Process for preparation of high molecular weight, optionally branched polyarylene sulphides

In the process for the preparation of branched or unbranched polyarylene sulphides which comprises reacting:

• a) 50-100 mol % of dihalogenoaromatics of the formula ##STR4## and 0-50 mol % of dihalogenoaromatics of the formula ##STR5## in which X represents halogen in the meta- or para-position relative to one another, and
• R.sup.1 and R.sup.2 is identical or different and is hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.5 -C.sub.10 -cycloalkyl, C.sub.6 -C.sub.10 -aryl, C.sub.7 -C.sub.10 -alkylaryl or C.sub.7 -C.sub.14 -aralkyl, or two radicals R.sup.1 in the ortho-position relative to one another linked to form an aromatic ring or a heterocyclic ring containing up to three hetero atoms, and wherein one radical R.sup.1 is always other than hydrogen,
• b) 0-5 mol %, based on the sum of the dihalogenoaromatics of the formula I and II, of a tri- or tetrahalogenoaromatic of the formula
• ArX.sub.n (III)
• wherein
• Ar is an aromatic C.sub.6 -C.sub.14 radical or a heterocyclic radical with 5 to 14 ring atoms with up to 3 ring carbon atoms replaced by hetero atoms, X represents halogen, and
• n represents the number 3 or 4, and
• c) 50 to 100 mol % of an alkali metal sulphide or alkali metal sulphide with or without alkali metal hydroxide, and 0 to 50 mol % of an alkali metal bisulphide with the molar ratio of (a+b):c in the range from 0.75:1 to 1.25:1,
• wherein the improvement comprises adding to the reaction 0.1 to 5 mol % of monochlorodiphenyl sulfone.