| Abstract: | The decomposition ratio of cation exchange resin (sulfonated ST-DVB copolymer) after pyrolysis is only 50 wt%, while that of ST-DVB copolymer is 90 wt%. Fundamental experiments were performed to investigate the reason for the low decomposition ratio of the former. The cation resin consists of base polymer (ST-DVB copolymer) and functional sulfonic acid groups. Chemical analyses of the pyrolysis products showed that most of the functional groups decomposed at about 300°C and generated SO2 gas. However, only a small amount of the base polymer was pyrolyzed even at 600°C and the total decomposition ratio was only 50 wt%. The XPS studies on the residue showed that 35% of the functional sulfonic acid groups was converted to sulfonyl and sulfur bridges between the base polymers during pyrolysis. These bridges made the base polymers, namely ST-DVB copolymer, thermally stable. |
