INVESTIGATION OF EFFECTS OF TWO FLAME RETARDANTS ON THE FIRE CHARACTERISIT ICS OF FLEXIBLE POLY ETHER FOAM
Title page
Certification
Dedication
Acknowledgements
Abstract
Table of contents
List of table
List of figures
CHAPTER ONE INTRODUCTION
1.1 Background of the study
1.2 Significance of the Research.
1.3 Scope of the Study
1.4 The objectives of the Study;
CHAPTER TWO
2.1 Fire, Pyrol yses and Combustion
2.1.2 Pyrolysis of Plastics
2.1.3 Pyrolysis of Polyurethane foams
2.2 Flame Retardants
2.2.1 Historical development of flame retardant s.
2.2.2 Types of flame retardants
2.2.2.1 Inorganic flame retardants
2.2.2.1.1 Antimony Compounds
2.2.2.1.2 Boron Compounds
2.2.2.1.3 Other metal compounds
2.2.2.1.4 Phosphorus Compounds
2.2.2.2 Halogenated Organic Flame Retardants
2.2.2.2.1 Brominated flame retardants.
2.2.2.2.2 Chlorinated flame retardants
2.2.2.3 Organophosphorus Flame Retardants.
2.2.2.4 Halogenated phosphates
2.2.2.5 Nitrogen – based flame retardants
2.3 Mechanism of action of flame retardants
2.3.1 Physical action of flame retardants
2.3.2 Chemical reactions
2.3.2.1 Reaction in the gas phase:
2.3.2.2 Condensed phase mechani sms.
2.4 Some Suppressants
2.5 Melamine as a flame retardant
2.5.1 Synthesis of Melamine
2.5.2 Mechanism of reaction of melamine as flame retardants.
2.5.3 Applications and benefits of Melamine
2.5.4 Applications of melamine and its derivatives
2.5.5 Benefits of Melamine
2.6 Tri ammonium Orthophosphate as a Flame Retardants
2.6.1 Mechanism of Reaction of Tri ammonium orthophosphate as a flame retardant
2.7 Polyurethane as a foam polymer
2.7.1 History of Polyurethane Foams
2.7.2 Definition of Pol yurethane foams
2.7.3 Chemistry of Flexible Polyurethane Foam
2.7.4 Gelation (Polymerization) Reaction
2.7.5 Blow Reaction
2.7.6 Basic Components of Flexible Polyurethane Foam
2.7.6.1 Isocyanates
2.7.6.2 Polyols
2.7.6.3 Water
2.7.6.4 Physical Blowing Agents
2.7.6.5 Catalysts
2.7.6.6 Tertiary Amine Catalysts
2.7.6.7 Organometallic Catalysts
2.7.6.8 Surfactants
2.7.6.9 Cross – Linkage Agents
2.7.7.0 Other Additives
2.7.7.1 Morphology of the polyurethane foam
2.7.7.2 Cellular Structure of the polyurethane foam
2.7.7.3 Applications of polyurethane
CHAPTER THREE EXPERIMENTAL
3.1 Materials and Methods
3.1.1 Apparatus
3.2 Methods
3.2.1 Polyurethane foam formulations
3.3 Preparation of the foam samples for characterization
3.3.1 Flame characteristics
3.3.2 Determination of After glow time (AGT)
3.3.3 Determination of Ignition – time
3.3.4 Determination of Flame propagation
3.3.5 Determination of Flame duration
3.3.6 Determination of Percentage char formation
CHAPTER FOUR
RESULTS AND DISCUSSION
4.1 After Glow Time (AGT)
4.2 Ignition Time
4.3 Flame Propagation Rate
4.4 % Char Formation
4.5 Flame duration
4.6 Conclusion
4.7 Recommendations
References
Appendix
ABSTRACT
This work studied the effects of two flame retardants on the fire characteristics of flexible polyether foam samples. Various concentrations of two flame retardants melamine and tri ammonium orthophosphate have been successfully incorporated into flexible polyurethane foam. Results of the analyses carried out on the various foam samples showed that by appropriate incorporation of the two flame retardants, the flammability properties (After glow time (AGT), ignition time, flame duration time, flame propagation time and percentage char) have been greatly improved through both condensed (solid) phase and gas phase mechanisms specifically. The After glow time (AGT), flame duration time and propagation rate were greatly reduced, while the ignition time and percentage charring were increased with inc rease in concentration of the two flame retardants. However, melamine showed better impact for reduction of after glow time and flame duration time while tri ammonium orthophosphate is preferred for increase in ignition time and reduction in flame propagat ion rate with outstanding evidence of high percentage charring ability.
CHAPTER ONE
INTRODUCTION
1.1 Background
Fire is a world wild problem which c laims lives and causes significant loss of properties. Most of the immediate surroundings of man consist of polymeric materials which are combustible materials. These include clothes , furniture, construction materials, and interior decorations. Generally, the interiors of homes, offices, vehicles, and packages are decorated with foamed plastics. The constitution of foamable polymeric materials made them liable to easy ignition and vigorous burning under right conditions. Humans have always been plagued by unwanted fire, which usually gulfed life and properties worth of millions of naira.
In addition to immediate fire risk pose d by the polymeric materials while burning, their combustion products often cause serious threat to human health and environment . In United States between 1996 and 2005 it was reported that an average of 3,932 human loss and another 20,919 injuries were as a result of fire accidents [1].
Recently, on 9 th Oct 2009, along Enugu -Onitsha express road, over ten vehicles loaded full with humans and property worth millions of naira were engul fed by fire. Therefore, the need to seek efficient and af fordable ways of reducing the flammability of polymeric materials in our sur roundings is of primary importance.
A flame is a rapid free radical , chain reaction of volatile materials with oxygen in the air. It is actually the resultant flame or fire that consumes life and properties. The term fire retardant (flame retardant) descri bes materials that inhibit or resist flammability of polymers . In the same vein a fire retardant chemical is used to denote a compound or mixture of compounds that when added to, or incorporated chemically into polymers, serve to slow down or hinder the ignition or growth of fire [2]. In other words, a flame retardant chemical is therefore a compound or mixture of compounds which when added to or chemically incorporated into a polymeric material, substantially suppresses the ease of ignition and/or flame pr opagation [3].
The above definitions of flame retardant denote that it generally either lower ignition susceptibility or lower the flame propagation once the ignition has occurred. The products on which flame retardants can be applied include apparels, carpets, and rugs, construction materials (thermal) insulation foams, wall coverings and composites to meet governmental regulations for buildings, aircraft, auto mobiles. Flame retardants can be incorporated into a material either as a reactive component or as an additive component. As a reactive, such flame retardants are incorporated into the polymer structure of the plastics , example, when polyurethane and polyamides are retarded with red phosphorus .
Flame retardants are usually classified into three typ es: non durable, semi durable and durable finishes, based on durability, or fastness to (laundry) light, heat chemicals etc . [3].
i. Non- durable finishes. These are used for packaging materials, paper and furnishings. They include formulations containing , borax and other borates. Others are aliphatic amine phosphate (e.g. triethanolamine phosphate) , urea sulphamates, ammonium and diammonium phosphate, ammonium bromide and ammonium polyphosphate.
ii. Semi durable finishes . These include flame retardants for mattresses, drapes, upholstery and carpets which can withstand 1-20 washings in water , for example, precipitate of a mixture of oxides of tungsten and tin in the soluble salts.
iii. Durable finishes . These retardants are very durable and can import excellent antimony oxide with durable functions to cotton fabrics, for example chlorinated paraffin.
Most flame retardants contain elements from group III A, (boron and aluminum) group VA (nitrogen, phosphorus, arsenic and a ntimony) and group VII A (fluorin e, chlorine and bromine) [4].
Group III : A flame retardant which contain boron or aluminum work by forming char which acts as a protective layer that prevents oxygen from reaching the inner layers of the material and thus sustaining the fire. Chemicals commonly used for this purpose include borax, boric acid, and hydrated aluminum oxide.
The group VA flame retardant s work by forming a surface layer of protective char. These include phosphoric acid, diammonium orth ophosphate and others, which are usually applied in cellulose, polyester, and polyurethane products. Arsenic is usually not used as flame retardant owing to its toxicity, antimony in itself is ineffective as a flame retardant, and it is used only in combination with halogens, especially bromine and chlorine.
The group VII : A flame retardants which are the halogens (Bromine, chlorine and fluorine ). Bromine work s as a flame retardant in gaseous phase. When Bromine-containing compounds are incorporated into flammable materials, the bromine dissociates from th e material and form a heavy gas , when the materials is exposed to flame. The dissociation disperses heat and the bromine gas forms an insulating layer around the material. The layer prevents flames from spreading by inhibiting access to oxygen and by slowing the transfer of heat. The use of these groups of fire retardants is somehow restricted because of their environmental implications. The flame retardants selected for the present study are from group VA, which is incorporated in flexible polyurethane form as a reactive, not as an additive. Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics [5]. A urethane linkage is produced by reacting an isocyanate group, -N=C=O with a hydroxyl (alcohol) group, -OH. Polyurethanes are produced by the poly-addition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives [6].
During the production, excess isocyanate groups in the polymer with water or carboxylic acid produce carbon dioxide that blows the foam. Foaming reactions occur in three stages; the blow reaction lasts for about 12 seconds and occurs as soon as isocyanate reacts with polyol to give polyurethane and the polyurethane reacts further w ith isocyanate to produce an allopha nate in a reversible reaction.
R1NHCOOR 2 + R 3N = CO R1N (CONHR 3) COOR 2
INTRODUCTION
1.1 Background
Fire is a world wild problem which c laims lives and causes significant loss of properties. Most of the immediate surroundings of man consist of polymeric materials which are combustible materials. These include clothes , furniture, construction materials, and interior decorations. Generally, the interiors of homes, offices, vehicles, and packages are decorated with foamed plastics. The constitution of foamable polymeric materials made them liable to easy ignition and vigorous burning under right conditions. Humans have always been plagued by unwanted fire, which usually gulfed life and properties worth of millions of naira.
In addition to immediate fire risk pose d by the polymeric materials while burning, their combustion products often cause serious threat to human health and environment . In United States between 1996 and 2005 it was reported that an average of 3,932 human loss and another 20,919 injuries were as a result of fire accidents [1].
Recently, on 9 th Oct 2009, along Enugu -Onitsha express road, over ten vehicles loaded full with humans and property worth millions of naira were engul fed by fire. Therefore, the need to seek efficient and af fordable ways of reducing the flammability of polymeric materials in our sur roundings is of primary importance.
A flame is a rapid free radical , chain reaction of volatile materials with oxygen in the air. It is actually the resultant flame or fire that consumes life and properties. The term fire retardant (flame retardant) descri bes materials that inhibit or resist flammability of polymers . In the same vein a fire retardant chemical is used to denote a compound or mixture of compounds that when added to, or incorporated chemically into polymers, serve to slow down or hinder the ignition or growth of fire [2]. In other words, a flame retardant chemical is therefore a compound or mixture of compounds which when added to or chemically incorporated into a polymeric material, substantially suppresses the ease of ignition and/or flame pr opagation [3].
The above definitions of flame retardant denote that it generally either lower ignition susceptibility or lower the flame propagation once the ignition has occurred. The products on which flame retardants can be applied include apparels, carpets, and rugs, construction materials (thermal) insulation foams, wall coverings and composites to meet governmental regulations for buildings, aircraft, auto mobiles. Flame retardants can be incorporated into a material either as a reactive component or as an additive component. As a reactive, such flame retardants are incorporated into the polymer structure of the plastics , example, when polyurethane and polyamides are retarded with red phosphorus .
Flame retardants are usually classified into three typ es: non durable, semi durable and durable finishes, based on durability, or fastness to (laundry) light, heat chemicals etc . [3].
i. Non- durable finishes. These are used for packaging materials, paper and furnishings. They include formulations containing , borax and other borates. Others are aliphatic amine phosphate (e.g. triethanolamine phosphate) , urea sulphamates, ammonium and diammonium phosphate, ammonium bromide and ammonium polyphosphate.
ii. Semi durable finishes . These include flame retardants for mattresses, drapes, upholstery and carpets which can withstand 1-20 washings in water , for example, precipitate of a mixture of oxides of tungsten and tin in the soluble salts.
iii. Durable finishes . These retardants are very durable and can import excellent antimony oxide with durable functions to cotton fabrics, for example chlorinated paraffin.
Most flame retardants contain elements from group III A, (boron and aluminum) group VA (nitrogen, phosphorus, arsenic and a ntimony) and group VII A (fluorin e, chlorine and bromine) [4].
Group III : A flame retardant which contain boron or aluminum work by forming char which acts as a protective layer that prevents oxygen from reaching the inner layers of the material and thus sustaining the fire. Chemicals commonly used for this purpose include borax, boric acid, and hydrated aluminum oxide.
The group VA flame retardant s work by forming a surface layer of protective char. These include phosphoric acid, diammonium orth ophosphate and others, which are usually applied in cellulose, polyester, and polyurethane products. Arsenic is usually not used as flame retardant owing to its toxicity, antimony in itself is ineffective as a flame retardant, and it is used only in combination with halogens, especially bromine and chlorine.
The group VII : A flame retardants which are the halogens (Bromine, chlorine and fluorine ). Bromine work s as a flame retardant in gaseous phase. When Bromine-containing compounds are incorporated into flammable materials, the bromine dissociates from th e material and form a heavy gas , when the materials is exposed to flame. The dissociation disperses heat and the bromine gas forms an insulating layer around the material. The layer prevents flames from spreading by inhibiting access to oxygen and by slowing the transfer of heat. The use of these groups of fire retardants is somehow restricted because of their environmental implications. The flame retardants selected for the present study are from group VA, which is incorporated in flexible polyurethane form as a reactive, not as an additive. Polyurethanes are in the class of compounds called reaction polymers, which include epoxies, unsaturated polyesters, and phenolics [5]. A urethane linkage is produced by reacting an isocyanate group, -N=C=O with a hydroxyl (alcohol) group, -OH. Polyurethanes are produced by the poly-addition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives [6].
During the production, excess isocyanate groups in the polymer with water or carboxylic acid produce carbon dioxide that blows the foam. Foaming reactions occur in three stages; the blow reaction lasts for about 12 seconds and occurs as soon as isocyanate reacts with polyol to give polyurethane and the polyurethane reacts further w ith isocyanate to produce an allopha nate in a reversible reaction.
R1NHCOOR 2 + R 3N = CO R1N (CONHR 3) COOR 2