TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The solid filler material is aluminum trihydrate, magnesium hydroxide, talc, carbon fiber, carbon powder, metallic particulate and/or ceramic particulate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The solvent with the polyunsaturated hydrocarbon comprises: myrcene, vinylcyclohexene, vegetable oil, cyclooctatetraene, or cyclododecatetraene.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The composition further comprises: tetrabromo-vinylcyclohexane, where the ethylene propylene ethylidene norbornene rubber polymer is present in an amount of 0.1-75 wt.%; and a solid filler material. Preferred Method: When the solvent with the polyunsaturated hydrocarbon comprises vinylcyclohexene, then the process (a) further involves brominating the vinylcyclohexene in-situ with the ethylene propylene ethylidene norbornene rubber polymer (0.1-75 wt.%). The method further involves adding a solid filler material into the solvent or into the flame retardant brominated rubber polymeric composition. The step of dissolving the ethylene propylene ethylidene norbornene rubber polymer in the solvent with the polyunsaturated hydrocarbon is performed at 20-60 degrees C. The bromine is added as a pure component or as a solution to brominate the ethylene propylene ethylidene norbornene rubber polymer, where during bromination the temperature is maintained below 30 degrees C. Preferred Components: The bromine is covalently bonded to ethylidene norbornene within the ethylene propylene ethylidene norbornene rubber polymer, and/or propylene within the ethylene propylene ethylidene norbornene rubber polymer. The ethylene propylene ethylidene norbornene rubber polymer is a liquid; and has a glass transition temperature of -60 degrees C to 25 degrees C. The ethylene propylene ethylidene norbornene rubber polymer has a number average molecular weight of 500-20000 Daltons. EXAMPLE - A liquid ethylene propylene ethylidene norbornene rubber polymer (100 g) was dissolved in hexane (500 g) with myrcene (20 g). The dissolution was performed in a reaction vessel at 20-60 degrees C. Bromine ether was added as a pure component or as a solution to cause bromination of the liquid ethylene propylene ethylidene norbornene rubber polymer. The reaction temperature was maintained below 30 degrees C by slowly adding the bromine ether, and externally cooling the reaction vessel. The formed flame retardant brominated rubber polymeric composition had a covalently bonded bromine content of 10-55 wt.%.