Nonhalogenated fire retardant materials

WEEE has had a direct affect on flame-retardant use, because flame retardants are used in almost all electrical and electronic equipment to prevent fires from short circuits. This directive lays down rules for disposal and recycling of all electrical and electronic equipment that goes back to the previous incinerator discussion. For flame retardants, this directive affects how the plastic parts, cable jackets, and enclosures are flame retarded. If the plastic cannot be reground and recycled, it must go to the incinerator, in which case it cannot form toxic by-products during incineration. This has led to the rapid deselection of brominated FR additives in European plastics that are used in electronics, or the complete removal of FR additives from plastics used in electronics in Europe. This led, in turn, to increases in electrical fires in Europe, and now customers and fire-safety experts demand low environmental impact and fire safety. However, the existing nonhalogen flame-retardant solutions brought in to replace bromine have their own balance-of-property issues, and so research continues to develop materials that can meet WEEE objectives. 

FIGURE 8.1 HRR for polycarbonate and polycarbonate-containing silicone (two repeated tests for each sample). (From Kashiwagi, T. et al., A nonhalogenated, flame retarded polycarbonate, in Conference of Advanced Fire Resistant Aircraft Interior Materials, Atlantic City, NJ, February 9-11, 1993, 175.)... 

To summarize, the field of flame retardancy for polymers is in a state of flux, and multiple new technologies and approaches are expected to arise in the coming decade. In this entry, we focus on some new technology from our laboratory, including nonhalogenated flame retardants synthesized from bromi-nated starting materials, and inherently fire-safe and low-flammability polymers. 

Halogen-based flame retardants have served a great need for effective flame retardancy for several years. Due to relatively recent environmental concerns, there is a continuing trend toward the development of nonhalogenated materials to replace these systems. While this has been underway for quite some time, it does not appear that nonhalogenated materials will be available in the near future. Hence it appears that there is still a need for these materials to prevent fires. 

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