Flammability and thermal behavior of phosphorus‐containing polyamide‐6

An investigation is reported on the flammability and thermal behavior of polyamide‐6, obtained by anionic polymerization of ϵ‐caprolactam, carried out in bulk, in the presence of the following N‐substituted phosphorus‐containing lactam derivatives: diethyl‐(N‐caprolactam)‐phosphonite (PL1), diethyl‐(N‐caprolactam)‐phosphonate (PL2), and 2,5‐dichlorophenyl‐bis(N‐caprolactam)‐phosphinate (PL3). Phosphorus‐containing lactam derivatives PL,1 and PL3 are used as activators of the anionic polymerization of ϵ‐caprolactam, and PL2, as a modifying additive. The phosphorus‐containing polyamide‐6 possesses improved flame retardancy, as well as improved thermo‐ and thermooxidative resistance. Destruction kinetics were studied in nitrogen and air atmospheres, and the activation energy for thermal and thermooxidative destruction have been determined. The effect of PL1 PL2, and PL3 on the melting temperature (Tm) and glass‐transition temperature (Tg) of polyamide‐6 was established.