Vinyl ester resins Properties

MVR 8000 - Good corrosion resistance and physical properties. An economic choice where the optimum vinyl ester resin properties are not required. - Non lire retardant. 

Vinyl ester resins generally offer mechanical properties superior to those of polyester matrices but at an increased cost. Vinyl esters are chemically similar to epoxy resins but are manufactured via a cold-curing process similar to that used in the manufacture of polyester resins. Vinyl esters offer superior resistance to water and chemical attack and are used in such appHcations as underground pipes, tank liners, and storage tanks (see Vinyl polymers). 

In the same way, ABS acts as a toughener for vinyl ester resins (34). Assessment of the mechanical properties suggest that a chemical reaction may have occurred between the constituents of the blends. The blends are intended as a toughening agent for interlayer toughened vinyl ester/glass composite materials. 

TABLE 1. PROPERTIES OF TYPICAL UNCURED VINYL ESTER RESINS... 

Epoxy vinyl ester resins are a special class of unsaturated resin. This resin is made by capping an epoxy resin with methacrylic acid and then dissolving in styrene monomer to the desired viscosity. This gives mechanical properties similar to epoxy resins, but the processibility (low viscosity allowing for resin infusion processes) of an unsaturated polyester resin. As with unsaturated vinyl esters, the most common fire retardant vinyl ester resin is based on a resin made from a halogenated system, tetrabromobisphenol A. The level of bromine in the resin and the presence of antimony will determine the fire performance of the resin. These resins are normally used for corrosion resistant equipment or when fire performance and high mechanical properties are required. It is very difficult to get a low smoke value with a brominated vinyl ester resin again due to the fact that bromine... 

To overcome these drawbacks, in recent years much attention has been paid to the development of resins which cem be f2d ricated with the same processes as those for conventional polyester resins, but having superior properties. Vinyl ester resins are the result of such development efforts (4-6). Vinyl ester resins are addition products of Vcurious epoxide resins and ethylenically unsaturated mono-carboxylic acids ( ). It condsines the excellent mechcuiical, chemical cuid solvent resistemce of epoxy resins with the properties found in the unsaturated polyester resins. In general, the cured vinyl ester resin has physical properties superior to the cured conventional ester resin, particulcurly corrosion resistcuice. This arises from the differences in the number and arremgement of polar groups such as ester and hydroxyl groups eind ccurbon-to-ccirbon double bonds present in the polymer chains. 

The chemical reactivities of the unsaturated groups at the ends of vinyl ester resin and vinyl urethane resin chains are different in several respects from those of the same groups when situated in mid-chain positions, as they are in polyester resins. As a consequence of the different reactivity ratios, the two kinds of cured resin behave differently from moisture and chemical resistance points of view. The structural differences are also reflected in the mechanical properties, such as fracture toughness. 

Epoxy vinyl ester resins are the resin of choice for industrial corrosion-resistant GRP equipment and the leading supplier is the Dow Chemical Company, with its brand name of Derakane . Some properties of various resin families are given in Table 9.1. 

Chem. Descrip. MEK peroxide in dimethyl phthalate Uses Curing agent for reduced gas generation in vinyl ester resin-based gel coals, bamer coatings, and corrosion resist, constniction Properties Clear liq. act. oxygen (9%)... 

Zia Ziaee, S., Palmese, G. R. Effects of temperature on cure kinetics and mechanical properties of vinyl-ester resins. J. Polym. Sci. B Polym. Phys. 37 (1999) 725-744. 

Kar Karger-Kocsis, J., Gryshchuk, O. Morphology and fracture properties of modified bisphenol A and Novolac type vinyl ester resins. J. Appl. Polym. Sci. 100 (2006) 4012-4022. 

Unsaturated polyesters contain a relatively high number of double bonds per polymer molecule as well as reactive end groups which remain unreacted after the cross-linking reaction. These unreacted groups have a negative effect on the network properties. These unfavorable structural defects are largely eliminated in what is known as vinyl ester resins ... 

Typical properties of vinyl ester resins are given in table 3.3. 

The vinyl ester resins have properties that are intermediate between polyesters and epoxides, are easier to process than epoxides, coupled with a better chemical resistance than polyester resins. 

Alpha Owens-Coming offers a flame retardant vinyl ester resin that meets ASTM 84 Class 1 flame spread and smoke rating. The resin is a highly brominated bisphenol-A epoxy based vinyl ester. It provides a unique combination of good flame and smoke resistance and inherently good mechanical properties. The flexural strength of 34% glass composite is 5100 psi (35 MPa) and flexural modulus is 450 ksi (3.1 GPa). 

Vinyl ester resins The vinyl ester resins are essentially epoxide resins, normally the digly-cidyl ether of bisphenol A, that have been reacted with acrylic acid or its derivatives. The unsaturation in the acid residues provides sites for a cross-linking mechanism based on free radical polymerization. The retention of the bisphenol A backbone in the chain of the cross-linked polymer conserves most of the mechanical and physical properties associated with the parent epoxy. The resins thus provide a combination of ease of processing with good chemical resistance and mechanical behaviour. 

Guo, Z., Liang, X., Pereira, T., Scaffaro, R., Hahn, H.T. CuO nanoparticle filled vinyl-ester resin nanocomposites fabrication, characterization and property analysis. Compos. Sci. Technol. 67, 2036-2044 (2007)... 

They have easy processing properties, much like a polyester resin. In their uncured state vinyl ester resins also have physical properties similar to those of polyesters, but once crosslinked, vinyl esters have much greater strength, stiffness, and toughness than conventional polyester resins, particularly when exposed to corrosive chemicals. Vinyl esters are noted for their resistance to water and chemicals at both room and elevated temperature. 

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