11 - Handling, Storage, and Installation

Abstract

This chapter describes safe handling procedures and precautions that should be followed with perfluorinated sulfonic acids. Fluorinated ionomer products in the precursor form, in general, do not require special precautions in handling and storage. Products in the ionic form (hydrogen, sodium, potassium, etc.) are subject to mechanical damage, particularly when folded or creased. Products in the free sulfonic acid form also tend to pick up contaminants from the environment. Damage by sharp objects obviously must be avoided. Sharp folding will leave a permanent set in a sheet. Products in the free sulfonic acid form will pick up foreign cations on contact with tap water or other ion-containing solutions. In addition, they will pick up contaminants in vapor form, obviously any volatile base, such as ammonia or amines. Organic compounds that can undergo acid-catalyzed condensation reactions can cause discoloration of sulfonic acid products. A razor blade, knife, or scissors may be used for cutting. Because membranes are usually installed wet, a decision must be made whether to cut wet or dry. Installation of a dry membrane in an electrolyzer will result in wrinkling after exposure to the electrolyte. It is the purpose of the pretreatment to obtain an operating membrane that is flat without wrinkles or excessive tension. Install wet membranes promptly after pretreatment to prevent drying. In early applications of NAFION membranes, the use of ordinary rubber gaskets had in some instances caused tearing of the edges on the membranes. The problem was solved by adding a reinforcement or by using a foam gasket.