Thermoplastic polyphenylene oxide compositions such as polyphenylene oxide that has been modified with high impact polystyrene are rendered fire retardant by the addition of an effective amount of a 3-hydroxyalkyl phosphine oxide such as n-butyl bis(3-hydroxypropyl) phosphine oxide.
Polyurethane compositions are rendered fire retardant by substitution of some of the polyol normally present in the reaction mixture by an effective amount of a 3-hydroxypropyl phosphine oxide such as sec-butyl bis(3-hydroxypropyl) phosphine oxide.
A polyphenylene ether resin composition comprising:
(i) from 30 to 90 weight percent of a graft copolymer free from polyphenylene ether homopolymers prepared by polymerizing 20 to 200 parts by weight of styrene-type compound at a temperature in the range from 130°C to 200°C in the presence of 100 parts by weight of polyphenylene ether and 0.1 to 15 parts by weight of a radical initiator and
(ii) 10 to 70 weight percent of a styrene-type compound polymer having a number average molecular weight in the range from 50,000 to 200,000; is rendered fire retardant by the addition of an effective amount of a phosphine oxide having the formula:
wherein R, may be the same or different radicals selected from the group consisting of hydrogen and the methyl radical, R2 is an alkyl radical of 4 to 8 carbon atoms and n is either zero or one.