafts, but comparing the membranes obtained is problematic because each group has its own preferred initial fluoropolymer and different grafting and sulfonation procedures. Differences in the grafting conditions lead to different PS distributions, and in some cases to different mechanical properties 8.…”

Preparation of chelating fabrics by radiation‐induced grafting of itaconic acid and acrylonitrile onto polypropylene nonwoven fabrics and subsequent amination of graft copolymer

“…The relationship between the grafting yield and methanol content in DMF‐methanol mixture is shown in Figure 4. It is well known that a polymer swollen in a solvent represents a medium of high viscosity and that it is the viscosity of the grafted layers controls the diffusion of the monomer to the grafting sites 10–12. The swelling of PP fabrics in methanol and DMF was found to be 0.25 and 0.15 wt %, respectively.…”