Vinyl ester resins Applications

In most applications, polyester and vinyl ester resins are used as the matrix materials. Epoxies are also used, although they require longer cure times and do not release easily from the pultrusion dies. Hence, thermosetting resins are most commonly used with pultrusion, although some high-performance thermoplastics such as PEEK and polysulfone can also be accommodated. In addition to the resin, the resin bath may contain a curing agent (initiator, cf. Section 3.3.1.2), colorants, ultraviolet stabilizer, and fire retardant. 

For commodity applications, there are four major classes of resins that are used in FRP applications. They are phenolic resin, epoxy resin, unsaturated polyester resin, and epoxy vinyl ester resins. A more complete description of these types of resins and their many variations can be found in Handbook of Thermoset Plastics. This is not a comprehensive list of resins used in composite manufacture, as commodity materials like polyurethanes and isocyanurate resins are sometimes used as well to make FRP parts. However, these materials are not covered in this chapter owing to their limited use, but, the principals of fire safety that apply for the resins described subsequently apply to these materials as well. 

Waste incineration requires sophisticated scrubbers to contain corrosive volatiles which are in contact with the scrubber wall at elevated temperatures reaching 220°C. " Glass mat reinforced novolac epoxy vinyl ester resins have good performance in this application except that they are subjected to thermal stress due to the temperature difference between surface and wall, and they frequently crack. In order to improve performance, a two layer laminate was produced. The base layer is composed of resin reinforced with glass mat. The resin contains 15-20% graphite filler. The surface layer contains 100 g/m" of carbon fiber. The presence of these two fillers helps to distribute heat more evenly throughout the layer of laminate and prevents cracking even under extreme conditions. "... 

Vinyl ester resins (VERs, epoxy methacrylates) are a major class of styrenated, free radically curable, corrosion- and chemical-resistant thermoset resins. They are largely used in fiber-reinforced structural applications, and they have a substantial history of long-term service in numerous environments at elevated temperatures and pressures, usually under load. 

Mild steel may be suitable as a material of construction for handling caustic soda at ambient temperature. At elevated temperatures, >60°C (140°F), corrosion may occur. Nickel and/or its alloys are most suitable for caustic handling at all temperatures and concentrations, including anhydrous molten caustic up to 480°C (896°F) (Leddy et al. 1978). Polypropylene, fluorocarbon plastics, and flberglass/vinyl ester resins are being used for many applications. Aluminum, tin, zinc, and other amphoteric metals should not be used in construction materials. 

Granular polymer nanocomposites have also been investigated for possible GMR applications [43,96]. Conductive iron nanoparticle-reinforced vinyl ester resin nanocomposites are observed to possess MRs of only 0.9%, which increase to 1.7% after... 

This is one of the most important natural fibers. It is produced in India, Bangladesh, Thailand, Vietnam, and other countries. It contains 56-64 wt% cellulose, 29-25% hemicellulose, 11-14% lignin, and a small proportion of fats, pectin, ash, and waxes. Application of jute fiber in RPs with matrices of TS resins such as unsaturated polyester or vinyl ester resins has been widely studied. To date the poor adhesion to hydrophobic TPs, such as polyethylene and polypropylene, has to date limited application in TPs. 

Conventional vinyl ester resins are increasingly used in anticorrosion applications and in marine applications. They are essentially epoxy resins, but chemically modified to enable them to cure in just the same way, and with virtually the same chemicals and fabrication procedures as polyesters. They have excellent water resistance and chemical resistance, but poor resistance to UV light, although modifications can be made to make them light stable and suitable for use in weatherable gelcoats [13]. 

In all cases, the resins used were Derakane epoxy vinyl esters (Fig. 9.4). In 64% of the cases the resin was one of the higher temperature type, that is an epoxy novolac vinyl ester resin (Derakane 470). This resin is particularly effective in containing acids and organic solvents. Its HDT of 150°C renders it the resin of choice for the higher temperature applications. Bisphenol A epoxy vinyl ester resins (Derakane 411) were used for 25% of the vessels, in particular for the high pH caustic and hypochlorite streams. The brominated epoxy vinyl esters (Derakane 510) were used for the remainder (11%) of the GRP vessels. These resins are important when both fire... 

Atta A.M., El-Saeed S.M., Farag R.K., New vinyl ester resins based on rosin for coating applications. React. Fund Polym., 66(12), 2006, 1596-1608. 

Vinyl ester resins derived from phenolic novolac epoxies are suitable for solvent resistant applications and use at higher service temperatures but have lower failure elongations of about 3%. 

Large towers have carbon steel shells. Brick linings, a standard in the past, are still widely used. These usually comprise two courses of acid-resistant brick held in place over a suitable protective membrane. Vinyl ester resins are suitable for the membrane and the mortar that holds the assembly together. Many systems use unlined carbon steel in the last (driest) stage. Other linings have begun to find some application these include... 

Krigbaum [12] has reported on the use of glass fibre reinforced composites, both from Cytec Industries, based on Cyglas 685 unsaturated polyester [bulk moulding compound (BMC)] and Cyglas 695 vinyl ester resin (BMC) in automotive valve covers and other engine cover applications. The recycling of these valve covers is also discussed. 

While epoxy resins are known for excellent chemical resistance properties, the development and commercialization of epoxy vinyl ester resins in the 1970s by Shell and Dow offered enhanced resistance properties for hard-to-hold, corrosive chemicals such as acids, bases, and organic solvents. In conjimction with the development of the structural composites industry, epoxy vinyl ester resin composites found applications in demanding environments snch as tanks, pipes and ancillary equipment for petrochemical plants and oil refineries, automotive valve covers, and oil pans. More recently, epoxy and vinyl esters are used in the construction of windmill blades for wind energy farms. Increasing requirements in the composite industries for aerospace and defense applications in the 1980s led to the development of new, high performance multifunctional epoxy resins based on complex amine and phenolic structures. Examples of those products are the trisphenol epoxy novolacs developed by Dow Chemical and now marketed by Huntsman (formerly Ciba). 

Taillemite S and Pauer R (2009), Bright future for vinyl ester resins in corrosion applications . Reinforced Plastics, 53, 34-37. doi 10.1016/S0034-3617(09)70151-l... 

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. 

U Lehmann-Burgel, Vinyl ester resins for high performance automotive applications (1990). 

Vinyl ester resins, like epoxy resins, are composed of a large number of different polymers. It is possible to compound these resins to provide properties to meet the requirement of most applications. There are formulations available that will provide resistance to normal atmospheric pollution as shown in Table 8.6, whereas Table 8.7 gives the operating temperature range of the vinyl esters. 

Three basic resins are used—isophthalic polyester, which is the least expensive and is used in most general applications for which it is not necessary for the material to have fire-retardant properties isophthalic polyester resin with a fire-retardant additive that has the same general properties and area of application as the basic isophthalic resin and vinyl ester resin, which is the most expensive but has the greatest corrosion resistance, superior strength and physical properties, and is also fire-retardant. These materials are resistant to most corrodents found in the atmosphere and to a wide range of materials that may spill on the surface. Complete corrosion resistance properties can be found in Corrosion Resistance Tables, 4th ed., published by Marcel Dekker. 

An important application for rubber modified polyester resins is in short-fiber reinforced molding compounds. Specific applications within the automotive industry include grill-opening panels and various car and truck body panels. Rubber modified vinyl ester resins are used as adhesives and as primer coatings for storage tanks. 

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