Process for the production of optionally branched polyarylene sulfides

A process for the production of an optionally branched, high molecular weight polyarylene sulfide having a high melt viscosity, comprising reacting in the presence of a reducing agent selected from hydrazine, alkali metal borohydrides, alkali metal formates;

• a mixture of
• (a) from 100 to 0 mole percent ##STR6## and from 0 to 100 mole percent ##STR7## where the sum of (I) and (II) is 100 mole percent, and where each X is independently chlorine or bromine in the meta or para position to one another and where each R.sup.1 is independently hydrogen, an alkyl containing from one to twenty carbon atoms, a cycloalkyl containing from five to twenty carbon atoms, an aryl containing from six to twenty-four carbon atoms, an alkaryl containing from seven to twenty-four carbon atoms, or an aralkyl containing from seven to twenty-four carbon atoms, where two of R.sup.1 in the ortho position to one another may be attached to form an aromatic or 6-membered heterocyclic ring containing up to 3 heteratoms, and where one of R.sup.1 is always different from hydrogen;
• and
• (b) from 0 to 3.0 percent, based on the sum of (I) and (II), of an aromatic trihalogen or tetrahalogen compound
• ArX.sub.n
• where Ar is an aromatic or heterocyclic moiety having from six to twenty-four carbon atoms and up to 3 heteroatoms, X is chlorine or bromine, and where n is 3 or 4;
• (c) an alkali metal sulfide, in a molar ratio (a+b):c of from 0.85:1 to 1.15:1;
• and
• (d) at least one polar solvent, in a molar ratio of c:d of from 1:2 to 1:15.