2001 Volume 69 Issue 2 Pages 98-103
Composite membranes of zeolites and hydrated styrene butadiene rubber (HSBR) were investigated with a view to developing a new flexible electrolyte. The evaluated zeolites were multivalent-cation exchanged Y-type zeolites and various types of proton-substituted zeolites. The membranes were fabricated by casting method. The solid acidity of the zeolites was analyzed with the results of the ammonia TPD measurement. Two acid sites were observed in the measurement, that is, strongly and weakly adsorbed ammonia molecules were detected. In the multivalent-cation exchanged Y-type zeolite membranes, the conductivity increased with increasing the weak acid sites. The proton-substituted zeolite membranes were examined by the pyridine-IR method carried out in a reduced pressure. The membranes showed high conductivity when the Bronsted acid sites increased. A Ca2+-exchanged Y-type zeolite exhibited the highest ion conductivity of 6 × 10−5 S/cm. The measurement was made with a membrane containing 80 wt% of zeolite particles, at room temperature in the relative humidity of 100%.