Flame retardant polycarbonate compositions, methods of manufacture, and articles formed therefrom

A composition comprising:

• a first polycarbonate comprising a poly(siloxane-carbonate) derived from at least one dihydroxy aromatic containing polycarbonate unit, and at least one polysiloxane bisphenol of formula (1), formula (2), or a combination thereof
• wherein
• R is each independently a C1-C30 hydrocarbon group,
• R2 is each independently a C7-C30 hydrocarbon group,
• Ar is each independently a C6-C30 aromatic group and
• E has an average value of 5 to 200;
• a bromine-containing compound different from the first polycarbonate, wherein the bromine-containing compound is a second polycarbonate comprising
• brominated carbonate units derived from 2,2′,6,6′-tetrabromo-4,4′-isopropylidenediphenol and
• carbonate units derived from at least one dihydroxy aromatic compound that is not 2,2′,6,6′-tetrabromo-4,4′-isopropylidenediphenol;
• or
• a brominated oligomer having a weight average molecular weight of less than 18,000 Daltons as measured by gel permeation chromatography using polystyrene standards;
• and
• optionally, a third polycarbonate different from the first polycarbonate and the bromine-containing compound, the third polycarbonate comprising carbonate units and ester units;
• wherein
• the wt % of the first polycarbonate, the bromine-containing compound, and the optional third polycarbonate sum to 100 wt %,
• the first polycarbonate is present in an amount effective to provide the siloxane units in an amount of at least 0.3 wt %, based on the sum of the wt % of the first polycarbonate, the bromine-containing compound, and the optional third polycarbonate, and
• the bromine-containing compound is present in an amount effective to provide the bromine of the bromine-containing compound in an amount of at least 7.8 wt %, based on the sum of the wt % of the first polycarbonate, the bromine-containing compound, and the optional third polycarbonate;
• and
• further wherein if present, the optional third polycarbonate is present in an amount
• such that an article molded from the composition has
• an OSU integrated 2 minute heat release test value of less than 65 kW-min/m2 and a peak heat release rate of less than 65 kW/m2 as measured using the method of FAR F25.4, in accordance with Federal Aviation Regulation FAR 25.853 (d), and
• an E662 smoke test Dmax value of less than 200 when measured at a thickness of 1.6 mm.