Intumescence ingredients

Industrial furnace tests, according to UL-1709 standard, have been carried out in a 1.5 m3 furnace (Figure 6.20) for further comparison with the heat radiator test. Different intumescent formulations have been examined The first type comprised three basic intumescent (ingredients include APP, PER, and melamine) epoxy resins (IF1, IF2, and IF3) whose performance is compared to a reference commercial intumescent epoxy resin (IF4). 

Carbonaceous char barriers may be formed by the normal mode of polymer burning, and besides representing a reduction in the amount of material burned, the char may act as a fire barrier. The relationship of char yield, structure, and flame resistance was quantified by Van Krevelen (5) some years ago. For polymers with low char-forming tendencies, such as polyolefins, one approach to obtain adequate char is to add a char-forming additive. Such additives generally bear a resemblance to intumescent coating ingredients (6, 7). 

The quick overview of the mechanisms of action reveals that the formation of an expanded charred insulative layer acting as thermal shield is involved. The mechanism of action is not completely elucidated, especially the role of the synergist. Reaction may take place between the nano-filler and some ingredients of the intumescent formulation (e.g., the phosphate) in order to thermally stabilize the charred structure. Only physical interactions are observed (e.g., action of POSS with phosphinate), and these interactions permit the reinforcement of the char strength and avoid the formation of cracks. The development rate and the quality of this layer are therefore of the primary importance and research work should be focused on this. 

Ingredients used in intumescent systems usually fulfill more than one function. Most compounds release some gas on heating, therefore they can be considered to be blowing agents. Many compounds produce some char. 

Diethyiene glycol diacrylate 2,2, 4,4, 5,5 -Hexachlorobiphenyl Isophthalic acld/trimethylolethane/soybean oil polymer paint ingredient, intumescent Ammonium polyphosphate Dicyandiamide ... 

Dimelamine phosphate Melamine phosphate paint ingredient, intumescent fire-retardant Melamine paint lacquers 2-Ethyl hexanol paint mfg. 

Amgard lU Albright and Ammonium-poly- 55% P,0. white powder. ingredient of intumescent... 

Intumescent flame retardants (IFR) that contains phosphorus are also used in halogen-free flame-retardant systems. Most reported IFRs are mixtures of the three ingredients, an acid source, a polyol, and a nitrogen-containing compound (Halpem et al. 1984). Since processing of ABS resin requires that the additives withstand temperatures in excess of 200 °C, the commonly used intumescent system, ammonium polyphosphate, pentaerythritol, and melamine, which do not have sufficient thermal stability, cannot be incorporated into ABS resin under normal processing conditions they are usually used in polyolefins. 

Nitrogen-containing FRs (without any phosphorus compounds) hold only a small share of the global FR market at present, although their popularity is growing. The main active ingredients are usually melamine cyanurate and melamine hydrobromide, although melamine phosphate is used in intumescent FR systems in combination with pentaerythritol. Melamine based flame retardants employ several modes of flame retardant action. 

Zeolite does not need to be a true catalyst, because it reacts (zeolite is a crucial reactant of the intumescent reaction) with the other ingredients of the intumescent formulation (reaction of phosphate with the aluminosilicate). The latter reaction permits the formation (in situ and in the conditions of fire) of species that stabilize the intumescent structure. So it can be expected that the use of species such as aluminosilicate, able to react with phosphate, should also provide enhanced flammability properties. 

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