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

The results demonstrated that ageing mechanisms were different for anion-exchange membranes and cation-exchange membranes; however, ageing was similar among homogeneous and heterogeneous membranes of the same type (anionic or cationic). Sodium hypochlorite provoked a degradation of the quaternary ammonium sites of anion-exchange membranes and chain scission of the poly(styrene-co-divinylbenzene) backbone from anion and cation-exchange membranes through chain radical oxidation. No significant degradation was found for the polymer binder of membranes investigated in this paper.