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It is made from ω-aminolauric acid or laurolactam monomers, and the repeating units each have 12 carbons, hence the name ‘Nylon 12’.

Synthesis
Nylon-12 can be produced through two routes. The first being polycondensation of ω-aminolauric acid, a bifunctional monomer with one amine and one carboxylic acid group.

n NH2(CH2)11CO2H → [(CH2)11CONH]n + H2O

The second route is ring-opening polymerization of laurolactam at 260-300˚C. In this case, laurolactam is hydrolyzed and converted into ω-aminolauric acid, which then undergoes polymerization by condensation. Ring opening can be carried out by cationic or anionic initiators, although cationic initiators have not been used commercially due to the product being less stable and oxidized relatively quickly in comparison to those produced by activated anionic polymerization (monomer casting). This is the preferred route for commercial production as the reaction control is easier and the properties of the product are better.

n N [(CH2)11CONH] + H2O → n NH2 (CH2)11CO2H → [(CH2)11CONH]n + H2O

Properties
Nylon-12 exhibits a combination of properties typical of nylon and polyolefins. Nylon-12's melting point, 178-180˚C, is the lowest among the important polyamides. Its mechanical properties, such as hardness, tensile strength, and resistance to abrasion, are similar to nylon-6 and nylon-66. Low water absorption and density, 1.01 g/mL, result from its relatively long hydrocarbon chain length, which confers it dimensional stability and an almost paraffin-like structure. It is also chemical resistance and not sensitive to stress cracking.

Applications
Nylon 12 has a broad range of applications as polyamide additives, such as plasticizers, crystallization promoters, pigments, and heat and light stabilizers, which can be added either during or after polymerization to modify the product. Nylon 12 is mainly used for films for packing material in the food industry and sterilized films and bags for use in the pharmaceutical and medical fields. When added to polyethylene films, it improves water vapor permeability and aroma impermeability. It is also prepared as sheets and sintered powder for coating metals. In the electronics field, it is used for covering cables and as insulating material, while in the automobile industry it is used to prepare oil and gasoline resistant tubes. In the cosmetic and personal care industries it is used as bulking and opacifying agents in face and body powders. Nylon 12 has also found uses in the textile industry and for producing sporting and leisure goods among other applications.