Curing Agents for Epoxy Systems

Adducted aliphatic polyamines offer the advantages of lower vapour pressure, reduced blush tendency, and less-critical mix ratios. 

Aromatic amines are solids at room temperature and are routinely melted at elevated temperatures and blended with warmed resin. Eutectic mixtures of metaphenylene and methylene dianiline exhibit a depressed melting point, producing an aromatic hardener that remains liquid over short periods of time. Pot life is considerably longer that that of aliphatic polyamines. Cure at elevated temperature is needed to develop optimum properties, which are maintained at up to 15()°C. Aromatic amines have better chemical and thermal resistance than aliphatic polyamines. 

The various molecular weight polyamides show different degrees of compatibility with epoxies. To ensure optimum properties the polyamide/epoxy mixture must be allowed to react partially before being used. This partial reaction assures compatibility and is known as the induction period. Because polyamides have a long pot life, the induction time does not significantly shorten the usable time of the system. 

Polyamide-cured epoxies lose structural strength rapidly with increasing temperature, limiting their use to applications that will not be subjected to temperatures above 65°C. 

Amidoamines are derivatives of monobasic carboxylic acid (such as ricinoleic acid) and an aliphatic polyamine. Like the polyamides, amidoamines can be used 

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