Abstract: A flame retardant comprising a mixture of 10 to 90% by weight of powder A and 90 to 10% by weight of powder B of magnesium hydroxide, the powder A containing 40 to 70% by weight of a powdered double salt of magnesium carbonate and calcium carbonate and 60 to 30% by weight of powdered basic magnesium carbonate; and a flame-retardant resin composition comprising 100 parts by weight of a thermoplastic resin and 30 to 300 parts by weight of the flame retardant. Preferably, the double salt is huntite, and the basic magnesium carbonate consists essentially of hydromagnesite. It is preferred to treat the flame retardant, in the form of a powder mixture, with a surface treatment agent. The flame-retardant resin composition is adapted for use as a sheath or insulation for an electric wire or cable, a fire-arresting material, or a wall material.

Abstract: A radiation-resistant high molecular composition is disclosed, charqacterized in that, to the high molecular polymer, a halogenated acenaphtylene and/or condensates thereof represented by a following general formula [I] ##STR1## (wherein, X indicates a chlorine or bromine atom, a indicates 0 to 2, b indicates 1 to 6 and n indicates an integer not less than 1) and a diphenyl ether derivative represented by a following general formula [II] ##STR2## (wherein, R.sub.1 and R.sub.2 indicate any ones of hydrogen atom, alkyl, alkoxy, phenyl phenoxy, diphenyloxy and terphenyloxy group) and/or basic lead compound are formulated.

Abstract: A radiation-resistant high molecular composition is disclosed, characterized in that, to the high molecular polymer, a halogenated acenaphtylene and/or condensates thereof represented by a following general formula [I] ##STR1## (wherein, X indicates a chlorine or bromine atom, a indicates 0 to 2, b indicates 1 to 6 and n indicates an integer not less than 1) and a diphenyl ether derivative represented by a following general formula [II] ##STR2## (wherein, R.sub.1 and R.sub.2 indicate any ones of hydrogen atom, alkyl, alkoxy, phenyl phenoxy, diphenyloxy and terphenyloxy group) and/or basic lead compound are formulated.