Fire retardancy flame-retarded matrices

Ammonia—Gas-Cured Flame Retardants. The first flame-retardant process based on curing with ammonia gas, ie, THPC—amide—NH, consisted of padding cotton with a solution containing THPC, TMM, and urea. The fabric was dried and then cured with either gaseous ammonia or ammonium hydroxide (96). There was Httle or no reaction with cellulose. A very stable polymer was deposited in situ in the cellulose matrix. Because the fire-retardant finish did not actually react with the cellulose matrix, there was generally Httle loss in fabric strength. However, the finish was very effective and quite durable to laundering. 

The surface area and degree of dispersion in the polymer matrix of the fire-retardant additive has a pronounced effect on its efficiency. Colloidal tin(IV) oxide is significantly more effective, in terms of its flame-retardant ability, than powdered tin(IV) oxide or B-stannic acid. 

Figure 6.10 depicts the morphology of POCs reinforced with date palm fiber (DPF) and Mg(OH)2 added as flame retardant. The SEM micrograph shows the stmcrnre of (a) pure MgOH flame retardant as filler, (b) natural fiber as a reinforcement material in PO matrix, and (c) distribution of MgOH in PO matrix. Figure 6.11 shows the use of POCs with fire retardant filler. 

Bromination of vinyl-ester resin imparts fire retardancy as manifested by flame spread and lower RHR [50]. However, this fire-retardant system functions primarily in the gas phase causing incomplete combustion. As such, brominated resins produce dense smoke, and an increase in the yield of CO and HBr. Recent interest in the use of non-halogenated organic-matrix composite materials in US Navy submarines and ships has generated the requirement for significant improvement in the flammability performance of these materials including reduction in the amount of smoke, CO and corrosive combustion products. 

Materials with highly cross-linked epoxy resin reinforced with woven fiber glass are the most common in use. Bromine is reacted with the epoxy matrix and is used to provide fire retar-dancy. Most epoxy-based materials satisfy the Underwriters Laboratories (UL) classification of V-0 for fire retardancy. The generic term for this family of epoxy resin materials is FR-4, with FR standing for flame retardant and 4 an assigned number indicating epoxy. Epoxyfiberglass materials are sold by many snpphers and have become a commodity material. 

The matrix resin should have excellent comprehensive properties, including mechanical, electrical, thermal performance, chemical resistance, anti-aging, flame retardancy and so on. However, it is impossible for an Individual matrix resin to have all the properties simultaneously, so the appropriate one should be chosen according to usage requirements and characteristics of packing materials. For example, fire retardancy, compatibility of filler and matrix resin, and dispersibility of filler in the resin should be taken into account to make the filled composite material meet usage requirements. 

Polypropylene nanocomposites have attracted more and more interest in flame retardant area in recent years due to their improved fire properties [18-20], It is suggested that the presence of clay can enhance the char formation providing a transient protective barrier and hence slowing down the degradation of the matrix [19,20],... 

Phosphorus is the most flame-retardant element known typically 5 wt.% P in PP can provide fire-proofing properties. Organic or mineral phosphorus may be used as flame retardant but generally the performance even at high loading (> 30 wt.%) remains poor and the weak compatibility between the additives and the polymeric matrix leads to a strong decrease of the mechanical properties of PP. 

Phenolic composites have been the material of choice when fire safety is the main criterion for the selection of building materials. Due to the intrinsic properties of the matrix, phenolic composites do not support a flame, and when exposed to fire they produce little or no smoke, which is less toxic than the smoke produced by other composites, particularly those containing certain halogenated flame retardants (Johanson, 2005). 

The accumulation of clay at the surface acts thus as a barrier which limits heat transfers and reduces the release of combustible volatiles into the flame. A substantial decrease in the peak heat release rate of the nanocomposite (25 to 50%) can be achieved compared to the neat polymer (Bourbigot et al, 2006). However, this effect is very dependent on the quality of dispersion of the nanoparticles within the host matrix, and a high degree of exfoliation is usually targeted in order to maximize both the mechanical and fire properties (Hackman and Hollaway, 2006). Other types of nanoparticles, such as silica (Si02), titanium dioxide (Ti02), carbon nanotubes or silesquioxane, have also proven to have significant flame-retardant properties (Laoutid et al., 2009). 

Two component, pre-catalyzed, flame retardant, low smoke/low toxicity (High LC50, U-PITT test), phenol resorcinol matrix resins. Three grades are available, 1000FM, 1030FM and 1060FM of different viscosity and solids content. Aii three systems are listed by Factory Mutual as "Identified Components for the Manufacture of Fire or Smoke Exhaust Ducts . 

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