Chemical resistance also aromatic polymers

Polyamides Thermoplastic aromatic or aliphatic polymer of dicarboxylic acids and diamines, of amino acids, or of lactams. Has good mechanical properties, chemical resistance, and antifriction properties. Processed by extrusion and molding. Used in fibers and molded parts. Also called PA. 

Mechanical and chemical resistance is equally important with the high-temperature-resistant plastics. This class consists of hydrogen-poor amorphous polymers with a rigid skeleton poly(phenylenes), poly(phenylene oxides), poly(xylylenes), aromatic polyamides, polyamides, poly(benzimi-dazoles), etc. High-temperature-resistant tibers are also made from many of these polymers (see also Chapter 38). 

Both blocked aromatic and aliphatic polymers use latent curatives such as ketimines and oxazolidines however, they do have some inherent disadvantages. The use of ketimines and aldemines often produces products that have a tendency to yellow upon exposure to sunlight, and that take a longer time to achieve complete cure and retain slow evaporating ketones or aldehydes. Oxazolidine modification can also result in some yellowing and reduced chemical resistance to some acids [26]. 

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