Aromatic polyamides. XIII. effect of the halogen position on the thermal and flammability behavior of halogenated poly (1,3‐phenylene‐isophthalamide)

Various halogen substituted poly (1,3‐phenylene‐isophthalamide)s have been prepared. Their glass transition temperature Tg (DSC), thermal decomposition courses (TGA), and flame resistance (oxygen index) are discussed. The polyamides substituted with halogen in the meta position to NH group showed higher Tg and better thermal stability than those substituted with the same halogen in the ortho position. All halogenated polyamides studied had fairly good flame resistance characteristics: high oxygen indices and high char yields. Halogenated aromatic polyamides with nitrogen ortho to halogen showed the flammability characteristic: limiting oxygen index = 38 + 61 × (weight loss at initial plateau temperature).