Flame retardancy of polycarbonate enhanced by adding fly ash.

We have developed a flame‐retardant polycarbonate resin whose flame retardancy is greatly enhanced by adding fly ash (a by‐product from thermal power plants). Fly ash with comparatively small average particle sizes (<10 µm) raised the flame retardancy of polycarbonate because of the hydrogen bond that forms between the polycarbonate and the hydroxy group on the fly ash surface. This bond primarily improves the heat resistance of the polycarbonate and also isomerizes the polycarbonate to promote carbonization. The polycarbonate with 25 wt% of the fly ash showed good other main characteristics, such as mechanical properties and moldability, comparable to those of a flame retardant polycarbonate reinforced with glass fiber, used for electronic products such as desktop computers, etc. Applying the fly ash eliminates the need to use current retardants such as organic halogen compounds and thus promotes the perceived environmental safety of flame‐ retardant polycarbonate. In addition, being able to use less raw resin by adding the fly ash means that less energy is required to manufacture flame‐retardant polycarbonate. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]