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Vinyl Ester Resins are NOT Cure-All in Corrosion Service
There has been a tremendous marketing program in the past several years hailing the attributes of vinyl ester resins. The campaign to spread the word has been so successful that some people believe vinyl esters should be used in every FRP application.
Although vinyl ester resins have increased the range of FRP in corrosion applications, they are not the total package that some vision them to be. When considering both corrosion resistance and pricing, there are times when vinyl esters are not the best choice and should not be used.
In the corrosion field of FRP fabrication, we have several types of resins with which we can build composites. Some of these are Isophthalic Polyester, Bisphenol A Fumarate Polyester, Chlorendic Polyester, Vinyl Ester and a few other specialized resins. Each of these resin types has various grades that include a "premium" and a flame retardant/low smoke grade. There are also several companies that produce these resins. The two prominent companies that produce a wide range of quality resins are Ashland Chemical and Reichhold Chemical, while Dow Chemical produces only the vinyl esters. Ashland's resins are marketed under the Hetron and Aropol names while Reichhold's are Atlac and Dion and Dow markets the Derakane label.
The correct resin selection depends on the specific chemical environment, the chemical concentration and the maximum operating temperature. With this information the correct resin system can be selected, without over-designing the needs of the job. An example of this is in many wastewater treatment applications an Isophthalic Polyester resin would be the correct choice for the job at one third the cost of vinyl ester. Also in many other industries (i.e. pulp & paper processing and the plating industry) a "better" resin choice might be a Bisphenol A Fumarate, which, in many applications, would provide service at higher operating temperatures.
Each resin has been designed for a particular application (mild, normal or severe corrosion service along with flame spread). These resins are also priced accordingly. The selection of the best resin system for any one particular application should be based on the need (chemical environment, chemical concentration and operating temperature), not on any resin company's marketing program. The correct resin system, with the proper care, will provide long and care-free service at a fair cost to the customer.
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