NOMEX® meta-aramid, poly(meta-phenyleneisophthalamide),
is prepared from meta-phenylenediamine and
isophthaloyl chloride in an amide solvent. It is a long
chain polyamide in which at least 85% of the amide
linkages are attached directly to two aromatic rings. The
meta oriented phenylene forms bends in the polymer
chain, reducing chain rigidity as compared to the para
orientation in the chemically similar KEVLAR® paraaramid
chain. This flexible polymer chain gives
NOMEX® more textile-like qualities while retaining
high temperature properties similar to KEVLAR®.
The aromatic rings and the conjugated amide bonds that
link them together are particularly strong and resistant to
chemical attack. They also provide a high degree of heat
resistance to the polymer backbone. As a result, NOMEX®
does not melt and drip, and merely chars when exposed to
high temperatures for prolonged periods.