Epoxies glycidyl amine

Glycidyl amine epoxy resins are reaction products of aromatic amines and epichlorohy-drin. They have high modulus and high glass transition temperature. These resins find use in aerospace composites and high-temperature adhesive formulations. 

Aromatic and Heterocyclic Glycidyl Amine Resins. Among the specialty epoxy resins containing an aromatic amine backbone, the following are commercially significant. 

Resinous adducts, 10 394 Resinous odor, 3 229t Resins. See also Epoxy resins Lacquer resins Novolac resins Phenolic resins Resole resins Thermoplastic resins acidic cation-exchange, 12 191 advanced materials, 1 693 antilipemic agents, 5 141 aromatic glycidyl amine, 10 372—373 chromatographic, 14 383-384 for coatings, 7 95-107 derived from furfuryl alcohol, 12 271— 272... 

In adhesive formulations, aliphatic amines are most commonly used to cure the DGEBA type of epoxy resin. Aliphatic amines are not widely used with the non-glycidyl ether resins, since the amine-epoxy reaction is slow at low temperatures. The reaction usually requires heat and accelerators for an acceptable rate of cure. Aliphatic amines are primarily used with lower-viscosity DGEBA resins because of the difficulty in mixing such low-viscosity curing agents with the more viscous epoxy resins. 

The work described herein relates primarily to lamination and bonding processes. However, the techniques are generic to most forms of thermoset resin processing. In the discussion which follows many of the resin systems contain glycidyl amines. The bulk of the epoxy formulations used in the aerospace industry today are based on tetraglycidylmethylenedianiline, I (TGMDA) and with diaminodi phenylsulfone, II (DOS). Systems based on... 

As far as the addition of aniline to the ACECs is concerned, the principal conclusions in [50] were confirmed glycidyl type epoxy groups are more reactive than those attached to the cyclohexane ring. Moreover, there is a very distinct induction period in the case of glycidyl groups. The appearance of the induction period is connected with the accumulation of hydroxyl groups which serve as an accelerator of the epoxy-amine addition. This acceleration effect is little noticeable as far as cycloaliphatic epoxy groups are concerned. 

High conversion of cycloahphatic epoxy groups in the triepoxide ACECs on curing with aromatic amines is noticeable. This phenomenon can be attributed to the catalytic effect of secondary hydroxyl groups being formed as a result of the glycidyl-amine addition as well as - to a lesser extent - the increase in reactivity as discussed above. All this secures an increased mechanical strength and heat resistance of cured ACECs (Table 9). 

Another commercially important aromatic glycidyl amine resin is trigly-cidyl isocyanurate (TGIC), which is discussed in the Weatherable Epoxy Resins section. 

By reacting epichlorohydrin with aromatic diamines, it is possible to manufacture epoxy resins with higher functionality than DGEBA or DGEiBF resins. As shown in Fig. 5.9, the structure of tetraglycidyl methylene dianiline epoxy, the most important glycidyl amine, is characterized by four epoxy... 

There are two main categories of epoxy resins glycidyl epoxy, and non-glycidyl epoxy. The former are further classified as glycidyl-ether, glycidyl-ester and glycidyl-amine. 

Multifunctional epoxy resins such as aromatic glycidyl ether resins and aromatic glycidyl amine resins are commercially available. Commercially important epoxy phenol Novolac resins and epoxy cresol Novolac resins are prepared from excess epichlohydrin and phenol-formaldehyde or o-cresol-formaldehyde resins. The high functionality of these Novolac resins increases crosslink density and improves thermal stability and chemical resistance ... 

Epoxy resins derived from multifunctional aromatic glycidyl amine resins such as triglycidyl-p-aminophenol and tetraglycidyl-4,4 -diaminodiphenylmethane have excellent properties at elevated temperatures ... 

Low-molecular-weight model compounds such as phenylglycidyl or other mono-glycidyl ethers as well as primary, secondary and tertiary amines have been used for the study of the kinetics, thermodynamics and mechanism of curing. To reveal the kinetic features of network formation, results of studies of the real epoxy-amine systems have also been considered. Another problem under discussion is the effect of the kinetic peculiarities of formation of the epoxy-amine polymers on their structure and properties. 

Condensation gf phenyl isocyanate has also been reported reoently 88 to occur with phonyl glycidyl other and l,2-epoxy-3-phenylhutane in the presence of catalytic amounts of benzyldimethyl-amine (Eq. 973). 

The use of model compounds is a convenient starting point to determine the reaction path, particularly for stepwise polymerizations. For epoxy-amine systems, a monofunctional epoxide such as phenyl glycidyl ether (PGE) is often used for these studies (Verchere et al., 1990 Mijovic and Wijaya, 1994). Figure 5.10 shows the reaction scheme for the curing of a monoepoxide with a diamine. 

Glycidyl Adducts of Aliphatic Amines. An aliphatic amine such as diethylenetriamine can be partially reacted with an epoxy, such as a DGEBA resin, to produce a low-volatility adduct. In a typical reaction, the epoxy is added slowly to a large excess of DETA. The reaction is maintained at 75°C by cooling. The reaction products are continuously agitated effectively to provide for good contact and uniform concentration effects. At the end of the reaction, excess DETA is vacuum-distilled away from the adduct. 

The commercial flexibilizing reactive diluents are predominantly glycidyl derivatives of glycols, dimerized acids, or reaction products of dicarboxylic acids with epoxy resins. The properties of certain polyepoxy diluents are summarized in Table 8.3. Some of, but not all, these materials provide good reactivity with aliphatic primary amines at room temperature. 

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