Structure and properties of heterogeneous and homogeneous ion-exchange membranes subjected to ageing in sodium hypochlorite

摘要: Abstract The effects of sodium hypochlorite (NaClO) on ion-exchange membranes were carefully investigated and discussed with the aim to assess one their possible causes ageing. A thorough comparison was carried out for degradation different structures, i.e. homogeneous heterogeneous ones, as well functional groups, anionic (bearing 3CH2N+R3 groups) cationic − SO 3 ones. An artificial ageing protocol implemented, which consisted in immersing four types membranes, AMX-SB CMX-SB heterogeneous, MA-41 MK-40 aqueous NaClO solutions at constant pH concentration times over a 700 h period. physico-chemical, structural, mechanical properties each sample investigated, before after ageing, by means complementary analytical techniques, namely conductivity, capacity, water uptake, thickness measurements, SEM, ATR-FTIR, TGA, tensile strength tests. results demonstrated that mechanisms anion-exchange cation-exchange membranes; however, similar among same type (anionic or cationic). Sodium provoked quaternary ammonium sites chain scission poly(styrene-co-divinylbenzene) backbone from anion through radical oxidation. No significant found polymer binder this paper.