Ammonium Polyphosphate APP

Although not strictly a filler, this additive deserves a brief mention. Its mode of action is predominately by the promotion of char formation, resulting from high acidity phosphoric acids produced on pyrolysis. The polyphosphate is used, as it is less water soluble and hygroscopic than the orthophosphate. APP is effective on its own in polymers with suitable chemistry for char formation to occur by this mechanism. In other polymers, it is used in conjunction with a charring agent, such as a melamine derivative [58]. 

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Those based on the reaction between magnesium oxide and ammonium polyphosphate (APP) (Sugama Kukacka, 1983b). 

Sugama Kukacka (1983b) described cements based on magnesium oxide and a 56% aqueous solution of ammonium polyphosphate (APP). The po wder was a fine magnesium oxide that had been calcined above 1300 °C and had a surface area of 1 to 5 m g . The reaction was strongly exothermic the cements set within 3 minutes and developed an early strength of 13-8 MPa after 1 hour and over 20 MPa after 5 hours. 

Recently, some reports have explored the potential of synergistic effect between silica and other flame retardants.53-55 For example, silica showed synergistic effect with alumina in polypropylene (PP)/ammonium polyphosphate (APP)—pentaerythritol (PER) intumescent-based system. The data indicate that the HRR values improved by incorporating silica into the intumescent-based formulation and the improvement was much more pronounced by combining both silica and alumina in the formulation. 

Interestingly enough, Schmittman et al. claimed that a combination of ammonium polyphosphate (APP), ammonium phosphate, borax, anhydrous borax (<45 pm), and melamine can be used in urethane panels to meet the German standard DIN 4102, Part 1, point 6.1.2. (B1 classification).13 They specifically reported that the combination of borax and anhydrous borax yields surprisingly effective results. 

In numerous works dealing with the combination of nanoparticles and FR compounds, surface modifications of nanoparticles were only aimed to promote good dispersion of the nanoparticles into the polymer matrix (with intercalated or exfoliated morphologies for layered silicates as nanoparticles), even in the presence of the usual FRs, for example ammonium polyphosphate (APP) or magnesium hydroxide (MH). The initial aim was to combine the individual effects of each component to achieve strong synergistic effects. 

Member Compositional Matrix of Polystyrene (PS) Containing Various Levels of a 3 1 Mass Ratio of Ammonium Polyphosphate (APP/PER (3 1)) or a Cloisite 15A Organoclay... 

Cotton Ammonium phosphates are the most effective FRs for cotton as first identified by Gay-Lussac in 1821 and still widely used. All phosphates on heating release phosphoric acid, which catalyses dehydration reactions of cellulose to yield char at the expense of volatiles formation reactions.50 However, ammonium phosphates like mono- or diammonium phosphates are water soluble, hence applicable as nondurable treatments only. Ammonium bromide can be used in combination with ammonium phosphates to provide some vapor-phase FR action. Other examples include borax and boric acid, ammonium sulfamate, and sulfates. These nondurable finishes are useful for disposable fabrics, insulation, wall boards, theatrical scenery, packaging material, paper, etc. Ammonium polyphosphates (APPs) are used in combination with urea to provide semidurable finishes and by curing at 160°C, when some phosphorylation can occur. Semidurable finishes are very useful for materials that may not need frequent washings, e.g., mattresses, drapes, upholstery, carpets, etc. Some commercial examples of semidurable finishes include Flammentin FMB (Thor Specialities), Pyrovatim PBS (Ciba, now marketed by Huntsman), etc.26... 

Liquid ammonium phosphate fertilizers ammonium polyphosphate (APP)... 

Ammonium polyphosphate (APP) leads to the formation of a char layer through the linking of phosphates to the ester group the latter are readily eliminated forming conjugated double bonds, which finally cyclise to give a char [18]. 

The German Federal Environmental Agency defined P-red use as unproblematic (like ammonium polyphosphate (APP) and ATH) in its risk assessment report on the most commercially important FRsin August 2001. 

ATH) and magnesium hydroxide (MOH) as well as materials such as melamine and derivatives, ammonium polyphosphates (APPs), antimony oxide, and boron-containing materials such as zinc borate and others. 

Another application of compatibilisers is in intumescent formulations for PP compositions used in vehicles, where better flame retardancy is being sought for various reasons. The intumescent mixtiue sometimes incorporates a polyamide as the carbonisation polymer, together with ammonium polyphosphate (APP) to improve the fire performance. PA and APP have limited compatibility, and EVA can overcome this. Attempts have been made to demonstrate that such mixtmes can count towards the 80% of recyclable vehicle weight demanded by the EU Directive relating to end-of-vehicle life issues. 

Phosphorus and phosphates, notably ammonium polyphosphate (APP), are an example of the first effect. Nano-clays also appear to enhance char properties, although the mechanisms are not fully understood at present. 

In their search for incandescence inhibitors, they screened a number of known organic catalyst poisons but without success, probably due to insufficient thermal stability. Inorganic additives proved more promising. Ammonium polyphosphate (APP) was found to be very effective but suffers from water sensitivity problems and was rejected on this basis. Surprisingly antimony trioxide, which is often regarded as an incandescence promoter itself, was found to be very effective and was their preferred material. Unfortunately, the effectiveness of antimony trioxide on flame retardancy and smoke formation was not reported on. 

Intumescent systems are usually based on ammonium or amine phosphates, of which ammonium polyphosphate (APP) has received the most attention, followed by melamine phosphate (MP) and ethylenediamine phosphate (EDAP). Other related materials which have been reported or used in mechanistic studies are melamine amyl phosphate and diammonium pyrophosphate. 

FIGURE 11.9 Percentage residual mass differences between resin-flame-retardant clay and respective resin-flame-retardant TGA responses to show the effect of Cloisite 25A clay on the thermal degradation of a vinyl ester resin containing the flame retardants ammonium polyphosphate (APP), melamine phosphate (NH), melamine phosphate and dipentaerythritol (NW), and alumina trihydrate (ATH). (From Ref. 13, with permission from the Royal Society of Chemistry.)... 

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