B. Gupta et al., PROTON-EXCHANGE MEMBRANES BY RADIATION GRAFTING OF STYRENE ONTO FEP FILMS .3. STRUCTURAL INVESTIGATION, Journal of applied polymer science, 54(4), 1994, pp. 469-476
Structural investigation on proton-exchange membranes, obtained by the
radiation grafting of styrene onto FEP films and subsequent sulfonati
on, was carried out by differential scanning calorimetry. The membrane
crystallinity was found to show a decreasing trend with increasing de
gree of grafting. The melting temperature of all the membranes also sh
owed a slight decrease as compared to the ungrafted FEP. The results h
ave been explained in terms of the cumulative effect of the decrease i
n the crystalline/amorphous ratio by the incorporation of amorphous po
lystrene grafts and of disruption of spherulitic crystallites of the F
EP component in the membranes. The glass transition temperature of the
membranes with different water contents was also evaluated. A correla
tion of the glass transition temperature with the residual water in dr
ied membranes was established. (C) 1994 John Wiley & Sons, Inc.