Flame-retarded grades

The market prices for PET molding resins in January 1996 in the United States were 2.90— 3.15/kg for 30% glass-filled PET, 3.26— 3.41/kg for 55% glass-filled, and 3.23— 3.45/kg for 30% glass-filled flame-retardant-grade PET (125). 

Table 6. Properties of Flame-Retardant Grades (THERMX PCT) ...

DMPPO—polystyrene blends, because of the inherent flame resistance of the DMPPO component (oxygen index ca 29.5), can be made flame retardant without the use of halogenated additives that tend to lower impact strength and melt stabiUty in other polymers. Approximately one-half of total Noryl sales volume is in flame-retarded grades, ie, VO or VI in a 1.6-mm section (UL-94). 

Pellets for injection-molding, extmsion, and blow-molding appHcations include mineral-filled, glass-filled, pigmented, and flame-retarded grades. 

Blends of ABS with polycarbonates have been available for several years (e.g. Bayblend by Bayer and Cycoloy by Borg-Wamer). In many respects these polymers have properties intermediate to the parent plastics materials with heat distortion temperatures up to 130°C. They also show good impact strength, particularly at low temperatures. Self-extinguishing and flame retarding grades have been made available. The materials thus provide possible alternatives to modified poly(phenylene oxides) of the Noryl type described in Chapter 21. (See also sections 16.16 and 20.8.)... 

Flame retardant grades usually employ additives (but see below), e.g. sodium 2,4,5-trichlorobenzene sulphonate, sometimes in conjunction with an antidripping agent which, it is claimed, cross-links the polymer as it bums thus reducing the tendency to drip. 

Flame retardant grades may not only use additives such as sodium 2,4,5-trichlorobenzene sulphonate but also an anti-dripping agent which can cause cross-linking as the polymer bums, thus reducing the tendency to drip. 

More to be expected of a more hydrocarbon polymer than PET is a somewhat lower water absorption, typically about 70% that of PET. With appropriate flame retardants, grades can have a UL V-0 rating at 0.8 mm thickness. 

Fire safety Flame-retardant grade. Class P not easily ignitable to BS 476 Part 5. 

Flame-retarded grades are widely used for various computer connectors and circuit board components. Representative applications are edge card connectors, grid arrays and memory modules. Non-flame-retarded grades find use in automotive under-the-hood applications, typically connectors and related parts. As higher temperature soldering techniques become more common in the automotive industry, the use of high-temperature plastics such as PCT is expected to increase. It is also possible to formulate unreinforced PCT with crystallization aids and... 

Table 3.15 Examples of flame-retardant grade properties...

The development of the different methods for the production of flame retardant grade magnesium hydroxide has recently been reviewed [100]. Although not a common mineral, there are some workable deposits of brucite, especially in the US and China and product obtained by milling high purity brucite deposits is being marketed, but has so far made little impact. This is probably because the high levels needed for flame retardancy can only be tolerated if the particle size and shape are carefully controlled and this requires the use of synthetic methods of production. 

Description The BP/Lummus styrene polymerization technology for the manufacture of regular and flame-retardant grades of EPS is a one-step batch suspension reaction followed by continuous dewatering, drying and size classification. 

To develop flame retarded grades [56-58]. A lot of work has been carried out using ASA-polycarbonate blends. However, this field will not be covered here. 

In just 17 years, the entire field of flame retardancy has taken a giant leap forward and the technology to provide FR synthetic materials has made remarkable progress. Today, flame retardant grades of synthetic polymers have found applications in areas considered impossible a few years ago. One example is the use of polyurethane foam in upholstered furniture for high-risk occupancies such as hotels, prisons and hospitals. Polyurethane foam, which was once described in the press as "solid gasoline" is now formulated to withstand severe fire test exposure without propagating the fire. 

Figure 11.1 Electon micrograph of Kisuma 5J flame-retardant-grade magnesium hydroxide.

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