CONDUCTIVITY OF LONG-CHAIN SILVER CARBOXYLATES AND THEIR THERMAL-DECOMPOSITION PRODUCTS

We have measured ac conductivities and dielectric properties for silve r stearate and for a silver soap mixture, which is predominantly silve r behenate [AgO2C22H43](2). Excess fatty acid affects conductivity, th ermal expansion and dielectric parameters of these samples. Conductivi ty increases accompanied by conductivity maxima occur at temperatures close to the acid melting points (around 65 degrees C) for samples con taining excess fatty acid. At temperatures higher than 65 degrees C, r elatively high conductivity of these samples is almost entirely the re sult of the acid liquid phase. Conductivity of all the samples under s tudy was independent of Cu2+ content and seems limited by the extent o f excess fatty acid removal. Silver stearate samples free from excess fatty acid show phase transitions at 124 degrees C and at 153 degrees C, The former is irreversible and leads to decreased conductivity, the latter is accompanied by the thermal decomposition of the silver carb oxylates and an increase in conductivity. The conductivity increase an d maximum at 65 degrees C, which appear after decomposition of acid-fr ee silver carboxylate, suggest that free fatty acid is one of the deco mposition product:;. IR spectroscopy confirms that the free fatty acid is indeed the product of this reaction. This acid formation greatly a lters conductivity, and the resulting protons may function as charge c arriers.