Degradation kinetics of meta‐ and para‐aromatic polyamides

Poly(m‐phenylenediamineisophthal)amide (MPD‐I) and poly(p‐phenylenediamineterephthal)amide (PPD‐T) are among the most important high‐tech polymers. The degradation of three MPD‐I fibers with different molecular weight distributions and a PPD‐T fiber was studied in a proprietary laboratory degradation chamber. The results were fitted satisfactorily to a kinetic model describing the degradation as a combination of thermal scission, oxidation, and hydrolysis. PPD‐T degradation is slower than that of MPD‐I, and MPD‐I resistance to degradation increases as polydispersity decreases.