Bisphenol A diepoxides

The use of blocked isocyanates has proved an important method for cross-linking cathodic electrodeposition coatings (see p. 109). The resin in such a coating might be the reaction product of a bisphenol A diepoxide (with az=4, see p. 176) and diethylamine ... 

Covalent cross-linking of PBI membranes is another possibility for improvement of their thermal, dimensional, and chemical stability. For example, the PBI can be cross-linked in the imidazole moiety with a low-molecular compound such as bisphenol A-diepoxide [15], divinyl sul-fone [16], terephthaldehyde [17], a-dibromo-p-xylene [18], or dichloromethyl phosphonic acid... 

Bisphenol A diglycidyl ether [1675-54-3] reacts readily with methacrylic acid [71-49-4] in the presence of benzyl dimethyl amine catalyst to produce bisphenol epoxy dimethacrylate resins known commercially as vinyl esters. The resins display beneficial tensile properties that provide enhanced stmctural performance, especially in filament-wound glass-reinforced composites. The resins can be modified extensively to alter properties by extending the diepoxide with bisphenol A, phenol novolak, or carboxyl-terrninated mbbers. 

For commercial application, diepoxides such as those derived from bisphenol A are employed, and they are cured via ring-opening crosslinking reactions, into which the epoxy group enters readily. Bisphenol A is so-called because it is formed from two moles of phenol and acetone (Reaction 1.7). 

Selective epoxidation of one of the double bonds in dialkenes is of practical interest (Table XVI). Although monoepoxides predominate at low H2O2 concentrations, the diepoxides are also formed at higher concentrations. The diallyl epoxides of bisphenol A are major intermediates in the adhesives industry, and their synthesis in solid-catalyzed reactions in an eco-friendly manner remains a challenge. 

Figure 14.4 Chemical structures of two common epoxy chain extenders for PET (a) a diepoxide, e.g. Shell Epon 828, based on bisphenol A diglycidyl ether (b) a tetraepoxide, e.g. Ciba MY721, based on tetraglycidyl diaminodiphenyl methane (TGDDM)...

A survey of the extensive literature of kinetic results reported for epoxy-anhydride-tertiary amine systems is surprising. Both nth order and autocatalytic expressions have been reported for the same system. As an example, we analyze the results reported for the copolymerization of a diepoxide based on diglycidyl ether of bisphenol A (DGEBA) with methyl-tetrahydrophthalic anhydride (MTHPA), initiated by benzyldimethylamine (BDMA). 

The principle of miniemulsion polymerization to polyadditions of epoxyresins was successfully transferred to mixtures of different epoxides with varying diamines, dithiols, or diols which were heated to 60°C to form the respective polymers [125]. The requirement for the formulation of miniemulsions is that both components of the polyaddition reaction show a relatively low water solubility, at least one of them even below 10 5 g l1. The diepoxide bisphenol-A-diglycidylether was successfully used as epoxy component. In order to vary the obtained polymeric structure, tri- and tetra-functionalized epoxides were also used. As amino components a NH2 terminated poly(propylene oxide) with Mw=2032 g mol1, 4,4 -diaminobibenzyl, 1,12-diaminododecane, and 4,4 -di-aminodicyclohexylmethane were applied. As other addition components beside amine, 1,6-hexanedithiol and Bisphenol A were used. The hydrophobic compo-... 

In a later study by Dhavalikar and Xanthos [180], the authors investigated di- and tri-functional additives. The diepoxides used were the commercially oriented additives, diglycidyl ether of bisphenol A with molecular weight of approximately 350 (Epon 828) and N,N -bis[3(carbo-2",3 -epoxypropoxy)phenyl]pyromellitimide. Such additives have long been considered to be suitable chain extenders, with their ability to react with carboxyl and hydroxyl end groups ... 

Unmodified epoxy resins vary from the viscous liquid diepoxide 0 (molecular weight 340 and with n = 0 in the general formula above) to solid polymers of molecular weights up to 8000 (n = 26). The resins become solid at molecular weights above 700. While a number of standard grades can be purchased, it is more and more usual for resin producers to take the diepoxide 0 resin, and to react this with bisphenol A to form chain extended epoxy resins in their own resin plant. This process is also termed epoxy advancement. An advantage of this process is that the producer may then introduce other diphenols or hydroxy functional materials to modify the properties of the extended epoxy resin. 

Insertion of a Diepoxide into a Phosphonate Ester. The insertion reaction of bisphenol A diglycidyl ether with diaryl aryl- or alkylphosphonates was shown to give polyphosphonates of moderate molecular weight (114). 

Vinylesters are unsaturated, hence thermosetting, resins, prepared by the reaction of a monofunctional unsaturated acid, e.g. methacrylic, acrylic, crotonic or cynnamic acid, with a bisphenol diepoxide. This type of structure is referred to as bisphenol-A epoxy vinyl ester (Fig. 4.3(a)). The structural difference, which at least partially justihes the improved chemical and mechanical properties of vinylester, is the presence in vinylesters of reactive double bonds at the ends of the chains only, while unsaturated polyester resins have the reactive double bonds distributed throughout the chains. 

An alternative way to obtain vinylester resins is through the novolac epoxy ehemieal structure (Fig. 4.3(b)). In this case, a phenol diepoxide is obtained the novolac backbone structure is particularly suitable for improved resistance to acids in liquid and in vapour form and at higher temperatures than are allowed by bisphenol-A vinylester resins. 

The most common epoxy resins are the reaction products of bisphenol A with excess epichlorhydrin and have the structure shown in Structure 9.5. Because the simple diepoxide... 

Schlack in 1933 (3) reported the first liquid diepoxide from bisphenol-A and an excess of epichlorohydrin ... 

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