Cation exchange membranes by radiation-induced graft copolymerization of styrene onto PFA copolymer films. I. Preparation and characterization of thegraft copolymer
Mm. Nasef et al., Cation exchange membranes by radiation-induced graft copolymerization of styrene onto PFA copolymer films. I. Preparation and characterization of thegraft copolymer, J APPL POLY, 73(11), 1999, pp. 2095-2102
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 solv
ents, i.e., methanol, benzene, and dichloromethane, were used as diluents i
n 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 h
ighest value at a styrene concentration of 60 (vol %). The dependence of th
e 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 inc
rease in irradiation dose, while it considerably decreased with the increas
e in dose rate. The formation of graft copolymers was confirmed by FTIR ana
lysis. The structural investigation by X-ray diffraction (XRD) shows that t
he degree of crystallinity content of such graft copolymers decreases with
the increase in grafting, and consequently, the mechanical properties of th
e graft copolymers were influenced to some extent. Both tensile strength an
d elongation percent decreased with the increase in the degree of grafting.
(C) 1999 John Wiley & Sons, Inc.