Ethers, diglycidyl

Diethylene glycol Ethylene glycol diglycidyl ether 1.445 1.447 1.128 1.134... 

DGEBA. See Bisphenol A, diglycidyl ether. Bisphenol A, diglycidyl ether (DGEBA) [1675-54-3]... 

Numerous avenues to produce these materials have been explored (128—138). The synthesis of two new fluorinated bicycHc monomers and the use of these monomers to prepare fluorinated epoxies with improved physical properties and a reduced surface energy have been reported (139,140). The monomers have been polymerized with the diglycidyl ether of bisphenol A, and the thermal and mechanical properties of the resin have been characterized. The resulting polymer was stable up to 380°C (10% weight loss by tga). 

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. 

Comparable process techniques involving the reaction of bisphenol A diglycidyl ether with methacrylic acid produce the corresponding hydroxy... 

Shell Chemical Company has iatroduced a new tetraglycidyl amine and a new stiff backbone diglycidyl ether under the respective trade names EPON HPT Resia 1071 [103490-06-8] and EPON HPT Resia 1079 [47758-37-2] (8,9), which have superior hot—wet performance compared with TGMDA. These two materials are chemically Ai,Ai,A7,A7-tetraglycidyl-a,aTis(4-aminophenyl)-/)-diisopropylben2ene and... 

Epichlorohydrin and Bisphenol A-Derived Resins. The most widely used epoxy resins are diglycidyl ethers of bisphenol A [25068-38-6] (1) derived from bisphenol A [80-05-7] and epichlorohydrin [106-89-8],... 

The pure diglycidyl ether of bisphenol A [1675-54-3] DGEBA is a crystalline soHd (mp 43°C) with a weight per epoxide (WPE) = 170. The typical commercial unmodified Hquid resins are viscous Hquids with viscosities of 11—16 Pa-s (110—160 P) at 25°C, and an epoxy equivalent weight of ca 188. 

Advancement Process. In the advancement process, sometimes referred to as the fusion method, Hquid epoxy resin (cmde diglycidyl ether of bisphenol A) is chain-extended with bisphenol A in the presence of a catalyst to yield higher polymerized products. The advancement reaction is conducted at elevated temperatures (175—200°C) and is monitored for epoxy value and viscosity specifications. The finished product is isolated by cooling and cmshing or flaking the molten resin or by allowing it to soHdify in containers. 

Gel-permeation chromatography studies of epoxy resins prepared by the taffy process shown n values = 0, 1, 2, 3, etc, whereas only even-numbered repeat units are observed for resins prepared by the advancement process. This is a consequence of adding a difunctional phenol to a diglycidyl ether derivative of a difunctional phenol in the polymer-forming step. 

Bais resin = diglycidyl ether of bisphenol A (wtper epoxide (WPE) = 182-196). 

Diglycidyl Ether of Bisphenol A. The Hquid DGEBPA-based resins exhibit low acute toxicity with a single-dose oral LD q value in rats of >2000 mg/kg (40). The potential for absorption of DGEBPA through the skin in acutely toxic amounts is low. LD q values of >800 mg/kg for acute dermal toxicity have been obtained from studies using both the pure and commercial DGEBPA (41,42). 

The term epoxy is familiar to nonchemists because of the widespread use of epoxy glues and resins. These are crosslinked polyether thermoplastics made from a liquid resin which is typically a mixture of bisphenol A diglycidyl ether (70) and a polymer (71 Scheme 86). The liquid resin is cured or hardened to the final resin by mixing with a crosslinking reagent, which can be an acid, a di- or poly-alcohol, or a di- or poly-amine (Scheme 86). 

Although it would appear, at first glance, that diglycidyl ether would be prepared by a molar ratio of 2 1 epichlorohydrin-bis-phenol A, probability considerations indicate that some higher molecular weight species will be produced. Experimentally it is in fact found that when a 2 1 ratio is employed, the yield of the diglycidyl ether is less than 10%. Therefore in practice two to three... 

Higher moleeular weight products may be obtained by reducing the amount of excess epichlorohydrin and reacting the more strongly alkaline conditions which favour reaction of the epoxide groups with bis-phenol A. If the diglycidyl ether is considered as a diepoxide and represented as... 

Resin viscosity is an important property to consider in handling the resins. It depends on the molecular weight, molecular weight distribution, chemical constitution of the resin and presence of any modifiers or diluents. Since even the diglycidyl ethers are highly viscous materials with viscosities of about 40-100 poise at room temperature it will be appreciated that the handling of such viscous resins can present serious problems. 

The epoxide equivalent is a measure of the amount of epoxy groups. This is the weight of resin (in grammes) containing 1 gramme chemical equivalent epoxy. For a pure diglycidyl ether with two epoxy groups per molecule the epoxide... 

They will be present in the higher molecular weight homologues of the diglycidyl ether of bis-phenol A. 

Table 26.5 Properties of some anhydrides used in low molecular weight diglycidyl ether resins...

Low-viscosity diglycidyl ether resins of undisclosed composition" have been marketed in the United States and in Britain. The materials are stated to be totally difunctional, i.e. free from monofunctional reactive diluents. The cured resins have properties very similar to those of the standard diglycidyl ether resins. 

As a result of the demand for flame-resistant resins, halogenated materials have been marketed. A typical example is the diglycidyl ether of tetrachlorobis-phenol A Figure 26.14). 

Compared with standard diglycidyl ether resins, the liquid cyclic aliphatic resins are paler in colour and have a much lower viscosity. Whereas in general the cyclic aliphatic resins react more slowly with amines, there is less difference with acid anhydrides. Table 26.7 provides data illustrating this point. 

Unox Epoxide 20] Unox Epoxide 206 Unox Epoxide 207 Standard diglycidyl ether... 

Because of the compact structure of the cycloaliphatic resins the intensity of cross-linking occurring after cure is greater than with the standard diglycidyl ethers. The lack of flexibility of the molecules also leads to more rigid segments between the cross-links. 

As a consequence the resins are rather brittle. The high degree of cross-linking does, however, lead to higher heat distortion temperatures than obtained with the normal diglycidyl ether resins. 

The epoxidised polybutadiene resins available to date are more viscous than the diglycidyl ethers except where volatile diluents are employed. They are less reactive with amines but have a similar reactivity with acid anhydride hardeners. Cured resins have heat distortion temperatures substantially higher than the conventional amine-cured diglycidyl ether resins. A casting made from an epoxidised polybutadiene hardened with maleic anhydride and cured for two hours at 50°C plus three hours at 155°C plus 24 hours at 200°C gave a heat... 

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