Nylons diamines, chemical structures

The manufacture of the large variety of polyamides (commonly referred to as nylons) occurs through polycondensation of amino carboxylic acids (or functional derivatives of them, e.g. lactams) and from diamines and dicarboxylic acids. Labeling the amino groups with A and the carboxyl groups with B allows differentiation of the different chemical structures between the two types AB (from amino carboxylic acids) and AA-BB (from diamines and dicarboxylic acids). The number of C atoms in the monomers acts as a code number for the identification of the polyamides. The polycaprolactam manufactured from caprolactam (type AB) is then called polyamide 6 (PA 6). The number of carbon atoms in the diamine is given first for type AA-BB followed by the number of atoms in the dicarboxylic acid, e.g. PA 66 for polyhexamethylenedia-dipic amide from hexamethylenediamine and adipic acid. For copolymers the components are separated by a slash, e.g. PA 66/6 (90 10) is a copolymer composed of 90 parts PA 66 and 10 parts PA 6. 

As a member of the nylon family, it is a semicrystalline material composed from a diacid and a diamine. However, the diacid portion contains at least 55% terephthalic acid (TPA) or isophthalic acid (IPA). TPA and IPA are aromatic components which serve to raise the melting point and glass transition temperature, and generally improve chemical resistance versus standard aliphatic nylon polymers. The structure of the polymer depends on the ratio of the... 

On February 28, 1935, Carothers project succeeded beyond anyone s wildest dreams. The cheerful, lively Frenchman Berchet produced a superpolymer made from chemicals derived from cheap benzene, a by-product of coal later they would be made from petroleum. A filament teased from Berchet s polymer was, despite its lowly origins, pearly and lustrous. And when it was tested, it proved to be spinnable. Its code name was 6-6 because both its reactants—hexamethylene diamine and adipic acid—had six carbon atoms. Technically, the filament was polyhexamethylene adipamide, a long-chain polymer similar in structure to proteins. It became world-famous as nylon. 

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