Amine Curing

Halobutyl Cures. Halogenated butyls cure faster in sulfur-accelerator systems than butyl bromobutyl is generally faster than chlorobutyl. Zinc oxide-based cure systems result in C—C bonds formed by alkylation through dehydrohalogenation of the halobutyl to form a zinc chloride catalyst (94,95). Cure rate is increased by stearic acid, but there is a competitive reaction of substitution at the halogen site. Because of this, stearic acid can reduce the overall state of cure (number of cross-links). Water is a strong retarder because it forms complexes with the reactive intermediates. Amine cure may be represented as follows ... 

Reduction in compression set began to be achieved in the late 1960s when it was found that tropolene and phenanthroline not only accelerated amine cures but were also effective with certain bisnucleophiles such as resorcinol, hydroquinone and bis-phenol AF. In due course even better results were obtained with quaternary ammonium or phosphonium salts being used in conjunction with aromatic dihydroxy compounds. 

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... 

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... 

For resistance to acid conditions alone, traditional filled and unfilled bituminous solutions (which have economic advantages), chlorinated rubber and shellac have been used. Crosslinking coatings, e.g. amine-cured epoxy resins, often blended with coal-tar which develops resistance to oils and solvents, have obvious advantages on chemical plant. 

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. 

Figure 1. Three main epoxy - amine curing reactions.

Figure 2. Mechanism and reaction rates for the epoxy - amine cure.

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. 

Epoxy (Amine-Cured) Bisphenol A-based epoxy resins used for composite fabrication are commonly cured with multifunctional primary amines. For optimum chemical resistance these generally require a heat cure or postcure. The cured resin has good chemical resistance, particularly to basic environments, and can have good temperature resistance. 

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

Polystyrene insulation on magnet wire 0.29 Encapsulated with B-staged aromatic amine cured aliphatic amine cured bisphenol A-epichlorohydrin epoxide (epoxy transfer moulded). Impregnate. 

Figure 5. Hypothesized network structure in amine-cured bisphthalonitrile polymers.

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... 

Fourier transform Infrared spectroscopy has been shown to be an excellent tool for surface and Interface studies (.2), In this paper, the application of reflection/absorption Fourier transform Infrared spectroscopy (FTIR-RA) for studying the degradation of amine-cured epoxy and polybutadiene coatings on cold-rolled steel after exposure to a warm, humid environment is reported. 

The amine-cured epoxy used was from a formulation containing ... 

Degradation of Amine-Cured Epoxy Coating on Cold-Rolled Steel... 

FTIR-RA spectra of the amine-cured epoxy coating on cold-rolled steel before and after exposure at 40°C and 80% RH are shown In... 

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