Melt viscosity stabilizers for vinyl chloride polymers

A method for stabilizing the melt viscosity of vinyl chloride polymer compositions said method consisting essentially of incorporating into said composition between 0.1 and 10%, based on the weight of the vinyl chloride polymer, of a linear polysulfide of the general formula A.sub.x (S.sub.z).sub.y wherein each A is individually selected from the group consisting of elements exhibiting an atomic weight of between 6.9 and 209, inclusive and a valence v, the elements being in turn selected from groups I-A, I-B, II-A, II-B, III-A, IV-B, V-A, VI-B, VII-B and VIII of the periodic table, tin and lead, wherein x is 1 when v is even and x is 2 when v is odd, y is 1 when v is 1 or 2, y is 2 when v is 4 and y is equal to v when v is 3 or 5, and z is an integer between 3 and 8, inclusive.