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 ofย flexibleย polyurethaneย that was flame retarded with melamine was compared with that of flame retarded with t ri ammon ium orthophosphate .
- The reductionย ofย ย theย flammability of the flexible polyurethane foams was
- The extent of the effects of the two flame retardants on the ignition behaviour of flexibleย polyurethaneย 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,ย gasoline) orย polymeric materials (plastic, cellulose) and oxygen. In order to produce fire a combustible materials and oxygen must be present and in contactย 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 spaceย [10]. Fire is a common term for combustion especially when out of control combustion refers to exothermic reaction inย any phase.ย It usuallyย ย ย ย ย ย implies propagation and oxidation.ย Inย mostย combustionย processes the exothermic stages occur in the gasย phaseย regardlessย of theย initialย phasesย ofย the ย reactants. ย Therefore , flames are associated with most combustionย ย ย ย ย processes. The combustibilityย ofย aย ย substanceย ย dependsย onย ย itsย chemical compositionย and physical stateย ย ย ย [3,10] . For instance, if the source of oxygen is air, then the molecules of any flammable gasย escapingย intoย theย air,ย will mix withย ย oxygen molecules and at ignition temperature,ย willย burn.ย Inย caseย ofย aย liquid, the flammable liquid must first be vapourized and its vapour mixed with oxygen, and it will burn. Similarly, solids must usually be liquefiedย andย vapourized,ย orย at lease reduced to small particles, with large surface area before it will burn.
Everyย ย materialย mustย beย ย raisedย ย toย ย itsย ย ย specific ignition temperature before a fire will occur, though oxidation of the material may take place below this temperature. Oxidation normallyย involve s atmosphericย ย ย ย ย ย ย ย ย ย oxygen,ย ย ย but manyย 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 andย raisesย the next area of unburned fuel to ignition temperature. Normally the ignition temperature of solids are higher thanย 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 โ 6) above were all obtained from Marthar foams industries Ltd., Nkpor โ 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 muffleย furnace,ย AAFย 11/ 18 serial No: 20โ 501901
Methods
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Polyurethane foam formulations
Martharย foams industries formulaย for foam production was used forย the foam recipe. The quantity of raw materials used in the production of polyurethane foam wereย constant,ย only the concentrationย of flame retardants were varied.
CHAPTER FOUR
RESULTS AND DISCUSSION
After Glow Time (AGT)
The resultsย of theย after glow time produced with the twoย flameย retardants ย are ย shownย inย ย Table 6, 3 below . The incorporation of ย these twoย ย flame retardants into theย substrate substantially reduced AGT โ as much as six โ 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 availableย ย [47]. Thus, the higher the char, the longer the AGT values. ย In theย 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 ย when after the flame ย have ย been dowsed and everybody gone home, and the fire starting all over later. This scenario is because ; theย ย usually not perceptible glow wasย notย extinguished. Of causeย , the longer theย AGT time, the higher the risk ofย 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 ย and tri ammonium orthophosphate ,ย were successfullyย incorporated in the production of flexible polyurethane foams under the productionย conditions of a commercial foam industry.
Hence, itย isย clearย that the two flame retardants are ย suitable for producing commercial foams that are affordable and maintains the quality.
The two flame retardants are effective inย reducing the after – glow time (AGT), flame duration time and propagation rate properties . The reduction of these fire char5acterisitcis is paramountย to reductionย ofย 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,ย melamine showed better impact for after-glow time and flame duration time, while triammoniumorthophosphate is preferredย forย reductionย ofย ignitionย time andย propagation rate due to ย 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 becauseย of ย its ย availability and low
REFERENCES
- National Fire Protection Association (2008) fire loss in US duringย 2005,ย ย abridg edย ย reportย ( 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 โ 372.
- N. Eboatu (1992) Fire, Flammabilityย and Fire Fighting . Anchor Ednal Press, ย Lagos, p.25
- Nguyen ย Huyย (2008)ย โFlame Reta rdantsโ Microsoft Studentย (DVD), Redmond: WA: Microsoft Corporation 2007
- Gum;ย W. ย Riese; and H. Ulrich, (1992), Reaction Polymers; Oxford University Press , New York, pp . 108 – 112.
- Ulrich (1996) Chemistryย and Technology of Isocyanates;ย John Wiley &ย Sons ICN, New York, pp. 98โ 100.