Ignition-resistant additives

Impact polystyrene with ignition-resistant additives is used for appliance housings, such as those for television and small appliances. Structural foam impact polystyrene modified with flame-retardant additives is used for business machine housings and m furniture because of its decorability and ease of processing. Consumer electronics, such as cassettes, reels, and housings, is a fast growing area for use of polystyrenes. Medical applicatiuns include sample collectors, petri dishes, and test lubes. 

A signal that the amount of vacuum is appropriate is if the cut surface of the pellet appears dense and not foamy. In some cases, the ignition resistant additives may cause the pellets to appear foamy regardless of the level of vacuum. Too much vacuum can cause small pieces of melt, oils, and/or wax to be removed from the melt and condensed in the vacuum line. 

Unlike spark-induced combustion engines requiring fuel that resists autoignition, diesel engines require motor fuels, for vhich the reference compound is cetane, that are capable of auto-igniting easily. Additives improving the cetane number will promote the oxidation of paraffins. The only compound used is ethyl-2-hexyl nitrate. 

An example of a direct comparison of performance properties with and without added flame retardants for "New ignition resistant polycarbonate resins" is provided in a paper by workers at the Dow Chemical Company (32). The technology of the flame retardant additives is de scribed as including... 

Total additive loadings rarely exceed 1% of the finished resin. The criteria for ignition resistance are based on oxygen index and UL-94 ratings. The mode of action of the flame retardants is reported to be consistent with that of aromatic sulfonates as proposed by Webb (27). 

Although the ignition resistance of upholstered furniture, mattresses and bed assemblies are specified by tests on the final composite specimen, filling materials and foams are additionally required to conform to the 1988 regulations (Table IX). 

The effect of the addition of several aromatic amines on the surface-ignition resistance of an aviation gasoline has been determined by Male o6) 2% by weight of each of six... 

Special grades of polystyrene include impact polystyrene modified with ignition-resistant chemical additives. These were developed because of increased emphasis on product safety and used in many electrical and electronic appliances. The addition of flame-retardant chemicals docs not make the polymer noncombustible, but increases its resistance to ignition and decreases the rate of burning when exposed to a minor fire source. 

This term is used for any additives that allow a polymer to retard a flame, or for any polymer that shows the ability to slow fire growth when ignited. It does not mean noncombustible or ignition resistant—these are very different terms and should not be used to describe a flame-retardant material. A material that is truly noncombustible or ignition resistant either cannot be combusted (no thermo-oxidative decomposition can occur) or cannot be ignited with a particular size... 

Cresol Epoxy Novolac (CEN) and the epoxy derivative of tetrabromo-bisphenol-A (TBBA) are the resins typically employed to encapsulate microelectronic devices in molding compounds. The brominated resin, which is utilized as a flame-retardant additive to impart a degree of ignition resistance to the encapsulant, contains many unstable hydrolyzable bromides. These bromides, along with the presence of chloride impurities, are detrimental to the life of the electronic component. Specifically, bromine has been suspected and proven to cause wire bond failure (1-31. 

ABS/PC blends can be made flame retardant (UL flammability rating of V-0 at 1.6 mm) for use in the business electronics market without the use of chlorine or bromine additives or loss of processing window. Deflection temperatures can be maintained at 91-102°C under 1.82 MPa load. PC/ABS blends used for the housing for palm-pad computer are weatherable and ignition-resistant. 

Ignition-Resistant Chemical Additives See Flame Retardant. 

Inherent ignition resistance without the use of phosphorous or halogen additives... 

A potential area of application in which poly-PMS can give a significant Improvement In cost and performance Is flame retar-dance (FR) or Ignition resistance. PMS-based Impact resins require lower loadings of costly and heavy conventional FR additives to... 

Some of the tests and criterion used to define fire resistance may be found in the Hterature (9). Additionally, the compression—ignition and hot manifold tests as defined in MIL-H-19457 and MIL-H-5606, respectively the Wick test as defined by Federal Standards 791, Method 352 flash point and fire point as defined in ASTM D92 autoignition temperature as defined in ASTM D2155 and linear flame propagation rate are defined in ASTM D5306 are used. 

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