Fiber-reinforced polymers epoxy vinyl ester

FRP materials are made up of the polymer and reinforcing fibers. The polymer is typically a thermoset polymer thermoplastics can be used as well. Some typical thermoset polymers used are epoxy resins, unsaturated polyester resins, epoxy vinyl ester resins, phenolic resins, and high performance aerospace resins such as cyanate esters, polyimides, and bismaleimides. These resins... 

As discussed above, the nautical field is one of the most important fields in which epoxy resins are used, mainly as matrices for fiber-reinforced polymers but also as adhesives and paints. Unlike aerospace applications, in which epoxy resins have been the norm for years, in the nautical field nowadays more than 90% of pleasure boats under 60 feet are still made with polyester resin, thanks to their lower costs. In fact epoxy resins are more expensive than vinyl ester resins and the latter are about twice as expensive as polyester ones. Since the resin can constitute up to half the weight of a composite component, this price difference has a significant impact on the cost of the laminate. 

Many different thermosetting polymers are used in pultmsion, eg, polyester, vinyl ester, epoxy, and urethane. Reinforcements must be in a continuous form such as rovings, tows, mats, fabrics, and tapes. Glass fibers are the low cost, dominant composition, but aramid and carbon fibers are also used. 

This chapter will deal with the chemistry and applications of epoxies, phenolics, urethanes, and a variety of current vogue high-temperature polymers. Applications in fiber-reinforced plastics will be discussed in the individual sections on resin chemistry where appropriate. Separate sections will deal with adhesives and sealants. Adhesives are most important because, as early history demonstrates, they led the way to the application of resins in aerospace. A section is also included on silicone and polysulfide sealants. Although these materials are elastomers rather than resins, no discussion of aerospace polymers would be complete without some mention. Some major thermosetting polymers have been omitted from this review. Among these are the unsaturated polyesters, melamines, ureas, and the vinyl esters. Although these products do find their way into aerospace applications, the uses are so small that a detailed discussion is not warranted. 

Plastics, particularly polymer-based composites (both thermoplastic and thermoset composites), have been exploited in transportation appUcations for decades. The use of common composites such as glass or carbon fiber reinforced unsaturated polyesters, epoxy, and poly(vinyl ester) matrices is well known. The unique advantage of composites is their strength (tensile strength 4-6 times that of steel) and stiffness, despite their lightweight. 

The most widely used and least expensive polymer resins are the polyesters and vinyl esters. These matrix materials are used primarily for glass fiber-reinforced composites. A large number of resin formulations provide a wide range of properties for these polymers. The epoxies are more expensive and, in addition to commercial applications, are also used extensively in PMCs for aerospace applications they have better mechanical properties and resistance to moisture than the polyesters and vinyl resins. For high-temperature applications, polyimide resins are employed their continuous-use, upper-temperature limit is approximately 230°C (450 F). Finally, high-temperature thermoplastic resins offer the potential to be used in future aerospace applications such materials include polyetheretherketone (PEEK), poly(phenylene sulfide) (PPS), and polyetherimide (PEI). 

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