Salt Byproduct Separation During Formation of Polyarylene Sulfide

A method for forming a polyarylene sulfide comprising:

• reacting a dihaloaromatic compound with an alkali metal sulfide or an alkali metal hydrosulfide in an organic amide solvent to form a polyarylene sulfide and a salt;
• subjecting a mixture including the polyarylene sulfide, the salt, and the organic amide solvent to a filtration process in which the mixture flows to a filter medium from upstream of the filter medium and in which a filtrate flows away from the filter medium in a downstream direction, the salt being retained on the filter medium during the filtration process and forming a filter cake, the filtration process having a downstream pressure, the downstream pressure being elevated above atmospheric pressure, the boiling temperature of the mixture at the downstream pressure being greater than the minimum temperature at which the polyarylene sulfide is fully soluble in the solvent, the filtration having an upstream pressure, the upstream pressure being greater than the downstream pressure for at least a portion of the filtration process, the filtration being carried out in a temperature range that is less than the boiling temperature of the mixture at the downstream pressure and that is greater than the minimum temperature at which the polyarylene sulfide is fully soluble in the solvent.