Effect of Alkali Treatment on the Mechanical Properties of Anion-Exchange Membranes with a Poly(vinyl Chloride) Backing and Binder  
[PERSON]  
1 Aatom Corporation, 1-1 Mikagecho, Syuman, Yamaguchi 745-8648, Japan; 12 Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan; 13 International Institute for Carbon-Neutral Energy Research (WPI-I2 CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan; 31 Ikuot@i2 cner.kyushu-u.ac.jp  
[PERSON]  
3 International Institute for Carbon-Neutral Energy Research (WPI-I2 CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan; 31 Ikuot@i2 cner.kyushu-u.ac.jp  
[PERSON]  
2 Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan; 22 Graduate  
In addition, the effect of alkali contact on the mechanical characteristics of AEMs has been discussed [2; 3; 4; 5; 6]. [PERSON] reported that the Mullen burst pressure of custom-developed chloromethylated polysulfone AEMs decreased to less than 1/3 that of the original AEMs after treatment in an alkali solution [2]. [PERSON] et al. systematically studied changes in the mechanical strength of IEMs by alkali treatment [3; 4; 5; 6]. [PERSON] et al. investigated the mechanical properties of AEMs and cation-exchange membranes (CEMs) after 2 years of operation in a commercial food plant. They discovered a 4% and a 63% decrease in the Young's modulus and rupture strength for the AEMs, respectively, compared with the pristine membranes, whereas 6% and 13% for the CEMs [3]. Although both membranes had a woven PVC backing, scanning electron microscopy (SEM) observations showed that they were peeled from the backing with degradation of the sulfonated polystyrene [4]. [PERSON] et al. focused on AEMs and investigated the deterioration of the membranes until the \"lifetime of the membranes\" after desalting whey for several thousand hours on an ED commercial plant. The Young's modulus was down to 80% that of the pristine material, whereas the breaking elongation decreased to 42%. The area below the strain-stress (SS) curve decreased by 24% compared with the original value. The membrane features changed from rigid and tough to rigid and brittle upon alkali treatment [5]. Furthermore, [PERSON] et al. immersed a homogeneous AEM and CEM at room temperature in 2 M NaOH and HCl for up to 700 h. In addition, a cleaning cycle was performed for the AEM and CEM up to 400 times at 40 \({}^{\circ}\)C, as follows: 0.1 M NaOH for 30 min, a water wash, 0.1 M HCl for 30 min, and a water wash. They also investigated the effect of the cleaning cycle on the mechanical performance [6]. However, no studies have systematically investigated the effects of alkali treatment conditions (temperature, concentration, and time) on the mechanical properties of IEMs.  
In this study, we conducted an evaluation focusing on the mechanical properties such as burst pressure and tensile strength, which are particularly useful in the field, and clarified the quantitative change in the mechanical strength of AEMs before and after alkali treatment. Furthermore, we analyzed their chemical structure, considered the mechanism of chemical structure change, and analyzed their contribution to the change in the mechanical strength of AEMs.