Thermosetting Resins Used in FRP Pipe
The following article is taken from Dow Chemical publication about FRP pipe. The materials and processes discussed are similar to the ones used in fabrication of FRP booms. The article gives an independent third party assessment of the three most common resin materials and three most common processing options used for making FRP booms.
Waco Boom uses high-performance epoxy resin and the most modern filament winding production methods. Two other manufacturers are still using polyester resin and the Hand Lay- Up method to make their own booms. One manufacturer is still using vinyl ester resin with the Centrifugal Casting method to make many of its booms.
The only way to know that you are getting an epoxy filament wound boom is to ask for a Waco Boom by name.
Epoxy resins offer a combination of toughness and temperature resistance that makes them ideally suited for high performance fiber reinforced plastic pipe. Dow produces three liquid epoxy resins suited for FRP pipe applications: D.E.R. 383, D.E.R. 331 and D.E.R. 330. The choice of epoxy resin and curing agent combination depends on the fabrication method and the performance requirements of the pipe. This is the method used by Waco Boom Company Ltd.
FRP pipes made with DERAKANE vinyl ester resins from Dow exhibit exceptional chemical resistance in oxidizing agents and high acid-concentration environments. DERAKANE 411-45 is the most widely used resin and provides excellent service in most applications. DERAKANE 470-36 is recommended for additional chemical and temperature resistance. Brominated vinyl ester resins such as DERAKANE 510A-40 are used for fire retardant pipe.
Polyesters are less expensive than other resins used in FRP pipe, but offer only moderate strength and chemical resistance. Polyester pipe is often an economical choice for less demanding, low-pressure service.
Several different types of curing agents or catalysts can be used to chemically harden thermosetting resins. The curing agent affects not only the speed of the chemical reaction, but in the case of epoxies, also the physical properties of the finished pipe. There are two basic classes of epoxy curing agents used in the manufacture of FRP pipe: anhydrides and amines. In general, anhydride-cured resins exhibit good chemical resistance, but modest temperature resistance.
Amine-cured resins generally have good thermal properties as well as excellent chemical resistance. For vinyl ester and polyester resins, peroxides are used as the catalysts.