OPMENT. Kamil Sławęcki

Transcription

1 Rzeszów University of Technology Thee Faculty of Chemistry Departmen nt of Industrial and Materials Chemistry MASTER S THESIS DEVELO OPMENT OF NEW P, N AND B-BASED FLAME RETARDANT Kamil Sławęcki Supervisor: Dr. Eng.Agnieszkaa Bukowska Rzeszów 2010

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3 Experimental work was performed at EMPA Swiss Federal Laboratories for Material Science and Technology Sankt Gallen Switzerland Under the direction of Dr Axel Ritter Heartfelt thanks Mrs. Dr. Eng. AgnieszkaBukowska For her valuable guidance and assistance during the writing thesis. 3

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5 Index of content: Index of content... 5 SCOPE AND PURPOSE OF WORK... 7 List of abbreviations... 9 INTRODUCTION LITERATURE OVERVIEW Polymer Combustion Flame retardation Mechanism of Nylon 6 Pyrolysis Flame retardant compounds Mode of action of flame retardants Physical action Chemical action Important flame retardants Halogen-containing flame retardants Phosphorus flame retardants Nitrogen-containing flame retardants Phosphorus-nitrogen synergism Inorganic flame retardants Silicon containing compounds Flame retardant testing methods Thermogravimetric analysis Limiting oxygen index PCFC Cone Calorimeter EXPERIMENTAL PART Materials Laboratory equipment Synthesis of flame retardant Evaluation of thermal stability Total melting point Thermogravimetric analysis Rheological influence effect of flame retardant on PA6 and PET Kneadling test Flammability properties

6 2.6.1 Pyrolysis Combustion Flow Calorimeter Limited Oxygen Index Qualitative Analysis Nitrogen Content Analysis Phosphor, Boron, Magnesium Content Analysis RESULTS AND DISCUSION Evaluation of thermal stability by total melting point (TMP) and thermogravimetric analysis Evaluation of rheological influence of additives on PA6 and PET by thermo electron corporation set: Haake Polylab Rheodrive16 and Haake RheomixOs Evaluation of flammability by pyrolysis Combustion Flow Calorimeter (PCFC) And Limited Oxygen Index (LOI) SUMMARY AND CONCLUSIONS REFERENCES DIPLOMA THESIS (MS) ABSTRACT

7 SCOPE AND PURPOSE OF WORK Purpose of work The goal of the research was to find new flame retardant compounds for synthetic polymers such a PET or PA6, using various means of flame retardants, containing, inter alia, heteroatoms such as phosphorus, boron and nitrogen. Flame retardants obtained through synthesis. Scope of work Scope of work comprised: Literature overview, selection of the compounds of phosphour, boron, nitrogen synthesis of flameretardants, evaluation of thermal stability obtained product, application of flame retardant to PET and PA6, indication of flame resistance of polyester and polyamide with flame retardant admixture, analysis of the results, 7

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9 List of abbreviations BA - Boric Acid, DA - DiethyleneTriaminePenta (Methylene Phosphonic Acid), DMT - 2,4-Diamino-6-methyl-1,3,5-triazine, DPT - 2,4-Diamino-6-phenyl-s-triazine, EA - Ethylenebis(nitrilodimethylene)tetraphosphonic Acid, FR - Flame Retardant, LOI - Limited Oxygen Index, Mel - Melamine, NA - Nitrilotris(methylene)triphosphonic Acid, ICP - Inductively Coupled Plasma, PA - Phytic Acid, PA6 - Polyamide 6, PCFC - Pyrolysis Combustion Flow Calorimeter, PET - Polyethylene terephthalate, PVM - Poly(vinylmelamine), TGA - Thermogravimetric Analysis, TMP - Total Melting Point. 9

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11 INTRODUCTION Plastics and textiles find many uses and add greatly to the quality of modern-day life. However, a major problem arises because most of the polymers no which these material are based are organic and thus flammable. In UK alone some deaths and roughly injuries result from fire each year. Most of the deaths are caused by inhalation of smoke and toxic combustion gases, carbon monoxide being the most common cause, whilst the injures result from exposure to the heat evolved from fires. In addition, the annual cost of damage to buildings and loss of goods varies between 0.5 billion and 1.0 billion. Thus, there are great economic, sociological and legislative pressures on the polymer industries to produce materials with greatly reduced fire risk [1]. The development of fire retardant polymers is undertaken to reduce the likelihood of unwanted fires. If the first item exposed to an ignition source does not ignite or propagate flame, a fire might never start. If ignition does occur, flame retarded products usually reduce the spread of flame or the rate of burning compared to nonflame retarded products [2]. The demand for textile flame retardancy is mainly in work clothing, fire-fighter apparel, institutional draperies, institutional upholstery, institutional and commercial carpet, transportation especially aircraft, military garments, professional racers garments, and bedding [3]. 11

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13 1. LITERATURE OVERVIEW 1.1Polymer Combustion Natural and synthetic polymers, when expose to a source of sufficient heat, will decompose or pyrolyse evolving flammable volatiles. These mix with the air and, if the temperature is high enough, ignite. Ignition occurs either spontaneously (auto ignition) or due to the presence of an external source such as spark or flame (flash ignition). If the heat evolved by this ignited flame is sufficient to keep the decomposition rate of the polymer above that required to maintain the concentration of the combustible volatiles, i.e. the fuel, within the flammability limits for the system, then a self-sustaining combustion cycle will be established. Figure 1.1 is a simple representation of this behavior. Combustion products FLAME Decomposition products HEAT POLYMER Fig. 1.1 Simple representation of polymer combustion processes [1]. Combustion reactions liberate the energy stored in the chemical bonds of the molecules of the fuel. A fuel is any substance that will release energy during reaction with oxygen, usually in air, generally initiated by an external heat source. Typical fuels are organic materials as are most synthetic polymers. Polymer combustion is a complex process involving a multitude of steps and is best described in qualitative terms. Figure 1.2 is a schematic diagram of the various steps which combine to establish the polymer combustion process. The tree essential stages required to ignite the combustion are heat, thermal desorption or pyrolysis and ignition. Ignition is normally caused by the presence of an external heat source such as flame or a spark or, if the temperature is high enough occurs spontaneously. 13

14 non-combustible gases Polymer pyrolysis endothermic combustible gases gas mixture air ignites flame liquid products exothermicity solid charred residue air embers thermal feedback Fig. 1.2 Schematic representation of many processes involved in polymer combustion [1]. The temperature of the solid polymer is raised either due to an external heat source such a radiation or flame, or by thermal feedback as indicated on Fig During the initial exposure to heat thermoplastics, which have a linear chain structure, soften or melt and start to flow. On the other hand, thermosetting plastics have a threedimensional cross-linked molecular structure which prevents softening or melting. Additional heat causes both types of polymer to pyrolysis and evolves smaller volatile molecular species. Because of their structure this occurs at higher temperatures for thermosetting as opposed to thermoplastics polymers. Since most plastics are organic in nature the evolved species provide the fuel to sustain the flame. Thus we see that mechanism of combustion contains both a condensed phase and a vapour phase contribution [1]. Pyrolysis is an endothermic process which requires the impute of sufficient energy to satisfy the dissociation energies of any bonds to be broken plus any activation energy requirements of the process. As individual polymers differ in structure, their decomposition temperature ranges vary within certain limits. The limits will again change somewhat when a polymer is compounded with various additives and subsequently processed to produce what are commonly known as plastics [1]. 14

15 1.2 Flame retardation Major interest in the plastics and textiles industries is not the fact that their products burn but how to render them less likely to ignite and, if they are ignited, to burn much less efficiently. A schematic representation of self-sustaining polymer combustion cycle is shown in Fig Flame retardants act to break this cycle, and thus extinguish the flame or reduce the burning rate, in the number of possible ways: by reducing the heat evolved to below that required to sustain combustion by modifying the pyrolysis process to reduce the amount of flammable volatiles evolved in favour of increasing the formation of less flammable char which also acts as a barrier between the polymer and the flame (I) by isolating the flame from the oxygen air supply (II) by introducing into the plastic formulations compounds which will release chlorine or bromine atoms if the polymer is heated to near the ignition temperature. Chlorine and particularly bromine atoms are very efficient flame inhibitors (III) by reducing the heat flow back to the polymer to prevent further pyrolysis. This can be achieved by the introduction of a heat sink, e.g. magnesium oxide which decomposes endothermic ally or by arranging that a barrier, e.g. chair or intumescent coating, is formed when the polymer is exposed to fire conditions (IV) by development inherently flame retardant systems[1]. 15

16 Smoke & Gaseous species Heat IV Flame III II Flammable volatiles Oxygen (air) Polymer pyrolysis I Fig. 1.3 Schematic representation of the self-sustaining polymer combustion cycle; I - IV represent potential models of flame retardant action [1]. Combustibility can depend as much on fire conditions as on polymer composition. Whether a material is a flame retarded material is very much in the context of tests. Whereas designing laboratory tests which measure fundamental properties, then using those properties in mathematical models, is becoming increasingly successful. The behavior of materials in a fire can be described by several factors: ease of ignition how readily a material ignites, flame spread how rapidly fire spreads across a surface, fire endurance how rapidly fire penetrates a wall or barrier, rate of heat release how much of heat is released and how quickly, ease of extinction how rapidly or how easily the flame chemistry leads to extinction, smoke evolution amount, evolution rate, and composition of smoke released during stages of fire, toxic gas evolution amount, evolution rate, and composition of gases released during stages of fire [2]. Most flame retardant systems in use today have been developed empirically. Current interest is obtaining a better understanding of polymer combustion and interactions of flame retardants there with is motivated by the requirement to develop environmentally friendly flame retardant systems with enhanced performance [1]. 16

17 1.3 Mechanism of Nylon 6 Pyrolysis As engineering resins, aliphatic nylons shows high toughness over a wide range of temperatures, together with impact and absorption resistance, lubricity and good resistance to organic solvents. Aliphatic nylons are used in many demanding applications where the properties of thermal stability and fire resistance are priorities [4,5]. Because of this high practical interest, the thermal decomposition of aliphatic nylons has been studied extensively. The thermal decomposition of various nylon samples, including nylon 6, having molecular weights of about and about was studied by Staraus and Wall [6]. It was found that heavy volatile products comprised about 95wt% of total volatiles. No attempts were made to analyze this wax like fraction.however, it was estimated that it mostly contains chain fragments largerthen five monomeric units. There was no outstanding individual exception of CO 2 and probably H 2 O, but as the polymer decomposes a large number of different compounds are produced as minor products, such as H 2, CH 4 and CO. It was suggested that the weakest C N bonds undergo the initial scission. On the basis of volatilization rate measurement and product analysis, a random or nearly random type of breakdown was indicated for nylon 6 decomposition. Hydrolytic scission of the peptide C(O)-NH bond was assumed to explain the high concentration of CO 2 arising from the decomposition of the acid groups produced by the hydrolytic scission. Kamerbeck et al, [7] studying the thermal decomposition of nylon 6, postulated two types of reaction: primary reactions which take place at temperatures below 300 C and secondary reactions, which mostly begin at temperatures above 300 C. It was assumed that the thermal decomposition of nylon 6 starts with homolytic scission of the N-alkylamide bond. Primary amide, nitrile, vinyl, isocyanate and alkyl chain ends are generated (1.1). 17

18 O NH NH NH 5 4 O O O NH NH NH + 5 H2C 4 O O H + -H. O NH 2 NH 5 3 O O -H 2 O O O NH 5NCO + 3 NH 5CN O NH NH (1.1) Dussel et al [8] carried out pyrolysis of nylon 6 in the inlet system of a field ion mass spectrometer at 530±800 C. They found amines, amides and nitriles to be characteristic fragments of thermal decomposition. Homolytic scission of N-alkylamide or peptide (i.e. nitrogen-carbonyl) bonds was suggested (1.2). NH NH 5 4 O O NH O H -H 2 O O NH 2 (1.2) O CN Similar to Dussel et al, [8] the homolytic scission of the N-alkylamide or peptide bonds in nylon 6 was considered by Ohtani et al [9] in their pyrolytic gas chromatography experiments at 550 C. They found the predominant volatile product from nylon 6 was caprolactam, with only a minor nitrile peak. A similar conclusion was drawn by Michal et al [10] in pyrolysis experiments using the Curie point heating 18

19 method at 510, 610 and 770 C. Apart from caprolactam, only hydrocarbons and acrylonitrile were detected at significant levels. 1.4 Flame retardant compounds Flame retardant compounds, in order to be useful, must fulfill a complex set of requirements, many of which are specific for each material and derived product. A flame retardant added to a polymer should: reduce flammability compared to the unmodified polymer to a level specified for the flame-retardant product in terms of product performance measured in a specific flammability test, reduce smoke generation under specific conditions of testing, not increase the toxicity of combustion products from the modified polymer as compared to unmodified polymer, be retained in the product through normal use, have an acceptable or minimal effect on other performance properties of the product in use. Flame retardants are usually compounds containing halogens, phosphorus, nitrogen, sulfur, boron, and metals in different combinations. When two compounds function as flame retardants, the result may be additive, synergistic, or antagonistic. An additive effect is the sum of the effects of two components measured independently. A synergistic effect is an observed effect greater than the additive effect, and an antagonistic effect is one which is less than an additive effect. There have been many attempts to classify flame retardants according to a single characteristics [11, 12]. In most cases the characteristics used to classify flame retardants are: a general chemical nature (inorganic, organic, etc.), the presence of an element or a combination of elements promoting flame retardancy (phosphorus, nitrogen, halogen, etc.), the means of incorporation, (additive or reactive), chemical type (acids, bases, ethers, esters, oxides, hydroxides, salts, etc.), 19

20 mechanism of action (physically or chemically active flame retardants; flame retardants which are active in the gas or condenced phases), the durability of fastness (to laundry, light, heat, chemicals, etc.). 1.5 Mode of action of flame retardants Depending on their nature, flame retardants for synthetic and natural polymers can act chemically and/or physically in the solid (condensed) or gas (vapor) phase by interfering with one or more stages of the combustion process: heating, decomposition, ignition, flame spread, or smoke process Physical action There are several ways in which the combustion process can be retarded by physical action: By cooling. The degradation reactions of the fire retardant can influence the energy of the combustion. The flame retardant can degrade endothermally which cools the substrate to a temperature below the one required for sustaining the combustion process (e.g. metal hydroxides). By formation of a protective layer. This group of flame retardants includes low melting point inorganic salts which, upon contact with a flame, fuse to cover the fiber with a glassy layer [13]. This coating layer may be formed on fiber surfaces during normal chemical processing or when the fiber and retardant are heated to near combustion temperatures. The coating must be stable at typical burning temperatures of about C. Common examples are boric acid borax systems, silicates, phosphates, and polyphosphates [14]. By dilution (evolve of nonflammable gases). These compounds, when used as additives on cellulose fibers, decompose readily at elevated temperatures with the evolution of inert or uneasily 20

21 oxidizable gases such as CO 2, NH 3, HCl, H 2 O, and SO 2. These gases are nonflammable, and they help in flame retardation by dilution of the accompanying flammable gases produced during pyrolysis. They may also blanket fiber surfaces and reduce the prevailing oxidizing atmosphere of the environment [13]. Examples of this kind of flame retardant are sodium carbonate and bicarbonate; the ammonium halides, phosphates, and sulfates; the chlorides of zinc, calcium, and magnesium [13]. The incorporation of inert substances (e.g. fillers) and flame retardant additives (which evolve as inert gases on decomposition) dilutes the gases feeding the flame so that the lower ignition limit of the gas mixture is not reached (e.g. metal hydroxides) Chemical action The chemical reactions interfering with the combustion process take place in the solid and gas phases. Reactions in the gas phase. Flame retardants act in the gas phase by producing free radical terminators when heated to flaming temperatures. Oxidation in the gas phase is a free radical process in which free radicals, such as H, OH and HO 2 are formed, and these propagate combustion and also the exotermic processes, which occur in the flame, are inhibited, the system cools and the supply of flammable gases is reduced and eventually completely eliminated (e.g. halogenated flame retardants). When thermal degradation of a compound results in formation of free radicals which can then react with these, it shows flame retardation properties. Halogen containing flame retardants function via this mechanism [14]. Reactions in the solid phase. These retardants change the decomposition process in such a way that amount of flammable gases and tars produced is minimized, and correspondingly the amount of char formed is increased [12]. This increase in amount of char formation results from the catalytic dehydration of cellulose when it reacts with 21

22 a Lewis acid via a carbonium ion mechanism. Many flame retardants, especially those based on phosphorus and nitrogen, operate by this mechanism. Also we can select three types of reaction in solid phase: The breakdown of a polymer (thermoplastic) can be accelerated by flame retardants, causing pronounced flow or drip of the molten polymer and, hence, its withdrawal from the environment of the flame. Flame retardants can form a layer of carbon (charring) on the surface of the polymer upon combustion. This process can occur, for example through the dehydrating action of the flame retardant generating double bonds in the polymer (usually in polymers containing hydroxyl groups). These processes form a carbonaceous layer via cyclizing and cross-linking (e.g. phosphorus compounds). Another mechanism of flame retardation in the condensed phase is intumescence. When exposed to heat in which materials swell to form foam, usually carbonaceous, which in turn acts as a barrier to heat, air and pyrolysis products. Intumescent systems are based on three basic ingredients: a catalyst, a charring agent and a foaming (spumific) agent. 1.6 Important flame retardants Most of the chemicals used in fire-retardant formulations have a long history of use for this purpose, and most formulations are based on empirical investigations for best overall performance. These chemicals include the phosphates, some nitrogen compounds, some borates, silicates, and more recently, amino-resins. Phosphorus and nitrogen are frequently used together because they behave synergistically; amino-resins are an example of such a combination. Typically, these flame retardants systems inhibit or even suppress the combustion process by chemical or physical action in the gas or condensed phase. These compounds reduce the flame spread of substance but have diverse effects on strength, hydroscopicity, durability, machinability, toxicity, gluability, and paintability [15-17]. 22

23 1.6.1 Halogen-containing flame retardants Halogen-containing flame retardants are one of the largest groups of additives in the plastic industry. They are used primarily in polymers for the electronic and building industries and are known for their performance in styrenic copolymers, engineering thermoplastics, and epoxy resins. There are three types of halogen-containing compounds that are used as flame retardants: derivatives of compounds with aliphatic, cycloaliphatic, and aromatic structures. The type of halogen atom is varied in each class. Halogenated flame retardants act by inhibiting the radical mechanism which takes place during the combustion. In the gas phase, high-energy OH and H radicals are formed by chain branching: H + O 2 OH + O (1.3) O + H 2 OH + H (1.4) The main exothermic reaction involves OH radicals: OH + CO CO 2 + H (1.5) When exposed to high temperatures, halogenated flame retardants decompose to release halogen, as free radicals X. These radicals react with hydrocarbon molecules to give the hydrogen halide HX. Then the high-energy radicals OH and H are removed by reaction with HX and replaced by low-energy X radicals. The actual flame retardant effect is thus produced by HX. The hydrogen halide consumed is regenerated by reaction with hydrocarbon. RX R + X (1.6) X + RX R + HX (1.7) 23

24 HX + H H 2 + X (1.8) HX + OH H 2 O + X (1.9) The effectiveness of halogenated flame retardants depends on the quantity of the halogen atoms they contain and also, very strongly on the control of halogen release. Flame-ignition studies on halogens have shown that the effectiveness increases in the order F <Cl<Br < I. Bromine and chlorine compounds are generally used because iodine compounds are thermally unstable at polymer processing temperatures, while fluorine compounds are too stable. To be more effective, some halogenated flame retardants require the presence of other elements, and particularly metal oxides, have excellent flame retardant properties [11]. For example, antinomy oxides (Sb 2 O 3 ) act as synergistic catalyst [11, 12, 18]. It acts by facilitating the breakdown of halogenated flame retardants to active molecules. Sb 2 O 3 also reacts with the halogens to produce volatile antinomy species (antinomy halides or antinomy oxyhalides), which are capable of interrupting the combustion process by removing OH and H radicals. The use of PVC-Sb 2 O 3 combinations was discussed by Horrocks [19]. Although halogenated compounds (chlorine and bromine) form some of the most widely employed flame retardant materials, they have clear disadvantages: the potential to corrode metal components, and the toxicity of hydrogen halides formed during combustion. Thus, there is a growing demand to replace halogen-containing flame retardants Phosphorus flame retardants Phosphorus-containing compounds are used as flame retardants for thermoplastics, thermosets, textiles, paper, coatings and mastics. Most of these flame retardants contain phosphorus from the -3 to +5 oxidation state and include inorganic phosphates, insoluble ammonium phosphates, organophosphates and phosphates, chlorophosphates and phosphonates, phosphonium salts, phosphines, and oxides. Many reviews of phosphorus-containing flame retardants have been published [11, 16, 19-22]. 24

25 On commercial basis, phosphorus compounds become increasingly expensive on progressing from the +5 to -3 oxidation states. Hence, phosphates are less expensive than phosphines. However, stability increases conversely with the trend phosphates < phosphates <phosphonates< phosphine oxides. Because of synergy, the most successful of these retardants contain nitrogen in combination with phosphorus [14]. The flame-retardant mechanism for phosphorus depends on the type of phosphorus compound used and on the chemical structure of the polymer. Phosphoruscontaining flame retardants mainly act in the condensed phase. The flame retardant is converted by thermal decomposition to phosphoric or polyphosphoric acid. This acids act as dehydrating agents (extracting water from the pyrolysing substrate), altering the thermal degradation of the polymer, and promoting the formation of char. The char insulates the polymer substrate from heat, flame, and oxygen. A key feature of phosphorus flame retardants is intumenscence [1, 23, 24]. Intumescent coatings are made from a combination of products, which are applied to a surface like paint. The products involved contain: a carbonific (char former) such as a polyol, an acid source or a catalyst (phosphorus compounds), a spumific compound (amines or amides which liberate non-flammable gases such as NH 3 or CO 2 when heated), and a resin binger. The mechanism of intumescence involves the decomposition of the phosphorus compound to phosphoric acid, esterification of the polyol to form polyol phosphate and char formation through a series of elimination steps. Like halogenated compounds some phosphorus compounds can act in the gas phase, through the formation of PO radicals. Flame-inhibition reactions similar to the halogen radical trap mechanism have also been proposed [2, 24]: H 3 PO 4 HPO 2, HPO, PO (1.10) PO + H HPO (1.11) HPO + H H 2 + PO (1.12) PO OH + H 2 HPO + H 2 O (1.13) 25

26 Although phosphorus compounds are highly effective flame retardants and an alternative to halogenated compounds, they are not effective in all types of polymers. They work well in oxygen- or nitrogen-containing polymers but unsatisfactory in polymers which do not char (polyolefin, styrenic resins) Nitrogen-containing flame retardants Nitrogen containing flame retardants are environmentally friendly because they are less toxic. There are no dioxin and halogen acids by-product and low evaluation of smoke during combustion. But nitrogen, when present alone in a compound, does not have good flame retardant properties. As much as 17% nitrogen is required to render cotton moderately flame retarded [12, 25]. Its importance lies in its synergistic activity with phosphorus when both elements are introduced into a cellulose substrate. Quantitatively, the interaction of nitrogen and phosphorus was evaluated by Tesoro and coworkers [26], Willard and Wondra [25], and Reeves et al. [27]. These workers observed that on increasing the nitrogen level to a fabric, with a constant level of phosphorus incorporation, the flame retardant effect was greater than additive. Willard and Wondra [27] further showed that phosphorus-nitrogen synergism on cellulose is not a general phenomenon but is depend upon the chemical nature of nitrogen compounds. The best results are obtained with a substituted melamine, while urea derivatives are less effective. When nitrogen is present as a tertiary amine group, the flame retardant interactions are antagonistic. The mechanism of nitrogen-containing flame retardants are not fully understood, but it is thought that they have several effects: formation of cross-linked molecular structures in the treated material. These are relatively stable at higher temperatures, thus physically inhibiting the decomposition of materials to flammable gases (needed to feed flames), release of nitrogen gas which dilutes the flammable gases and thus reduce flames, synergy with phosphorus-containing flame retardants by reinforcing their function [2, 28-30]. 26

27 The most important reactive type organic nitrogen flame retardants are melamine and its derivatives [31, 32]. Melamine phosphates and pyrophosphonates are another distinct type of flame retardants, some are already commercially available, but more applications and mechanistic studies are needed. A good review on several melamine phosphoric acid salts in coating applications, such as chlorinated rubber, vinyl and epoxy coatings is given by Weil and McSwigan [32]. They have been applied in systems such as intumescent coatings, rigid PU foam or nylons and ABS. For example, in the PU foam application, the heterocyclic aromatic structure of melamine (2,4,6-triamino-1,3,5-triazine) (Fig. 1.4) provide both thermo-stability and char forming ability, therefore impart better flame retardancy than heterocyclic aliphatic structures, such as oxazolidonic, imidic, isocyanuric type compounds [33, 34]. NH 2 N N H 2 N N NH 2 Fig. 1.4 The structure of melamine. More interestingly, novel nitrogen containing polymers with inherent flame retardant properties are being developed. Oxazene resin is one of such new development to be used as homopolymer or with epoxy resin formulation [35]. It has advantages from both brominated epoxy resin and phenoplasts, i. e. good mechanical and electrical properties, good processing characteristics and low density, toxicity and corrosiveness. Such properties are very important in materials of high strength fibre reinforced polymers or electronic laminates. It is especially effective when combined with a phosphorus containing epoxy resin [36]. Nitrogen-based compounds can be employed in flame retardant systems or form a part of intumescent flame retardant formulations. They are mainly found in polymers such as polyurethane and polyamides. Melamine-based products such as melamine, melamine phosphate, and melamine cyanurate are currently the most widely used nitrogen flame retardants. The main advantages of nitrogen-containing flame retardants are their low toxicity, their solid state under standard conditions, and in case of fire, the absence of 27

28 dioxin and halogen acids as combustion products and their low evolution of smoke. Thus, they are environmentally friendly compared to halogenated compounds Phosphorus-nitrogen synergism One role of phosphoric acid and phosphate compounds play in the fire retardancy of cellulose is to catalyze the dehydratation reaction to produce more char. However, this reaction is always in competition with the other reactions that are taking place (i. e., decarbonylation, condensation, decomposition). The effectiveness of fire retardants containing both phosphorus and nitrogen is greater than the effectiveness of each of them by themselves. The mechanism of a particular fire retardant is the summed effect of all simultaneous reactions. This summed effect is especially evident in the synergism of some compounds; the effect of two compounds together is greater the summed effect of each individual one alone [37, 38]. Phosphorus and nitrogen compounds produces a more effective catalyst for the dehydration because the combination leads to further increases in the char formation and greater phosphorus retention in the char [38]. This result may be caused by the cross-linking of the cellulose during pyrolysis through ester formation with the dehydrating agents. Also the presence of amino groups causes retention of the phosphorus as a nonvolatile amino salt, in contrast to some phosphorus compounds that may decompose thermally and be released into the volatile phase. Another possibility is that the nitrogen compounds promote polycondensation of phosphoric acid to polyphosphoric acid [37]. Polyphosphoric acid might also serve as a thermal and oxygen barrier because it forms a viscous fluid coating [39]. Whatever the particular mechanism is, it is apparent that some other reactions are preceding the dehydratation reaction in order to make it more effective Inorganic flame retardants A number of inorganic compounds are used as flame retardants, interfering by various physical actions with the combustion process: release of water or nonflammable gases which dilute the gases feeding the flame, absorption of heat energy 28

29 thus cooling the substrate, or production of a non-flammable and resistant layer on the surface material. Inorganic flame retardants include metal hydroxides and boron compounds. Metal hydroxides Metal hydroxides are an important class of flame retardants. They are used an almost every class of polymers such as polyolefin, thermosets, and in electronic, wire and cable applications. The most widely employed metal hydroxides are aluminium trihydroxide (ATH) and magnesium hydroxide. Metal hydroxides used as flame retardants interfere with the combustion process at many levels. They first decompose endothermally to metal oxide (which forms a protective non-flammable layer on the substrate surface) and to water: 2 Al(OH) 3 Al 2 O H 2 O (1.14) Mg(OH) 2 MgO + H 2 O (1.15) The water (as steam) forms a layer of non-flammable gas near the substrate surface inhibiting flames. The endothermic decomposition absorbs heat energy to cool the substrate and slow down the burning. All hydroxides are relatively non-toxic, but for meeting fire performance requirements, extremely high loadings are necessary which can affect the properties of the polymers. Flame retardant treated polymers usually produce more dense smoke than untreated ones during pyrolysis and combustion. Lewin [40] reviewed the mechanism of formation of smoke in flame retardant treated polymers and possible modes of its inhibition. One of the methods mentioned for smoke reduction is to use metallic salts or complexes as additives. The effect of metallic agents like titanium, antimony, and molybdenum was reported by several workers [19]. Kauret at.reacted metal ions (chromium, manganese, cobalt, nickel, copper, zinc, zirconium, molybdenum, silver, candium, and mercury) chemically with cellulose phosphate and cellulose ammonium phosphate [41, 42]. 29

30 Boron-containing compounds Flame retardants containing boron are mostly used for flame retarding wood rather than textiles. They are water soluble and are easily removed by water, rain, or perspiration and are suitable for applications where they will not come in contact with these fluids. They are useful for disposable fabrics, insulation, wallboards, theatrical scenery, packaging material, paper, etc. Examples of boron containing flame retardants are boric acid (H 3 BO 3 ) and sodium borate (Na 2 B 4 O 7 ) [14]. The borates have low melting points and form glassy films on exposure to high temperatures. Borax inhibits surface flame spread but also promotes smoldering and glowing. Boric acid reduces smoldering and glowing combustion but has little effect on flame spread. Because of this, borax and boric acid are usually used together [38] Silicon containing compounds Silicon containing flame retardants mostly use as additives to the polymers. Considerable research has shown that the addition of relatively small amounts of silicon compounds, especially when added to intumescent formulations [43-45] to various polymeric materials can significantly improve their flame retardancy, through both char formation in the condensed phase and the trapping of active radicals in the vapour phase. Silicon containing flame retardants are considered to be environmentally friendly additives because their use is claimed to lead to a reduction in the harmful impact on environment [45-47]; little, if any, scientific evidence exists to substantiate this claim, however. Silicone fluids have been widely used in the polymer processing industry as internal lubricants to reduce wear and improving mould release. It was shown that a silicone in conjunction with a metal soap can provide a degree of flame retardancy for certain thermoplastics [48]. Lower viscosity silicones in combination with a metal stearate show some flame retardancy, but tend to give flaming drips. The incorporation of silicones often produces slight intumescent char formation in polypropylene, while the polymer itself burns without a char [49]; this solid phase reaction appears to be the main mode for the silicon flame retardant action. It is concluded that a combination of a linear polydimethylsilicone and other optional components can effectively flame retard polypropylene. It is a transparent, viscous silicone polymer and is usually used with one or more co-additives, such as ammonium 30

31 polyphosphate and pentaerythritol that act as synergists both in polypropylene. The additives also help to mix the two polymers together and aid char formation. These observations have been substantiated in works by Zhang et. al [49] in attempts to produce synergistic Si-P retardant combinations at lower concentrations more suitable for fiber applications. Other advantages of the silicone based additives are that they can improve the impact resistance dramatically and add conventional silicone properties of improved mouldability, processibility, gloss and electric insulating properties. 1.7 Flame retardant testing methods Knowledge of various test methods used to evaluate the effectiveness of fire retardants is necessary to understand the mechanisms of fire retardants. The commonly used tests methods applicable to evaluate fire retardant treatments include thermogravimetric analysis (TGA), limiting oxygen index (LOI) and burning test. Other test methods are used to evaluate the effect of fire retardant treatments on such related properties as smoke development, heat release rate, and toxicity [50] Thermogravimetric analysis The simplest method of evaluating the thermal properties of flame retardant compounds is by thermogravimetric analysis (TGA). Fig 1.5 shows a schematic of the equipment used for this analysis. A sample is passed in a metal pan in a furnace tube. Nitrogen gas is passed through the system and the furnace tube is slowly heated at a constant rate. Also nitrogen or another gas flows around the sample to remove the pyrolysis or combustion products. The percent of weight loss is measured as function of temperature and is printed out on a strip chart. The temperature is usually raised to C in nitrogen at a rate of a few degrees Celsius per minute. The temperature is then lowered to around C, oxygen is introduced into the system, and the temperature is increased again. This second scan shows the combustion of the char in oxygen. 31

32 Fig. 1.5 Schematic diagram off a simple thermogravimetric analysis systemm [2]. Weight loss is recorded as a function of temperature (see Fig.1.6): Fig.1.6 Thermogravimetricanalysis of aliphatic nylons [51]. Upon thermal decomposition in an inert atmosphere with linear heating, nylonn 6 shows three steps of weight loss [51]. Thermogravimetry curves for nylon 6 and other aliphatic polymers are shown in Fig 1.6 [52-54].The first step which w is most evident on the derivative curve was attributed to the volatilization of residual moisture and low molecular weight oligomers. The secondd step, in a temperature e range of 280±450 C, is the major decomposition step of nylon because most material volatilizes at this 32

33 temperature. In this stage probably a crosslinked structure is also formed. Together with the reactions discussed above, polymerization of unsaturation created by alkyl - amide bond scission might also contribute to crosslinking. Because a more thermally stable structure is formed, the rate of weight loss slows down at about 450 C. On further heating, the crosslinked structure decomposes and yields about 5% of thermally stable char Limiting oxygen index Oxygen index methods, which describes the tendency of a material to sustain a flame, are widely used as a tool to investigate the flammability of polymers. They provide a convenient, reproducible, means of determining a numerical measure of flammability. A further attraction is that the test method uses inexpensive equipment and only requires a small sample size [55]. The quintessential feature of oxygen-index methods is that the sample is burnt within a controlled atmosphere. The standard procedure is to ignite the top of the sample, using a gas flame which is withdrawn once ignition has occurred, and to find the lowest oxygen concentration in an upward flowing mixture of nitrogen and oxygen which just supports sustained burning. The criticality criterion typically takes the form of a minimum burning length: either specifying that the sample must burn for a certain length of time or that a specified length of material be consumed. The effectiveness of fire retardants is measured by the change in the critical oxygen concentration that they induce as a function of their concentration. The apparatus holds a small-scale sample of material (typically a fabric) which is clamped vertically in a tube in an atmosphere where the relative concentration of oxygen and nitrogen can be changed. The aim is to test the flammability of the sample with a small pilot flame to find the minimum oxygen concentration required to sustain combustion in the sample (Fig. 1.7): 33

34 Fig.1.7 Scheme of the apparatus for LOI [55]. The limiting oxygen index (LOI),, also called the critical oxygen index (COI) or oxygen index (OI), is defined as: LOI = O 2, cr O 2, cr N 2 where [O 2,cr ] and [N 2 ] are the minimum oxygen concentration in the inflow gases required to pass the ``minimumm burning length'' criterion and the nitrogen concentration in the inflow gases respectively. If the inflow gases are maintainedd at constant pressure then the denominator of these formulas is constant since any reduction in the partial pressure (concentration) of oxygen is balanced by a corresponding increase in the partial pressure (concentration) of nitrogen. Limiting oxygen index is more commonly reported ass a percentage rather than fraction. This method is suitable as a semi-qualitative indicatorr of the effectiveness of flame retardants during the research and development stage. Polymeric materials having LOI value of 21% or below ignite easilyy and burn rapidly in the air (containing 20.8% 34

35 of oxygen). Those with LOI values above 21 ignite and burn more slowly and generally, when LOI values rise above 21 ignite and burn more slowly and generally, when LOI values rise above approximately 26-28, the polymers may be considered to be flame retarded [56]. However, this test method is not appropriate as a predictor of real scale fire performance mainly because of the low heat input and the simulated high oxygen concentration PCFC Cone Calorimeter The cone calorimeter test is a medium size test which was originally developed at NIST [57] and quickly gained popularity in the academic community as well as for standardization purpose. It is also used as a tool for fire protection engineering, because it allows prediction of some large-scale test results, in particular flash-over time which is important for time to escape. In the cone calorimeter, heat and smoke release rate is measured together with mass loss and ignitability, under a wide range of radiant heat exposure conditions. At the start of a test, a square specimen of 100 x 100 mm is placed on a load cell and exposed to a preset incident heat flux from a truncated cone radiant heater, which can be set to fluxes representing small fires to fully developed fires. An electric spark ignition source is used for piloted ignition. The combustion products and entrained air are collected by a hood and extracted trough a duct by a blower. Heat release rate is calculated from oxygen concentration measurements based on the oxygen consumption principle. 35

36 Fig. 1.8 Scheme of the Cone Calorimeter r [2]. Apart from heat release rate, the conee calorimeter can also monitor time to ignition, weight loss of the sample during combustion, effective heat of combustion (heat generated per unit mass loss), rate of smoke generation, carbon monoxide, carbon dioxide and optionally some corrosive gases like HCl or HBr. 36

37 2. EXPERIMENTAL PART 2.1. Materials 10% water solution of ammonia NH 4 OH diluted from 25% solution in water, Hanseler AG, Aluminium Trihydroxide Al(OH) 3, Sigma-Aldrich, Boric Acid H 3 BO 3, Sigma-Aldrich, 2,4-Diamino-6-methyl-1,3,5-triazine C 4 H 7 N 5, ABCR GmbH & Co.KG, 2,4-Diamino-6-phenyl-s-triazine C 9 H 9 N 5, Agros Organics, DiethylenetriaminePenta (Methylene Phosphonic Acid)C 9 H 28 O 15 N 3 P 5, Chemos, Ethylenebis(nitrilodimethylene)tetraphosphonic Acid C 6 H 20 N 2 O 12 P 4 xh 2 O, TCI Europe, Guanidine Carbonate [H 2 NC(=NH)NH 2 ] 2 *H 2 CO 3, Aldrich Chemistry, Magnesium Hydroxide Mg(OH) 2, VWR International, Melamine C 3 H 6 N 6, Aldrich Chemistry, Nitrilotris(methylene)triphosphonic Acid N[CH 2 P(O)(OH) 2 ] 3, Aldrich Chemistry, Phytic Acid C 6 H 18 O 24 P 6, Aldrich Chemistry, Polyamide 6, EMS-GrivoryGrilon F34 Natur, Polyethylene terephthalate, Tersuisse 74A00PC92, Poly(vinylmelamine) C 5 H 7 N 5, TCI Europe, 2.2 Laboratory equipment Analytical balance,mettler Toledo AT 200 Beaker cap. 10, 20, 50, 100, 200, 500 cm 3, Crucible cap cm 3, Drying oven (model), Funnel cap. 250, 500 cm 3, Glass stirrer, 37

38 HaakePolyLab RheoDrive16, HaakeRheomix OS, Heating bath cap. 7L, ICP, PerkinElmer Optima 3000, LOI, Fire Testing Technology Apparatus, Mechanical stirrer, PCFC, FAA Micro Calorimeter, Standard laboratory glass, Technical balance, TGA, NETZSCH TG 209 F1 Iris ASC, Thermocouple, range -40~400ºC, TMP, TottoliBuchi 510, Tree-necked glass reactor cap cm Synthesis of flame retardant To evaluate the effect of acid ratios on thermal stability of FR, a following series of experiments were performed. A glass reactor with a mechanical stirrer was filled up with water and components in sets and proportions as follows: Set A: Melamine (Mel), Phytic Acid (PA) and Boric Acid (BA) (Tab 2.1). Set B: Melamine (Mel), Nitrilotris(methylene)triphosphonic Acid (NA) and Boric Acid (BA) (Tab 2.2). Set C: Melamine (Mel), Ethylenebis(nitrilodimethylene)tetraphosphonic Acid (EA) and Boric Acid (BA) (Tab 2.3). Set D: Melamine (Mel), DiethylenetriaminePenta (Methylene Phosphonic Acid) (DA) and Boric Acid (BA) (Tab 2.4). Set E: Poly(vinylmelamine) (PVM), Phytic Acid (PA) and Boric Acid (BA) (Tab 2.5). Set F: Poly(vinylmelamine) (PVM), Nitrilotris(methylene)triphosphonic Acid (NA) and Boric Acid (BA) (Tab 2.6). 38

39 Set G: 2,4-Diamino-6-phenyl-s-triazine (DPT), Nitrilotris(methylene)triphosphonic Acid (NA) and Boric Acid (BA) (Tab 2.7). Set H: 2,4-Diamino-6-methyl-1,3,5-triazine (DMT), Nitrilotris(methylene)triphosphonic Acid (NA) and Boric Acid (BA) (Tab 2.8). The syntheses were carried out at C for 60 min. Table 2.1 Amounts of melamine, boric and phytic acid used for preparation of compositions A. Set number Mel [g] BA [g] PA [g] Acid ratio [%] of Mel Molar ratio Mel: BA: PA A :100 4: 0: 1 A : : 1: 1.41 A :67 6: 2: 1 A :50 8: 4: 1 A : : 8.1: 1 A : : 2267: 1 A :0 1: 1: 0 Table 2.2 Amounts of melamine, boric and nitrilotris(methylene)triphosphonic acid used for preparation of compositions B. Set number Mel [g] BA [g] NA [g] Acid ratio [%] of Mel Molar ratio Mel: BA: NA B :100 2: 0: 1 B : : 1: 2.82 B :67 3: 1: 1 B :50 4: 2: 1 B : : 4.06: 1 B : : 11.36: 1 39

40 Table 2.3 Amounts of melamine, boric and ethylenebis(nitrilodimethylene)tetraphosphonic acid used for preparation of compositions C.. Set number Mel [g] BA [g] EA [g] Acid ratio [%] of Mel Molar ratio Mel: BA: EA C :100 2,67: 0: 1 C : : 1: 2.12 C : : 1.37: 1 C : : 2.66: 1 C :33 8: 5.4: 1 C : : 15.13: 1 Table 2.4 Amounts of melamine, boric and diethylenetriaminepenta (methylene phosphonic acid) used for preparation of compositions D. Set number Mel [g] BA [g] DA [g] Acid ratio [%] of Mel Molar ratio Mel: BA: DA D : : 0: 1 D : : 1: 3.4 D :67 3: 1: 1.2 D :50 3.3: 1.6: 1 D :33 5: 3.4: 1 D : : 9.45: 1 Table 2.5 Amounts of poly(vinylmelamine), boric and phytic acid used for preparation of compositions E. Set number PVM [g] BA [g] PA [g] Acid ratio [%] of PVM Molar ratio PVM: BA: PA E :100 6: 0: 1 E : : 1.32: 1 E :50 12: 4: 1 E :25 24: 12: 1 E :0 1.5: 1: 0 Table 2.6. Amounts of poly(vinylmelamine), boric and nitrilotris(methylne)triphosphonic acid used for preparation of compositions F. Set number PVM [g] BA [g] NA [g] Acid ratio [%] of PVM Molar ratio PVM: BA: NA F :100 3: 0: 1 F :75 6: 1: 1.5 F :50 6: 2: 1 F : : 5.88: 1 40

41 Table 2.7 Amounts of 2,4-diamino-6-phenyl-s-triazine, boric and nitrilotris(methylne)triphosphonicacid used for preparation of compositions G. Set number DPT [g] BA [g] NA [g] Acid ratio [%] of DPT Molar ratio DPT: BA: NA G :100 3: 0: 1 G :75 6: 1: 1.5 G : : 2: 1 G : : 5.91: 1 G :0 1.5: 1: 0 Table 2.8 Amounts of 2,4-diamino-6-methyl-1,3,5-triazine, boric and nitrilotris(methylene)triphosphonicacid used for preparation of compositions H. Set number DMT [g] BA [g] NA [g] Acid ratio [%] of DMT Molar ratio DMT: BA: NA H :100 3: 0: 1 H : : 1: 1.46 H :50 6: 2: 1 H :25 12: 6: 1 H :0 1.5: 1: 0 All mixtures obtained after reactions were acidic and the additional neutralization was required. The mixtures were divided in four approximately equal samples and neutralized with: 1. guanidine carbonate, 2. 10% water solution of ammonia, 3. magnesium hydroxide, 4. aluminium hydroxide. The final suspensions were evaporated to remove volatile components and to get powders. The quality of the powders was evaluated by the methods described in points

42 2. 4 Evaluation of thermal stability Total melting point Total Melting Point (TMP) test was conducted using TottoliBuchi 510 Aparatus. Approximately 5mg samples of FR were placed in a thin glass tube and inserted into an oil bath. Heating was continued until melting or decomposition points of flame retardant compositions could be observed. Picture 2.1 Buchi 510 Melting Point Apparatus. 1 Thermometer, 2 Heated oil bath, 3 Magnifying glass, 4 Temperature control, 5 Heating speed. 42

43 Thermogravimetric analysiss Thermogravimetric analysis (TGA) was conductedd using NETZSCH TG 209 F1 Iris ASC Apparatus. The samples of powders (3-5 mg) were placed into a porcelain crucible and loss in weight with increasing in temperaturee was determined. The heating program was set to measure samples in the range of 30 C C using the dynamic heating. The heating rate was 10 C/ /min and the carrier gas flow 50 ml/min of nitrogen. Picture 2.2 NETZSCH TG 209 F1 Iris ASC Apparatus. 1 Robot arm, 2 Auto-sampler, 3 Furnace. 43

44 2.5 Rheologicall influencee effect off flame retardant on o PA6 and PET Kneadling test Kneading test was conducted using Thermo Elektron Corporationn Set. Haake PolyLab RheoDrive16 and Haake RheomixOS weree used to investigate thee influence of FR addition on temperature and shear stability, melt viscosityy of either PA6 or PET. The samples consisted of 60 g of polymer and 5% (3,17g) addition of FR. They were kept for 12 min in a heated chamber (225 C for PA6 and 245 CC for PET) equipped with rotors having the speed of 1000 rpm. Picture 2.3 Haake PolyLab RheoDrive166 with Haake Rheomix OS. 1 Heated block, 2 Rotor, 3 Block closure. 44

45 2..6 Flammability properties Pyrolysis Combustion Flow Calorimeter Pyrolysis Combustion Flow Calorimeterr (PCFC) test was conducted using FAA Micro Calorimeter. The samples, approximately 5mg of o polymerr with 5% or 10% addition of FR, were ested to investigate the influencee of FR onn total heatt release (THR) and heat release rate (HRR). Conditions applied for measurements were following: atmosphere of 80% nitrogen and 20% oxygen, pyrolizerr heated from 75 C with heating rate 1 C/s to t 750 C, combustor temperature to t 900 C. Picture 2.4 FAA Micro Calorimeter. 1 Combustor, 2 Pyrolyser, 3 Sample holder. 45

46 2.6.2 Limited Oxygen Index Limited Oxygen Index (LOI)( test was conducted using Oxygen Indexx Fire Testing Technology Apparatus. The samples consisting of PA6 with either 5% or 10% addition of FR were tested in verticall burning test with ignition time of 5 seconds. The balk specimen size for the LOI measurement was 80x5x2mm. Picture 2.5 Fire Testing Technology Apparatus. 1 Glass cylinder, 2 Sample holder, 3 Source of ignition, 4 Oxygen valve, 5 LOI index, 6 Nitrogen valve. 46

47 2..7 Qualitative Analysis Picture 2.7 Perkin Elmer Optima 3000 Apparatus. 1 Robot arm, 2 Plasma chamber, 3 Auto-sampler, 4 Pomp Nitrogen Conten Analysiss Nitrogen content analyses were performed by Kjeldahl method. The samples of the powders (250 mg) were heated withh 10 ml 98% % H 2 SO 4 and a 5g Kjeldahl tablet withoutt Hg and Se, in a Büchi425 digester unit, until the color of solution was changed to green. Thee final solutions were treated t withh NaOH (in pellets) to become basic and distilled in a Büchi distillation unit into 50 ml H 3 BO 3 (4g// L). The solution was titrated with 0.5 MHCl Phosphor, Boron, Magnesium Content Analysiss Phosphors, Boron, Magnesium contentt analysis were performed by using Inductively Coupled Plasma (ICP). 200 mg sample weree added to 3 ml HNO 3 and 1 ml H 2 O 2 and heated in the microwave at 500W for 10 min. m The solution was diluted to 50 ml with water and measured byy ICP, Perkin Elmer Optima

48 48

49 3. RESULTS AND DISCUSION PA6 is an important engineering resin manufactured in large quantities worldwide due to its excellent mechanical properties, good wear resistance, electricity and oil proof performance. But like most polymers, original PA6 is flammable with LOI of only 23, thus restricting its application in some important fields, particularly in electrical industries for various parts such as clip fasteners, switch components, wire ties, electrical connectors, terminal blocks, etc., therefore, flame retardant PA6 is badly in need. In recent years, traditional halogen flame retardants have been challenged as the results of the ecological problems, and halogen-free products are playing more and more important roles [58]. 3.1 Evaluation of thermal stability by total melting point (TMP) and thermogravimetric analysis Synthesis of flame retardants were performed by using components and proportion presented in (Tab ). Then thermal resistance of compositions obtained after synthesis have been assessed by the methods described in point and Results of TMP and TGA analyses are presented in (Tab ) and TGA analysis on (Fig ). 49

50 Table 3.1 Thermal stability of composition: melamine, phytic (PA) and boric (BA) acid measured by TMP and TGA. Set Acid relation TGA Neutralizer Total Malting Point [ºC] A PA: BA Onset [ºC] Guanidine Carbonate 100% : 0% Intumescent effect at ,6 A1 Ammonia Hydroxide 100% : 0% Visual decomposition at ,7 Magnesium Hydroxide 100% : 0% Visual decomposition at ,7 Aluminium Trihydroxide 100% : 0% Visual decomposition at 225 Gradually decay Guanidine Carbonate 85% : 15% Intumescent effect at ,7 A2 Ammonia Hydroxide 85% : 15% Visual decomposition at ,1 Magnesium Hydroxide 85% : 15% Visual decomposition at ,0 Aluminium Trihydroxide 85% : 15% Visual decomposition at 170 Gradually decay Guanidine Carbonate 67% : 33% Intumescent effect at 130 Gradually decay A3 Ammonia Hydroxide 67% : 33% Visual decomposition at ,8 Magnesium Hydroxide 67% : 33% Visual decomposition at Aluminium Trihydroxide 67% : 33% Visual decomposition at 170 Gradually decay Guanidine Carbonate 50% : 50% Intumescent effect at ,0 A4 Ammonia Hydroxide 50% : 50% Visual decomposition at ,5 Magnesium Hydroxide 50% : 50% Visual decomposition at ,2 Aluminium Trihydroxide 50% : 50% Visual decomposition at 245 Gradually decay Guanidine Carbonate 33% : 67% Visual decomposition at ,4 A5 Ammonia Hydroxide 33% : 67% Visual decomposition at ,3 Magnesium Hydroxide 33% : 67% Visual decomposition at ,4 Aluminium Trihydroxide 33% : 67% Visual decomposition at 275 Gradually decay Guanidine Carbonate 15% : 85% Visual decomposition at ,9 A6 Ammonia Hydroxide 15% : 85% Visual decomposition at ,1 Magnesium Hydroxide 15% : 85% Visual decomposition at ,6 Aluminium Trihydroxide 15% : 85% Visual decomposition at 275 Gradually decay A7 0% : 100% No visual decomposition until ,2 According to thermal resistance (TGA) and visual evaluation (TMP) results it was observed that a lower concentration of phytic acid increased the thermal stability of flame retardant. Due of a large number of obtained compositions and limited availability of the measuring apparatus and the time needed to perform the analyses maximum of three from the most thermally stable compositions (one per each neutralizer) were selected for further test: 1. Composition from set A5 neutralized with guanidine carbonate with visual decomposition point at 275 C and TGA onset at 275,4 C. 2. Composition from set A6 neutralized with 10% water solution of ammonia with visual decomposition point at 280 C and TGA onset at 270,2 C. 3. Composition from set A6 neutralized with magnesium hydroxide with visual decomposition point at 290 C and TGA onset at 269,6 C. Aluminium trihydroxide was also used as a neutralizer but the flame retardant obtained in this way do not provide the thermal conditions required for the spinning 50

51 process of PA6 and PET. Because of that reason aluminium trihydroxide was omitted in further experiments. Table 3.2 Thermal stability of composition: melamine, nitrilotris(methylene)triphosphonic (NA) and boric (BA) acid measured by TMP and TGA. Set A B1 B2 B3 B4 B5 B6 Neutralizer Acid relation TGA Total Malting Point [ºC] NA: BA Onset [ºC] Guanidine Carbonate 100% : 0% Intumescent effect at 170 Gradually decay Ammonia Hydroxide 100% : 0% Visual decomposition at 230 Gradually decay Magnesium Hydroxide 100% : 0% No visual decomposition until ,4 Guanidine Carbonate 85% : 15% Intumescent effect at ,3 Ammonia Hydroxide 85% : 15% Visual decomposition at ,7 Magnesium Hydroxide 85% : 15% No visual decomposition until ,5 Guanidine Carbonate 67% : 33% Intumescent effect at ,9 Ammonia Hydroxide 67% : 33% No visual decomposition until ,7 Magnesium Hydroxide 67% : 33% No visual decomposition until ,7 Guanidine Carbonate 50% : 50% Intumescent effect at ,1 Ammonia Hydroxide 50% : 50% Visual decomposition at ,3 Magnesium Hydroxide 50% : 50% No visual decomposition until ,9 Guanidine Carbonate 33% : 67% No visual decomposition until ,0 Ammonia Hydroxide 33% : 67% No visual decomposition until ,7 Magnesium Hydroxide 33% : 67% No visual decomposition until ,9 Guanidine Carbonate 15% : 85% No visual decomposition until ,0 Ammonia Hydroxide 15% : 85% No visual decomposition until ,3 Magnesium Hydroxide 15% : 85% No visual decomposition until ,0 Thermal resistance (TGA) and visual evaluation (TMP) results indicated that a middle concentration of nitrilotris(methylene)triphosphonic acid provided better thermal stability of flame retardant. Three from the most thermally stable compositions (one per each neutralizer) were selected for further test: 1. Composition from set B5 neutralized with guanidine carbonate with no visual observation of decomposition until 310 C and TGA onset at 274 C. 2. Composition from set B3 neutralized with 10% water solution of ammonia with no visual observation of decomposition until 310 C and TGA onset at 271,7 C. 3. Composition from set B6 neutralized with magnesium hydroxide with no visual observation of decomposition until 310 C and TGA onset at 276 C. 51

52 Table 3.3 Thermal stability of composition: melamine, ethylenebis(nitrilodimethylene)tetraphosphonic (EA) and boric (BA) acid measured by TMP and TGA. Set A C1 C2 C3 C4 C5 C6 Neutralizer Acid relation TGA Total Malting Point [ºC] EA: BA Onset [ºC] Guanidine Carbonate 100% : 0% Visual decomposition at ,1 Ammonia Hydroxide 100% : 0% Intumescent effect at 225 Gradually decay Magnesium Hydroxide 100% : 0% No visual decomposition until ,9 Guanidine Carbonate 85% : 15% Intumescent effect at ,3 Ammonia Hydroxide 85% : 15% Intumescent effect at 252 Gradually decay Magnesium Hydroxide 85% : 15% Visual decomposition at ,3 Guanidine Carbonate 67% : 33% No visual decomposition until ,7 Ammonia Hydroxide 67% : 33% Intumescent effect at ,3 Magnesium Hydroxide 67% : 33% No visual decomposition until ,4 Guanidine Carbonate 50% : 50% Intumescent effect at ,9 Ammonia Hydroxide 50% : 50% Intumescent effect at ,8 Magnesium Hydroxide 50% : 50% No visual decomposition until ,9 Guanidine Carbonate 33% : 67% Intumescent effect at ,2 Ammonia Hydroxide 33% : 67% Visual decomposition at ,1 Magnesium Hydroxide 33% : 67% No visual decomposition until ,1 Guanidine Carbonate 15% : 85% No visual decomposition until ,9 Ammonia Hydroxide 15% : 85% No visual decomposition until ,6 Magnesium Hydroxide 15% : 85% No visual decomposition until ,1 From TMP test results that some of the compositions have very desirable intumescent effect in temperature higher than 280 C. Therefore, basing on thermal resistance (TGA) and visual evaluation (TMP) parameters three compositions with the highest possible concentration of ethylenobis(nitrilodimethylene)tetraphosphonic acid and sufficient thermal stability were selected to further exploration: 1. Composition from set C2 neutralized with guanidine carbonate with strong intumescent effect at 285 C and TGA onset at 268,3 C. 2. Composition from set C4 neutralized with guanidine carbonate with strong intumescent effect at 289 C and TGA onset at 266,9 C. 3. Composition from set C4 neutralized with magnesium hydroxide with no visual observation of decomposition until 310 C and TGA onset at 277,9 C. 52

53 Table 3.4 Thermal stability of composition: melamine, diethylenetriaminepenta(metylenephosphonic) (DA) and boric (BA) acid measured by TMP and TGA. Set A D1 D2 D3 D4 D5 D6 Neutralizer Acid relation TGA Total Malting Point [ºC] DA: BA Onset [ºC] Guanidine Carbonate 100% : 0% Do not performed Do not performed Ammonia Hydroxide 100% : 0% Do not performed Do not performed Magnesium Hydroxide 100% : 0% Visual decomposition at 285 Gradually decay Guanidine Carbonate 85% : 15% Do not performed Do not performed Ammonia Hydroxide 85% : 15% Do not performed Do not performed Magnesium Hydroxide 85% : 15% Visual decomposition at 285 Gradually decay Guanidine Carbonate 67% : 33% Intumescent effect at ,0 Ammonia Hydroxide 67% : 33% Visual decomposition at Magnesium Hydroxide 67% : 33% Visual decomposition at 295 Gradually decay Guanidine Carbonate 50% : 50% Intumescent effect at ,9 Ammonia Hydroxide 50% : 50% Visual decomposition at ,7 Magnesium Hydroxide 50% : 50% Visual decomposition at ,5 Guanidine Carbonate 33% : 67% Intumescent effect at ,9 Ammonia Hydroxide 33% : 67% Visual decomposition at ,6 Magnesium Hydroxide 33% : 67% No visual decomposition until ,8 Guanidine Carbonate 15% : 85% Intumescent effect at ,2 Ammonia Hydroxide 15% : 85% Visual decomposition at ,6 Magnesium Hydroxide 15% : 85% No visual decomposition until ,7 The flame retardants which contained diethylenetriaminepenta(methylenephosphonic acid) in structure were highly hygroscopic. For that reason samples with the highest (DA) acid concentration could not be evaporated completely and they had consistency of wax. Thermal resistance (TGA) and visual evaluation (TMP) results led to the conclusion that FR did not provide the thermal conditions required for the spinning process of PA6 and PET. For that reason none of the compositions were included for further tests. 53

54 Table 3.5 Thermal stability of composition: poly(vinylmelamine), phytic (PA) and boric (BA) acid measured by TMP and TGA. Set A E1 E2 E3 E4 E5 Neutralizer Acid relation TGA Total Malting Point [ºC] PA: BA Onset [ºC] Guanidine Carbonate 100% : 0% Do not performed Do not performed Ammonia Hydroxide 100% : 0% Do not performed Do not performed Magnesium Hydroxide 100% : 0% Do not performed Do not performed Guanidine Carbonate 75% : 25% Do not performed Do not performed Ammonia Hydroxide 75% : 25% Do not performed Do not performed Magnesium Hydroxide 75% : 25% Do not performed Do not performed Guanidine Carbonate 50% : 50% Visual decomposition at 280 Gradually decay Ammonia Hydroxide 50% : 50% Visual decomposition at 240 Gradually decay Magnesium Hydroxide 50% : 50% Visual decomposition at ,1 Guanidine Carbonate 25% : 75% Visual decomposition at 285 Gradually decay Ammonia Hydroxide 25% : 75% Visual decomposition at 260 Gradually decay Magnesium Hydroxide 25% : 75% Visual decomposition at ,3 Guanidine Carbonate 0% : 100% No visual decomposition until ,0 Ammonia Hydroxide 0% : 100% No visual decomposition until ,2 Magnesium Hydroxide 0% : 100% No visual decomposition until ,9 It was found that the ratio higher than 50% of phytic acid (PA) led particles to adhere to each other what resulted in the conglomeration of all particles. For that reason it was impossible to obtain a homogeneous mixture. According to thermal resistance (TGA) and visual evaluation (TMP), the highest possible concentration of phytic acid was selected for further test: Composition from set E3, neutralized with magnesium hydroxide with no visual observation of decomposition until 310 C and TGA onset at 388,1 C. Table 3.6 Thermal stability of composition: poly(vinylmelamine), nitrilotris(methylene)triphosphonic (NA) and boric (BA) acid measured by TMP and TGA. Set A F1 F2 F3 F4 Neutralizer Acid relation TGA Total Malting Point [ºC] NA: BA Onset [ºC] Guanidine Carbonate 100% : 0% Do not performed Do not performed Ammonia Hydroxide 100% : 0% Do not performed Do not performed Magnesium Hydroxide 100% : 0% Do not performed Do not performed Guanidine Carbonate 75% : 25% Visual decomposition at 300 Gradually decay Ammonia Hydroxide 75% : 25% Visual decomposition at 270 Gradually decay Magnesium Hydroxide 75% : 25% No visual decomposition until ,7 Guanidine Carbonate 50% : 50% No visual decomposition until 310 Gradually decay Ammonia Hydroxide 50% : 50% Visual decomposition at 285 Gradually decay Magnesium Hydroxide 50% : 50% No visual decomposition until ,2 Guanidine Carbonate 25% : 75% No visual decomposition until 310 Gradually decay Ammonia Hydroxide 25% : 75% No visual decomposition until 310 Gradually decay Magnesium Hydroxide 25% : 75% No visual decomposition until ,5 54

55 It was alsofound that the ratio higher than 75% of nitrilotris(methylene)triphosphonic acid (NA) led particles to adhere to another particles. In consequence, agglomeration of all particles was occurred. For that reason it was impossible to obtain a homogeneous mixture. According to thermal resistance (TGA) and visual evaluation (TMP), the highest possible concentration of NA in formula was selected for further test: Composition from set F2, neutralized with magnesium hydroxide with no visual observation of decomposition until 310 C and TGA onset at 352,7 C. Table 3.7 Thermal stability of composition: 2,4-diamino-6-phenyl-s-triazine, nitrilotris(methylene)triphosphonic (DPT) and boric (BA) acid measured by TMP and TGA. Set A G1 G2 G3 G4 G5 Neutralizer Acid relation TGA Total Malting Point [ºC] DPT : BA Onset [ºC] Guanidine Carbonate 100% : 0% Melting point at ,5 Ammonia Hydroxide 100% : 0% Melting point at ,7 Magnesium Hydroxide 100% : 0% No visual decomposition until ,6 Guanidine Carbonate 75% : 25% Melting point at ,2 Ammonia Hydroxide 75% : 25% Melting point at ,5 Magnesium Hydroxide 75% : 25% Melting point at ,3 Guanidine Carbonate 50% : 50% Melting point at ,8 Ammonia Hydroxide 50% : 50% Melting point at ,3 Magnesium Hydroxide 50% : 50% Melting point at ,9 Guanidine Carbonate 25% : 75% Melting point at ,6 Ammonia Hydroxide 25% : 75% Melting point at ,1 Magnesium Hydroxide 25% : 75% Melting point at ,2 Guanidine Carbonate 0% : 100% Melting point at ,4 Ammonia Hydroxide 0% : 100% Melting point at ,0 Magnesium Hydroxide 0% : 100% Melting point at ,4 Table 3.8 Thermal stability of composition: 2,4-diamino-6-methyl-1,3,5-triazine, nitrilotris(methylene)triphosphonic (DMT) and boric (BA) acid measured by TMP and TGA. Set Acid relation TGA Neutralizer Total Malting Point [ºC] A DMT : BA Onset [ºC] Guanidine Carbonate 100% : 0% Melting point at ,5 H1 Ammonia Hydroxide 100% : 0% Melting point at ,9 Magnesium Hydroxide 100% : 0% No visual decomposition until ,9 Guanidine Carbonate 75% : 25% Melting point at ,1 H2 Ammonia Hydroxide 75% : 25% Melting point at ,1 Magnesium Hydroxide 75% : 25% No visual decomposition until ,6 Guanidine Carbonate 50% : 50% Melting point at ,8 H3 Ammonia Hydroxide 50% : 50% Melting point at ,2 Magnesium Hydroxide 50% : 50% No visual decomposition until ,4 Guanidine Carbonate 25% : 75% Melting point at ,5 H4 Ammonia Hydroxide 25% : 75% Melting point at ,6 Magnesium Hydroxide 25% : 75% Visual decomposition at ,4 H5 0% : 100% Melting point at ,9 55

56 Thermal resistance (TGA) and visual evaluation (TMP) led to the conclusion that FR which from sets G and H, did notprovide the thermal conditions required for the spinning process of PA6 and PET. For that reason none of the compositions were included for further tests. Table 3.9 Compositions selected for further tests. Set Neutralizer Acid relation Total Malting Point [ºC] TGA Onset [ºC] A5 Guanidine Carbonate 33% : 67% Visual decomposition at ,4 A6 Ammonia Hydroxide 15% : 85% Visual decomposition at ,1 A6 Magnesium Hydroxide 15% : 85% Visual decomposition at ,6 B5 Guanidine Carbonate 33% : 67% No visual decomposition until ,0 B3 Ammonia Hydroxide 67% : 33% No visual decomposition until ,7 B6 Magnesium Hydroxide 15% : 85% No visual decomposition until ,0 C2 Guanidine Carbonate 85% : 15% Intumescent effect at ,3 C4 Guanidine Carbonate 50% : 50% Intumescent effect at ,9 C4 Magnesium Hydroxide 50% : 50% No visual decomposition until ,9 E3 Magnesium Hydroxide 50% : 50% No visual decomposition until ,1 F2 Magnesium Hydroxide 75% : 25% No visual decomposition until ,7 Fig. 3.1 Thermal stability of compositions from set A measured by TGA. 56

57 Fig. 3.2 Thermal stability of compositions from set B measured by TGA. Fig. 3.3 Thermal stability of compositions from set C measured by TGA. 57

58 Fig. 3.4 Thermal stability of compositions from set E measured by TGA. Fig. 3.5 Thermal stability of compositions from set F measured by TGA. 58

59 3.2 Evaluation of rheological influence of additives on PA6 and PET by thermo electron corporation set: Haake Polylab Rheodrive16 and Haake RheomixOs Flame retardants selected in chapter 3.1 are subject of further study. Compositions from (Tab 3.9) were investigated on their effect on rheological properties of PA6 and PET under processing conditions. Additives have been assessedby the methods described in point Results of this analysis are presented in (Tab 3.10). Table 3.10 Rheological influence of 5% addition of FR to PA6 and PET. 5% Addition in PA6 5% Addition in PET Set Neutralizer Acid relation [Nm] [Nm] Pure polymer 8,8 5,2 A5 Guanidine Carbonate 33% : 67% 4,1 Polymer degradation A6 Ammonia Hydroxide 15% : 85% 5,7 Polymer degradation A6 Magnesium Hydroxide 15% : 85% 5,3 Polymer degradation B5 Guanidine Carbonate 33% : 67% 5,8 Polymer degradation B3 Ammonia Hydroxide 67% : 33% 2,8 Polymer degradation B6 Magnesium Hydroxide 15% : 85% 6,2 Polymer degradation C2 Guanidine Carbonate 85% : 15% 3,8 Polymer degradation C4 Guanidine Carbonate 50% : 50% 3,2 Polymer degradation C4 Magnesium Hydroxide 50% : 50% 5,7 Polymer degradation E3 Magnesium Hydroxide 50% : 50% 8,8 Polymer degradation F2 Magnesium Hydroxide 75% : 25% 8,8 Polymer degradation It was observed that 5% addition of flame retardant (FR) to PA6, except compositions which come form set E3 and F2 both neutralized by magnesium hydroxide (MH), decreased viscosity of polymers. However the mixture saved properties of pure polymer such as the flexibility and durability. Explanation of this behaviour is facts that melamine acts as a softener in the melting process. Some interactions between melamine and polymer chains are still possible. The poly(vinylmelamine) does not show such effect and viscosity is constant. Different situation was in PET case. The polymer degraded completely during the test and it had fluid (water) consistency. Possible explanation of this behaviour is the fact that ester bonds were destructed by acids present in flame retardant structure. For this reason industrial application of flame retardants obtained during experiments to PET are pointless. Because of that flammability tests will be performed only for PA6. 59

60 For this reason industrial applicationof flame retardants obtained during experiments to PET are pointless. Because of that flammability tests will be performed only for PA Evaluation of flammability by Pyrolysis Combustion Flow Calorimeter (PCFC) And Limited Oxygen Index (LOI) Flame retardants evaluated and selected in chapter 3.1 are subject of further study. Compositions from (Tab 3.9) were investigated on their effect on flammability of PA6 and PET with 5% or 10% addition of flame retardant. Additives have been assessed by the methods described in point and Results of those analyses are presented in (Tab ) and on (Fig ). Table 3.11 Flammability of PA6 with 5% addition of FR measured by PCFC. 5% addition to PA6 THR Improvement HRR Improvement Ignition [kj/g] [%] [W/g] [%] temp. [ºC] Pure PA6 27, , ,9 A5 Guanidine Carbonate 24,2 10,7 485,0 1,98 466,9 A6 Ammonia Hydroxide 23,8 12,18 492,5 0,46 446,0 A6 Magnesium Hydroxide 24,0 11,44 484,9 1,98 465,0 B5 Guanidine carbonate 23,5 13,28 423,6 14,39 437,8 B3 Ammonia Hydroxide 23,9 11,81 455,0 8,04 426,4 B6 Magnesium Hydroxide 23,8 12,18 486,6 1,66 457,6 C2 Guanidine Carbonate 23,6 12,92 427,0 13,7 436,9 C4 Guanidine Carbonate 24,7 8,86 484,5 2,08 471,4 C4 Magnesium Hydroxide 25,1 7,38 463,1 6,41 429,0 E3 Magnesium Hydroxide 25,6 5,34 493,3 0,31 459,7 F2 Magnesium Hydroxide 25,0 7,75 476,1 3,78 459,2 60

61 Table 3.12 Flammability of PA6 with 10% addition of FR measured by PCFC. 10% addition to PA6 THR Improvement HRR Improvement Ignition [kj/g] [%] [W/g] [%] temp. [ºC] Pure PA6 27, , ,9 A5 Guanidine Carbonate 21,5 20,66 458,7 7,30 455,3 A6 Ammonia Hydroxide 22,4 17,34 462,3 6,57 448,3 A6 Magnesium Hydroxide 22,5 16,97 465,7 5,88 461,6 B5 Guanidine carbonate 22,2 18,08 414,8 16,17 435,4 B3 Ammonia Hydroxide 22,5 16,97 424,9 14,13 418,0 B6 Magnesium Hydroxide 23,1 14,76 461,8 6,67 460,0 C2 Guanidine Carbonate 23,5 13,28 389,9 21,20 423,1 C4 Guanidine Carbonate 23,7 12,55 476,0 3,80 460,6 C4 Magnesium Hydroxide 23,0 15,13 413,5 16,43 415,2 E3 Magnesium Hydroxide 23,6 12,92 404,0 18,35 455,4 F2 Magnesium Hydroxide 23,4 13,65 381,0 23,00 453, HRR [kj/g] pure PA6 5% Set A5 Guanidine Carbonate 5% Set A6 Ammonium Hydroxide Temperature [ºC] Fig. 3.6 Influence of 5% addition of composition from Set A5 and A 6 on flammability of PA6 measured by PCFC. 61

62 pure PA6 10% Set A5 Guanidine Carbonate 10% Set A6 Ammonia Hydroxide 300 HRR [kj/g] Temperature [ºC] Fig. 3.7 Influence of 10% addition of composition from Set A5 and A6 on flammability of PA6 measured by PCFC Pure PA6 5% Set B5 Guanidine Carbonate 5% Set B3 Ammonia Hydroxide 300 HRR [kj/g] Temperature [ºC] Fig. 3.8 Influence of 5% addition of composition from Set B3, B5 and B6 on flammability of PA6 measured by PCFC. 62

63 pure PA6 10% Set B5 Guanidine Carbonate 10% Set B3 Ammonia Hydroxide 300 HRR [kj/g] Temperature [ºC] Fig. 3.9 Influence of 10% addition of composition from Set B3, B5 and B6 on flammability of PA6 measured by PCFC pure PA6 5% Set C2 Guanidine Carbonate 5% Set C4 Guanidine Carbonate 300 HRR [kj/g] Temperature [ºC] Fig Influence of 5% addition of composition from Set C2, C4 and C4 on flammability of PA6 measured by PCFC. 63

64 pure PA6 10% Set C2 Guanidine Carbonate 10% Set C4 Guanidine Carbonate 300 HRR [kj/g] Temperature [ºC] Fig Influence of 10% addition of composition from Set C2, C4 and C4 on flammability of PA6 measured by PCFC pure PA6 5% Set E3 Guanidine Carbonate 5% Set F2 Magnesium Hydroxide 300 HRR [kj/g] Temperature [ºC] Fig Influence of 5% addition of composition from Set E3 and F2 on flammability of PA6 measured by PCFC. 64

65 pure PA6 10% Set E3 Magnesium Hydroxide 10% Set F2 Magnesium Mydroxide 300 HRR [kj/g] Temperature [ºC] Fig Influence of 10% addition of composition from Set E3 and F2 on flammability of PA6 measured by PCFC. According to PCFC measurement it was observed that the addition of FR to PA6 reduced heat release rate (HRR) on average by 5% for 5% addition of FR and by 12.7% for 10% addition of FR. Total heat released (THR) was reduced on average by 10.4% for 5% addition of FR and by 15.7% for 10% addition of FR. It was observed that for samples with FR, pyrolysis started earlier than for pure PA6 and ignition temperature was reduced on average by 6% in both case, which indicated interaction between PA6 and FR. 65

66 Table 3.13 Flammability of PA6 with 5% and 10% addition of FR measured by LOI. Set Pure PA6 A5 GuanidineCarbonate A6 AmmoniaHydroxide A 6 Magnesiumhydroxide B5 GuanidineCarbonate B3 AmmoniaHydroxide B 6 MagnesiumHydroxide C2 GuanidineCarbonate C4 GuanidineCarbonate C4 MagnesiumHydroxide E3 MagnesiumHydroxide F2 MagnesiumHydroxide LOI 5% Addition , 5 23, , , , 5 LOI 10% Addition ,5 23, , ,5 25,5 Ignitionn Time [s] LOI 5% Addition LOI 10% Addition pure PA Fig Influencee of 5% and 10% addition of FR on flammability of PA6. 66

67 Picture 3.1 Comparison of sampless with the highest scoree after LOI test, from left: pure PA6, PA6 with 10% addition of composition B6, C4, E3 and F22 all neutralized by Magnesium Hydroxide. Asignificant improvement of LOI index was observed for thee four compositions from Sets: B6, C4, E3 and F2 all neutralized by magnesium hydroxide. LOI was increased from 22.5 for balk of pure polymer to with 5% % addition of flame retardant and with 10% addition of flame retardant. For those flame retardant which indicatedd the best flame f extinguish properties in LOI test estimated cost of material, needed for productionn of 1kg of flame retardant. Component price per kilogram: 1. melamine 13 CHF 2. vinylmelamine 1534 CHF 3. phytic acid 2000 CHF 4. nitrilotris(methylene)triphosphonic acid 30 CHF 5. ethylenebis(nitrilodimethylene)tetraphosphonic acid 3144 CHF 6. magnesium hydroxide 13.5 CHF Composition from set B66 contains 47.5% nitrilotris(methylene)triphosphonic acid, 19.77% of magnesium hydroxide. Estimated material cost of composition is 12.8 CHF/kg. of melamine, 8.43% of boric acidd and 24.3% of 67

68 Composition from set C4 contains 38.55% of melamine, 9.45% of boric acid, 24.25% of magnesium hydroxide andd 27.75% of ethylenebis(nitrilodimethylene) tetraphosphonic acid. Estimated material cost of composition iss CHF/kg. Composition from set E3 contains 26.4% of poly(vinylmelamine), 4% of boric acid, 59% of magnesiumm hydroxide and 10.6 % of phytic acid. Estimated material cost of composition iss CHF/kg. Composition from set F2 contains 29.06% of poly(vinylmelamine), 2..21% of boric acid, 52.89% of magnesium hydroxide and 15.85% of o nitrilotris(methylene) triphosphonic acid. Estimated material cost of composition iss CHF/kg. Table3..14 Percentage contentt of N, B, P and Mg in compositions from set: B6, C4, E3, and F2 measured by ICP. Set B6 C4 E3 F2 Nitrogen [%] 29,6 25,9 18,0 14,9 Boron [%] Phosphor [%] 2,7 2,,4 1,4 6,,3 0,41 4,,7 0,35 4,,7 Magnesium [%] 13,8 13,8 17,9 22, Nitrogen [%] Phosphor [%] Boron [%] Magnesium [%] 20 [%] B6 C4 Fig Percentage content of N, B, P and F2 measured by ICP. E3 F2 Set and Mg in compositions from set:b6, C4, E3, 68