Abstract: Block copolymers of vinyl monomers and thioarylene segments are prepared from copoly(arylene sulfide-disulfides), i.e., copoly(arylene sulfides) having an appreciable quantity of disulfide linkages in the polymer chains. Such copoly(arylene sulfides) correspond to the structure [(--A--S--).sub.1-x (A--S--S--).sub.x ].sub.n, wherein X is in the range of 0.5 to 0.001 based on the combined number of (--A--S--) and (A--S--S--) units. In a preferred embodiment n is at least 200; however, polymers and prepolymers having a much lower degree of polymerization can be used, e.g., materials where n is about 25 or higher. To prepare the block copolymers, an unsaturated monomer capable of undergoing free radical addition polymerization under the reaction conditions employed is subjected to such polymerization in the presence of the copoly(arylene sulfide-disulfide) having the above formula. During the course of the polymerization, chain transfer occurs resulting in formation of the block copolymers.

Abstract: Physical properties of filled polypropylene compositions are improved by using a calcium carbonate filler of bimodal particle size, e.g., a mean of 2 microns and a mean of 5 microns, and a polysiloxane additive. The compositions are useful as food containers.

Abstract: Novel higher dialkyl dimethyl ammonium clays, of superior gellant effectiveness in oxygenated organic liquids, can be produced by the overtreatment of layer and chain type mineral clays via ion exchange reactions. For example, a layered dioctadecyl dimethyl ammonium montmorillonite, a superior gellant for alkyd resin based coatings, is prepared by the reaction of sodium montmorillonite with a 12 to 25% excess of the corresponding quaternary chloride beyond the known ion exchange capacity of the clay. The overtreatment is preferably carried out in a mixture of water and organic solvent which disperses the clay and dissolves the quaternary ammonium salt.

Abstract: A silicone elastomer stock that exhibits improved flame resistance in the cured state consisting essentially of a silicone elastomer, a filter, and a small amount of a flame retardant material selected from the group consisting of platinum and platinum-containing materials.