WEB EXCLUSIVE: FRX Polymers, Inc., Chelmsford, Mass., is commercializing its inherently flame-retardant polyphosphonate, a new thermoplastic made by a polycondensation process similar to that used for polycarbonate. FRX started up its semi-works plant in July in Switzerland. Its first commercial uses are in conductive FR plastics, FR fibers, and thin, clear FR components.
As previously reported
, FRX polyphosphonate is clear like PC, but too brittle to be used on its own. FRX offers homopolymer for blending and copolymers with PC. The copolymer has an LOI of 40 and meets UL 94V-0 at 0.75 mm, vs. a minimum of 1.5 mm for PC alone. Toughness is said to be comparable to PC. When the copolymer is used in an alloy with ABS, it meets 94V-0 at 1.5 mm and has 30° C/54° F higher HDT than PC/ABS, along with improved toughness and hydrolytic stability. Polyphosphonate also blends well with PBT, causing no bloom or plateout, according to FRX. The benefits are said to include high flow, improved GWIT and CTI ratings, 94V-0 at 0.8 mm, and better toughness. In addition, a low-molecular-weight oligomer of polyphosphonate can be reacted with epoxy (it acts as a hardener) or unsaturated polyester to add flame retardance while retaining transparency. The oligomer is also miscible with TPU and the blend remains clear. FRX hopes to develop oligomers for reacting into thermoset polyurethanes.