polysulfide rubber

:  any of various synthetic rubbers made by the reaction of a sodium polysulfide with an organic dichloride (as ethylene dichloride or a dichloro derivative of ethyl formal), characterized in general by good resistance to oxygen, light, oils, and solvents, impermeability to gases, and poor tensile strength and abrasion resistance, and used chiefly in mechanical rubber goods, in adhesives, binders, and sealing compositions, and in coatings (as for textiles)