Investigation of Effects of Two Flame Retardants on the Fire Characterisitics of Flexible Poly Ether Foam
CHAPTER ONE
The objectives of the Study;
- The effects of melamine and tri ammoniumorthophosphate on the fire characteristics of the flexible polyurethane foams were
- The fire characteristics of flexible polyurethane that was flame retarded with melamine was compared with that of flame retarded with t ri ammon ium orthophosphate .
- The reduction of the flammability of the flexible polyurethane foams was
- The extent of the effects of the two flame retardants on the ignition behaviour of flexible polyurethane foams was established .
CHAPTER TWO
LITERATURE REVIEW
Fire, Pyrolyses and Combustion
Fire is the reaction involving fuel and oxygen that produces heat and light . It results from rapid chemical reaction between a fuel (wood, gasoline) or polymeric materials (plastic, cellulose) and oxygen. In order to produce fire a combustible materials and oxygen must be present and in contact at sufficient high temperature to initiate combustion. Th e two substances (oxygen and fuel) must continue to be in contact for combustion to be sustained.
A flame is a gas phase combustion reaction which is able to propagate through space [10]. Fire is a common term for combustion especially when out of control combustion refers to exothermic reaction in any phase. It usually implies propagation and oxidation. In most combustion processes the exothermic stages occur in the gas phase regardless of the initial phases of the reactants. Therefore , flames are associated with most combustion processes. The combustibility of a substance depends on its chemical composition and physical state [3,10] . For instance, if the source of oxygen is air, then the molecules of any flammable gas escaping into the air, will mix with oxygen molecules and at ignition temperature, will burn. In case of a liquid, the flammable liquid must first be vapourized and its vapour mixed with oxygen, and it will burn. Similarly, solids must usually be liquefied and vapourized, or at lease reduced to small particles, with large surface area before it will burn.
Every material must be raised to its specific ignition temperature before a fire will occur, though oxidation of the material may take place below this temperature. Oxidation normally involve s atmospheric oxygen, but many other oxidizers produce flames and some flames do not involves oxidation reactions. Above the ignition temperature, the heat of oxidation does not dissipate fast enough and raises the next area of unburned fuel to ignition temperature. Normally the ignition temperature of solids are higher than those of the liquids.
When a part of any material is exposed to external source of heat, its temperature will rise as a result of heat transfer. As temperature progressively increases, a point is reached when enough thermal energy has been imbibed as to break bonds.
CHAPTER THREE
EXPERIMENTAL
Materials and Methods
The materials include:
- Polyol
- Toluenediisocynate (TDI)
- Silicone
- Dimethylethanol amine
- Water
- Stanousoctate or Tin II
- Melamine
- Tri ammonium orthophosphate
Material (1 – 6) above were all obtained from Marthar foams industries Ltd., Nkpor – Obosi Road, Onitsha Anambra State Nigeria.
Melamine and tri ammonium orthophosphate were bought from Laboratory of National Research Institute for Chemical Technology (NARICT), Zaria .
Apparatus
Apparatus used for the experiment are:
- Carbolite muffle furnace, AAF 11/ 18 serial No: 20– 501901
Methods
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Polyurethane foam formulations
Marthar foams industries formula for foam production was used for the foam recipe. The quantity of raw materials used in the production of polyurethane foam were constant, only the concentration of flame retardants were varied.
CHAPTER FOUR
RESULTS AND DISCUSSION
After Glow Time (AGT)
The results of the after glow time produced with the two flame retardants are shown in Table 6, 3 below . The incorporation of these two flame retardants into the substrate substantially reduced AGT – as much as six – fold at 2.5pph melamine concentration. Glow is an exothermal oxidative combustion of material without a flame and is known to depend on quantity of carbonaceous char available [47]. Thus, the higher the char, the longer the AGT values. In the Fig. 3 below, at all concentrations after glow is decreased with respect to untreated sample. The significance of this observation becomes clear if it is realized that in fire situation, what is most striking is the flame and that attracts fire combatants. There have been countless cases when after the flame have been dowsed and everybody gone home, and the fire starting all over later. This scenario is because ; the usually not perceptible glow was not extinguished. Of cause , the longer the AGT time, the higher the risk of re-enlightenment of a fire. Obviously therefore, reduction of AGT is a very useful technique in fire chemistry.
CHAPTER FIVE
CONCLUSION
The following conclusion can be made from the results of the study.
The two flame retardants, melamine and tri ammonium orthophosphate , were successfully incorporated in the production of flexible polyurethane foams under the production conditions of a commercial foam industry.
Hence, it is clear that the two flame retardants are suitable for producing commercial foams that are affordable and maintains the quality.
The two flame retardants are effective in reducing the after – glow time (AGT), flame duration time and propagation rate properties . The reduction of these fire char5acterisitcis is paramount to reduction of flammability of the polyurethane foam which leads to safety of lives and properties.
Dramatic increase in ignition time and charring percentage shown by t ri ammonium orthophosphate is evidence that its incorporation into polyurethane will delay burning on occasions of fire, t hereby increases time for safety of life and properties.
However, melamine showed better impact for after-glow time and flame duration time, while triammoniumorthophosphate is preferred for reduction of ignition time and propagation rate due to increase in high percentage charring.
RECOMMENDATION
- The two flame retardants are recommended for use for retarding commercial polyurethane foams, that will reduce the incident of fire and destruction of life and
- Tri ammonium ortho phosphate is preferred for retarding flexible polyurethane foams to
- The commercial foam industries that are not incorporating any flame retardants to their products, because of cost, can now start to make use of these two flame retardants because of its availability and low
REFERENCES
- National Fire Protection Association (2008) fire loss in US during 2005, abridg ed report ( http:/ / usfa. gov/ statistic / National) ( Retrieved, February 28, 2010)
- M. Avento, (1980), Flame Retardant , an Overview. Encyclop aedia of Chemical Technology Vol. 10, John Wiley & Sons. New York , pp 348 – 372.
- N. Eboatu (1992) Fire, Flammability and Fire Fighting . Anchor Ednal Press, Lagos, p.25
- Nguyen Huy (2008) “Flame Reta rdants” Microsoft Student (DVD), Redmond: WA: Microsoft Corporation 2007
- Gum; W. Riese; and H. Ulrich, (1992), Reaction Polymers; Oxford University Press , New York, pp . 108 – 112.
- Ulrich (1996) Chemistry and Technology of Isocyanates; John Wiley & Sons ICN, New York, pp. 98– 100.
