B. Gupta et al., CROSS-LINKED ION-EXCHANGE MEMBRANES BY RADIATION GRAFTING OF STYRENE DIVINYLBENZENE INTO FEP FILMS/, Journal of membrane science, 118(2), 1996, pp. 231-238
Ion exchange membranes were prepared by simultaneous radiation graftin
g of styrene into FEP films and subsequent sulfonation, Divinylbenzene
was used as crosslinker in the grafting medium. The distribution of p
olystyrene grafts across the membrane matrix was determined by micropr
obe measurements. It was observed that for low levels of grafting such
as 13%, crosslinked membranes had a better homogeneity in graft distr
ibution across its matrix as compared to the non-crosslinked ones. The
latter showed a much higher concentration of grafts at the surface th
an in the middle of the film. The membrane characteristics, such as sw
elling and specific resistivity as a function of the degree of graftin
g and crosslinking were evaluated. Membranes showed a sharp decrease i
n the resistivity up to similar to 25% grafting, beyond which the decr
ease was not significant. The higher the crosslinker content, the high
er was the ionic resistivity. A relation between the degree of graftin
g and membrane properties, such as degree of swelling and specific res
istivity as a function of the crosslinker content was established.