Aromatic polyamidoimides having maleimido end groups

A linear aromatic polyamidoimide having maleimido end groups and having the following general formula:

• ##STR13## in which each of the symbols D, which are identical, is a single valence bond or one of the groups:
• ##STR14## the symbol B is a trivalent radical comprising an aromatic radical containing at least 6 carbon atoms, substituted or unsubstituted, or of two such radicals linked together by a
• single valence bond or one of the groups:
• ##STR15## the symbol m is the average number of recurring structural units and is at least equal to 1;
• and each of the symbols X, which are identical, is a radical of the formula:
• ##STR16## in which each of the symbols R.sub.1, R.sub.2, which may be identical or different, is a hydrogen atom or a methyl radical;
• the symbol R.sub.3 is a methyl radical;
• n is an integer equal to 0, 1, 2 or 3;
• and the symbol E is a single valence bond or a --CH.sub.2 -- group and is in an ortho, meta or para position relative to the carbon atom of the benzene ring which is linked to the CONH group.