T/SDMS 014-2025 Requirements for Interlayer Separation Indicators and Test Methods of Perfluorinated Ion Exchange Membranes Used in the Chlor-Alkali Industry

Scope

Scope: This document applies to the design, production, and inspection of perfluorinated ion exchange membranes used in the chlor-alkali industry. Main technical content: This document specifies the concept, principle, and indicator requirements for interlayer separation of perfluorinated ion exchange membranes used in the chlor-alkali industry, and describes the corresponding testing methods and result determination methods. When operating at high current densities (such as 6.0 kA/m2) and with excessively high cathode electrolyte concentrations, the moisture content of the carboxylic acid layer in the perfluorinated ion exchange membrane decreases and becomes lower than that of the sulfonic acid layer. At the same time, the transmission rate of water molecules in the sulfonic acid layer is faster than that in the carboxylic acid layer. At this time, water gradually accumulates at the interface between the sulfonic acid and carboxylic acid layers, eventually leading to interlayer separation between the membrane layers. Based on the speed of interlayer separation in a batch of membranes, the relative resistance of this batch of chlor-alkali ion exchange membranes to interlayer separation can be evaluated. The interlayer separation test results of membranes that have been circulated and used in the market without interlayer separation during their standard lifespan are used as a benchmark to determine whether a batch of products has a satisfactory resistance to interlayer separation.

Development Information

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