Synthesis and flammability of copoly(isophthalamide)s. II. With pendant phosphorus groups

A series of copoly(isophthalamide)s containing pendant phosphorus, dialkoxyphosphinylphenylene, diphenylphosphinylphenylene, and diphenylphosphinylamino groups were prepared. The introduction of phosphorus groups was performed to a degree of ca. 5–17 mol %. From the limiting oxygen index (LOI) measurements, it was found that the LOI of P‐substituted polyamides increased by ca. 14–40%. From TG and DTG analysis the maximum rate and the percentage of mass loss of the decomposition stages were evaluated. From these measurements the mode of action of phosphorus groups in the solid or gas phase was assessed. In the solid phase, due to crosslinking reactions, a reduction of the maximum rate and the percentage of mass loss in the decomposition stage of main chain amide bonds was observed. In this case the increase of the char yield at 700°C of the P‐substituted polyamides was in the range of 21–36%.