Why is fiberglass not resistant to caustic soda?
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Many sources state that fiberglass is a material resistant to acids and alkalis; in reality, however, it is not resistant to caustic soda. Could everyone discuss the reasons why fiberglass is not resistant to alkalis? Why does most information consider fiberglass-reinforced plastic to be an alkali-resistant material?
FRP is resistant to caustic soda, but only under certain concentrations and temperatures.
Different types of fiberglass have varying corrosion resistance. The fiberglass material we often refer to is epoxy resin, which can withstand low concentrations of acids and caustic soda; whereas polyester resin-based fiberglass cannot resist caustic soda!
Generally speaking, it is meaningless to discuss whether fiberglass-reinforced plastic is resistant to alkalis; it is the choice of resin that determines its corrosion resistance. Vinyl resin does provide resistance to alkaline solutions, but of course this resistance is subject to limitations regarding concentration and temperature!
Like all composite materials, fiberglass-reinforced plastic is composed of two types of materials. One part is known as reinforcing material, which serves as the framework in composite materials ； The other part is called the matrix material, which serves to bind the components together in a composite material. The reinforcing material in fiberglass is glass fiber. Glass fiber is an inorganic fiber material made by drawing or blowing molten glass, and its main chemical components include silica, alumina, boron oxide, magnesium oxide, sodium oxide, etc. The fibers produced include filaments, short fibers, and flocculent materials, with a diameter generally ranging from 3 to 80 micrometers; even the thickest ones are only as thick as human hair. Glass fibers with a diameter of 10 micrometers have a tensile strength of 3600 megapascals, which means they can withstand a pulling force of 360 kilograms per square millimeter without breaking. This strength is twice higher than that of high-strength steel. In terms of composition, since its reinforcing materials are mainly glass fibers, such as silica and alumina, it is easy for them to react under strongly alkaline conditions, that is, when in contact with caustic soda.
What was said on the 6th floor makes some sense. However, for fiberglass materials, it is required that no fibers be exposed on the inner surface; therefore, if the manufacturing process is proper, the fibers should not come into contact with alkaline substances. Moreover, for inner surfaces that require alkali resistance, glass fibers are not used instead polyester surface felt is employed
There are many types of fiberglass reinforced plastic, and its resistance to alkalis depends mainly on the properties of the resin. If it is epoxy resin, it generally cannot be used in strong alkalis (such as caustic soda), especially at higher temperatures, as corrosion will be severe. If it is an amine-cured resin, its alkali resistance is much better.
There are many types of fiberglass-reinforced plastics; phenolic types can only resist acids, not bases, while epoxy or furan-based types can resist bases, but they still have issues with strong bases or high temperatures.
The theme on the 1st floor is a false proposition!
The views from the sixth and seventh floors are generally in agreement.
Glass fiber reinforced plastic cannot be used to hold liquid alkali; at the very least, it must be acid-resistant glass fiber reinforced plastic