Curing agents amine

Aliphatic and cycloaliphatic amine curing agents irritants, sensitizers, corrosive, absorbed through skin, respiratory irritants high toxicity... 

Aromatic amine curing agents sensitizers, longterm health effects, absorbed through skin respiratory irritants sensitizers moderate to high toxicity... 

By contrast with tertiary amines used in catalytic quantities, primary and secondary amines or acid anhydrides may be used to bring about the cure of epoxy resins by reaction in stoichiometric proportions. A typical amine curing agent used at this level is diaminodiphenylmethane (DDM), which reacts with an individual epoxy-group in the way shown in Reaction 4.17. 

Thus with industrial skin sensitizers, e.g. chromates or amine curing agents, no effect is usually observed on first exposure subsequent exposure results in inflammation of the skin, not restricted to the areas of contact. Refer to Table 4.5. 

Amine cured systems, primary and secondary, 70 418 Amine curing agents, commercial,... 

Epoxy resins. The reaction of Bisphenol A and epichlorohydrin gives a low molecular weight linear polymer. This polymer further reacts with an amine-curing agent, R-NH2, to give a general-purpose thermoset. See Figure 24-2.) Now that s not as complicated as it sounds. First of all, you d think... 

Fig. 3.10. Effect of curing cycle on the fraction of amine curing agent estimated to have diffused out of droplets as a function of their size. After Rao et al. (1991).

Fig. 3. Bpoxy heterogeneities as a function of amine curing agent content determined by two different methods. The upper series were microtomed samples stained with osmium tetroxide and the lower series were plasma treated fracture surfaces. Both methods gave size and distribution values for the heterogeneities which agreed qualitatively...

To attain the requirements of an epoxy matrix utilized in filament-wound C-fiber-epoxy composites we have considered the characteristics required of the amine curing agent molecule. To ensure long gel times at 23 °C requires that the primary amine-epoxide (P.A.-E) reaction rate is considerably greater than the rate of the secondary amine-epoxide (S. A.-E) reaction, and that the S.A. reaction does not occur at low temperatures. Furthermore, to attain low 23 °Cr s and low post-cure temperatures... 

Fig. 5. Schematic diagram for the process of surface graft polymerization of GMA onto GA and subsequent reaction with amine curing agent in EMC...

Uncoated iron Cellulose acetate butyrate Epon 828/V125 Epoxy amine curing agent Shell/General... 

Amines are one of the most important curing agents for epoxy resins. They provide fast cures with a relatively high crosslink density. Unmodified amine cured epoxy resins are generally too brittle for adhesive applications, and so there are many derivatives that have been developed. More information on amine curing agents can be found in Chap. 5. 

Procedure for calculating the stoichiometric quantity of amine curing agent... 

FIGURE 5.5 Chemical structures of common aromatic amine curing agents. 

When used with primary amine curing agents, reactivity is reduced. 

Table 11.12 shows two rapid-setting, room temperature cure epoxy adhesives based on epoxy acrylate resins with aliphatic amine curing agents. These adhesives have gel times of less than 5 min for a 100-g mass. The bond strength development is rapid with handling strength occurring in about 1 h at room temperature. 

Table 12.9 shows a formulation for an accelerated general-purpose one-component, dicyandiamide cured epoxy adhesive compared to one with a modified aliphatic amine curing agent. Notice that the dicyandiamide cured system provides a higher glass transition tem-... 

DADPS also provides excellent high-temperature properties and chemical resistance. Of the amine curing agents, DADPS provides the best retention of strength after prolonged exposure to elevated temperatures. It melts at 135°C and can be cured with epoxy resins at 20 to 30 pph with cure temperatures ranging from 115 to 150°C. Because of the low reactivity of this system, an accelerator, such as BF3-MEA, is usually employed at about 1 pph. 

It has been shown that tensile shear and peel strength for several latex polymers (ethylene vinyl acetate, polyvinyl alcohol, ethylene vinyl chloride, polyvinyl chloride, and acrylic) can be significantly increased by the addition of 10 percent by weight of an epoxy emulsion cured with a tertiary amine curing agent.17 The epoxy modification improves the bond strength in all cases. The degree of improvement is dependent on the selection of the latex type and the chemistry of the latex polymer. 

For maximum heat resistance, pyromellitic dianhydride is often used. The composition and properties of metal-to-metal adhesives based on a combination of epoxy novolac and a bisphenol A epoxy resin have been described in Sec. 12.5.1. Depending on the cure temperature and the choice of amine curing agent, strength as high as 3000 psi at room temperature and over 1000 psi in the range of-55 to + 150°C is possible. 

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