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The combustion behaviour of polymeric materials either fire retarded or not, burning in the Glow Wire and UL 94 tests, was characterised by means of thermography. It is shown that the distribution of temperatures in the gas and condensed phase of the burning specimen thus recorded, supplies fundamental complementary information for the characterisation of the combustion process.

Experimental results show, that the UL 94 classifications V0 or V1 are not in accordance with the real inflammability properties. For ignition times up to 20 s the classification is very erratic and accidental. More flammable materials may yield a better classification and vice versa. These results are explainable and confirmed by theoretical considerations.

The temperature distribution in the condensed and gas phase during combustion of polymer materials in fire tests was measured by means of thermography. It is shown that these data are very useful for mechanistic rationalization of the diagnostically poor, fail-pass rating of most of these tests. Preliminary data were obtained for polymer materials, fire retarded or not, burning in the widely used Glow Wire and UL 94 tests. It is shown that the relative fire hazard and test rating may depend strongly on the combustion parameter on which the rating is based. Furthermore, detailed data on temperature distribution are helpful in eliminating intrinsic ambiguity of the UL 94 classification in the case of fire-retarded materials burning with dripping.

The tri(o-phenylenediamine) cyclotriphosphazene (TPCTP) was synthesized using titrating technology of hexachlorocyclotriphosphazene solution and the synthesis parameters were investigated, and the structure of TPCTP was analyzed by FTIR in this paper. Using TPCTP synthesized in the work as flame retardant, the epoxy molding compound(EMC) for packaging of large-scale integrated circuits with halogen-free flame retardance was prepared. The results have shown that the flame retardance of EMC flame-retardanced by TPCTP was up to UL 94 V0 rating(1.6mm) and the oxygen index of the EMC was up to 34.5%, which indicates that TPCTP has much better flame retardance for EMC than traditional halogen flame-retardants. Meanwhile, TPCTP accelerated the curing reaction rate of EMC, which can be used for manufacturing the quick-curing EMCs or afterward-curing-free EMCs.

The objective of this research is to develop an improved polyamide 11 polymer with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering rapid manufacturing. In the present study, a nanophase was introduced into the polyamide 11 and combine with a conventional intumescent flame retardant (FR) additive via twin screw extrusion. Polyamide 11 polymer pellets were blended separately with chemically modified montmorillonite nanoclays (NCs), or carbon nanofibers (CNFs), or multi-walled carbon nanotubes (MWNTs), or nano-alumina (NA) and an intumescent FR additive to create a family of intumescent FR polyamide 11 nanocomposites. Transmission electron microscopy (TEM) analyses indicated good dispersion of individual nanoparticles and intumescent FR additives were achieved in the polymer matrix. Injection molded specimens were fabricated for physical, thermal, flammability, and mechanical properties characterization. Thermal stability of these polyamide 11 nanocomposites was examined by TGA. All systems of polyamide 11 containing nanoparticles and FR additive have higher decomposition temperatures than those compositions with solely nanoparticles or FR additive alone. None of the nanoparticles alone was able to pass UL 94 V-0 rating. Selective FR-PA11-nanoclay and FR-PA11-CNF nanocomposites passed the UL 94 V-0 requirement and suggest synergism between FR and selected nanoparticles. Some trends and relationships were observed between the results of TGA, UL 94, heat deflection temperature, and cone calorimetry.

The pyrolysis and flammability of phosphonium-modified layered silicate epoxy resin nanocomposites (EP/LS) were evaluated when LS was combined with two flame retardants, melamine borate (MB) and ammonium polyphosphate (APP), that also act via a surface protection layer. Thermogravimetry (TG), TG coupled with Fourier Transform Spectroscopy (TG-FTIR), oxygen index (LOI), UL 94 burning chamber (UL 94) and cone calorimeter were used. The glassy coating because of 10 wt % MB during combustion showed effects in the cone calorimeter test similar to nanodispersed LS, and somewhat better flame retardancy in flammability tests, such as LOI and UL 94. Adding APP to EP resulted in intumescent systems. The fire retardancy was particularly convincing when 15 wt % APP was used, especially for low external heat flux, and thus, also in flammability tests like LOI and UL 94. V0 classification is achieved when 15 wt % APP is used in EP. The flame retardancy efficiency of the protection layers formed does not increase linearly with the MB and APP concentrations used. The combination of LS with MB or APP shows antagonism; thus the performance of the combination of LS with MB or APP, respectively, was disappointing. No optimization of the carbonaceous-inorganic surface layer occurred for LS-MB. Combining LS with APP inhibited the intumescence, most probably through an increase in viscosity clearly above the value needed for intumescent behavior. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Thermal protection materials are required to protect structural components of space vehicles during the re-entry stage, missile launching systems, and solid rocket motors. Novel materials based on nanotechnolog y creating nontraditional polymers are rapidly changing the technology base for thermal protection systems. In the present study, a nanophase was introduced into the thermoplastic polyurethane elastomer via twin screw extrusion. Thermoplastic polyurethane elastomer pellets were blended separately with chemically modified montmorillonite organoclays, carbon nanofibers, or multiwall carbon nanotubes to create a family of thermoplastic polyurethane elastomer nanocomposites. Flammability properties of each family of materials were studied using UL 94. The addition of different nanoadditive to the thermoplastic polyurethane elastomer drastically changes its flammability properties, charred strength, and failure mechanism.

A series of UV-curable flame retardant resins was obtained using epoxy acrylate (EA) modified with 1-oxo-4-hydroxymethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane (PEPA). The flammability was characterized by limiting the oxygen index (LOI), UL 94 and cone calorimeter, and the thermal degradation of the flame retardant resins was studied using thermogravimetric analysis (TGA) and real time Fourier transform infrared (RTFTIR). The results indicated that the flame retardant efficiency increases and the heat release rate (HRR) decreases greatly with the content of PEPA. The TG data showed that the modified epoxy acrylates (MEAs) have lower initial decomposition temperatures and higher char residues than pure EA. The RTFTIR study indicates that the MEAs have lower thermal oxidative stability than the pure EA. Copyright © 2009 John Wiley & Sons, Ltd.

The objective of this research is to develop an improved polyamide 11 polymer with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering rapid manufacturing. In the present study, a nanophase was introduced into the polyamide 11 and combining it with a conventional intumescent flame retardant (FR) additive via twin screw extrusion. Polyamide 11 polymer pellets were mixed separately with chemically modified montmorillonite (MMT) organoclays or carbon nanofibers (CNFs) and an intumescent FR additive to create a family of intumescent FR polyamide 11 nanocomposites. Transmission electron microscopy (TEM) analyses indicated good dispersion of nanoparticles and intumescent FR additives in the polymer matrix. Injection molded specimens were fabricated for physical, thermal, and flammability measurements. Thermal stability of these intumescent FR polyamide 11 nanocomposites was examined by TGA. All systems of polyamide 11 containing nanoparticles and FR additive have higher decomposition temperatures than those compositions with solely nanoparticles or FR additive alone. For the FR-PA11-nanoclay polymers, only the formulations with 20% FR and 7.5% clay passed the UL 94 V-0 requirement. For the FR-PA11-CNF polymers, all three formulations passed UL 94 V-0 requirement. Some trends and relationships were observed between the results of cone calorimetry, and those of TGA and UL 94. Mechanical properties are compromised due to the large amount of intumescent FR additive in the PA11 polymer system.

This chapter deals with experimental methods for measuring the flammability of a material, i.e., its ease of ignition, burning intensity once ignited, propensity to spread flame over its surface and the rate at which it generates smoke and toxic products of combustion. A distinction is made between two types of experimental methods. The first type consists of tests that assess the ease of ignition of a material when exposed for a short time to a small heat source. Experimental methods of the second type measure how the material responds to a thermal exposure that is representative of pre-flashover fire conditions. Examples are given of both types of tests. The effects of test conditions and specimen details on the results and their meaning in terms of real fire performance are discussed. Challenges in assessing material flammability are identified and uses and limitations of flammability tests are reviewed. The chapter concludes with a section on future trends and recommendations for further reading.

Current polyamide 11 and 12 are lacking in fire retardancy and high strength/high heat resistance characteristics for fabricated parts that are required for performance driven applications. The introduction of selected nanoparticles such as carbon nanofibers (CNFs), combined with a conventional intumescent flame retardant (FR) additive into the polyamide 11/polyamide 12 (PA11/PA12) by melt processing conditions has resulted in a family of intumescent polyamide nanocomposites. These intumescent PA11 and PA12 nanocomposites exhibit enhanced polymer performance characteristics, i.e., fire retardancy, high strength, and high heat resistance and are expected to expand the market opportunities for resin manufacturers. The overall objective of this research is to develop improved PA11 and PA12 polymers with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering (SLS) rapid manufacturing. Arkema RILSAN® PA11 polymer was examined with CNFs and Clairant Exolit® OP 1230 intumescent FR additive. They were used to create a family of FR intumescent PA11-CNF nanocomposites. Transmission electron microscopy (TEM) was used to determine the degree of CNFs and intumescent FR additive dispersion in PA11. Injection molded specimens were fabricated for material properties measurements. Thermal stability of these polymer nanocomposites (PNs) was examined by TGA. Flammability and thermal properties of these PNs were obtained using the cone calorimeter, UL 94 test method, and heat deflection temperature.

Sealed for life, closed loop, liquid cooling units are the next step in the evolution of chip cooling for desktop computers. This application requires that sufficient coolant fluid be circulating through the unit over its entire life span. Evaporative losses will account for the majority of fluid loss over time. The ideal tubing solution needs to be flexible, nonflammable, and have a permeation rate that will ensure a sufficient fluid level for the target life of the computer. The development of a tubing solution has led to the use of fluorinated ethylene propylene, FEP, for the tubing material. The unique molecular properties of this copolymer have proven capable of providing the high level of water permeation resistance required for sealed cooling units. This tubing has been validated for providing the low level of evaporative coolant loss necessary to support a minimum 7 year system life. FEP is rated as nonflammable (UL 94 V-0) and has a limiting oxygen index greater than 95. The high strength bonds in the FEP molecule also give it excellent chemical, UV, and ozone resistance

The present work is a further development of a study already started on modified epoxy/polyester systems /1/. In previous studies, attempts to incorporate covalently bonded phosphorous atoms in epoxy resins were carried out in our laboratory. Neat panels and glass-fibre (GF) reinforced composites were prepared using halogen free flame-retardant (FR) additives. These materials were tested on a cone calorimeter apparatus in order to evaluate the heat release rate (HRR) and the ignition time values for each FR formulation. LOI and UL94 tests were carried out. In the present paper, red phosphorous (Red P) together with aluminium oxide trihydrate (ATH) and glass fibre (GF) was found to be a good substitutive formulation to replace halogen based FR-additives.

Solid super acid (SSA) as a kind of green catalyst was introduced into conventional intumescent flame retardant (IFR)/ethylene-vinyl acetate (EVA) composites to increase their flame retardant efficiency. The IFR used was a combination of ammonium polyphosphate coated by melamine resin (MAPP) and pentaerythritol (PER) with weight ratio at 3 : 1. TGA results showed that the SSA promoted the reaction between MAPP and PER. The thermal degradation temperature of the IFR/EVA composites with 1.5 wt% SSA was significantly increased by 95 °C compared to that of IFR/EVA. The UL 94 V-0 rating can be achieved for EVA composites with 13 wt% total amount of IFR and SSA, while the EVA composites with individual 13 wt% IFR only passed the UL-94 V-2 rating. The char residues at 800 °C of SSA/IFR/EVA composites were 5.8 wt%, which was higher than 2.4 wt% of IFR/EVA composites. Many carbon microspheres were observed by SEM which were deposited in the char matrix after the cone calorimeter test. These carbon microspheres had better graphite structure, thus the char was strengthened and could resist more heat and gas flow erosion. The synergistic effect between the gas phase and condensed phase was considered the main factor for the increase of flame retardant properties.

Economical manufacturing methods of mass production and improvements to the properties of finished products have in many applications greatly helped to replace traditional materials, such as metals or wood, with plastics and rubbers. In particular, polypropylene (PP) is the fastest growing commodity plastic world-wide. It has found its place in many sectors such as building, transportation (automotive, railways, etc.), electrical engineering (electrical/household appliances, housings, etc.) or paper industry.

Applications of polyolefinic materials (transports, electrical cables and wires, upholstered furniture, synthetic fibers) require fire retardant (FR) properties using low additives content (≤ 30 wt. % loading) to preserve the original mechanical properties of the materials.

Cast PA6 (magnesium–polyamide 6 (MgPA6)) compounds produced using a magnesium catalysis are presently replacing other polyamides in semi-finished engineering products. Because of this increased use, the flammability of MgPA6 containing montmorillonite, graphite, carbon black, and a plasticizer is investigated. In these studies, we observed that the presence of montmorillonite deteriorates rather than improves the flame-retardant properties of MgPA6. We also noted that the presence of a plasticizer enhances the dripping tendency and consequently the burning rate of PA6 in the UL 94 Test for Flammability of Plastic Materials. In addition, the presence of carbon black reduces the fire performance of the resin while graphite improves the UL 94 classification of PA6 to a V-2.

Iminophosphorane derivatives of s-triazine and tri-s-triazine, C3N3(NPCl3)3 (1), [H2C3N3NH2(NPPh3)2]Br2 (2), [HC3N3NH2(NPPh3)2]Br (3), C6N7(NPCl3)3 (5), [HC6N7(NPCl3)3]Cl (6) were obtained by the Kirsanov reaction of melamine (1–3) and melem (5 and 6) with halogenated phosphorus compounds. The products were characterized by FTIR and solution NMR spectroscopy as well as by single-crystal X-ray diffraction. Additionally, in order to investigate the electron density distribution in the s-triazine or s-heptazine systems combined with the phosphinimine group, and to understand the influence of protonation on the triazine and heptazine moieties, quantum chemical analyses of compounds 2, 3, 5 and 6 were performed. Furthermore, by reaction of 5 with phenol the compound C6N7(NP(OPh)3)3 (7) was obtained. Its potential application as a flame retardant was examined by the UL 94 flammability test.

The combustion performance of polyamide 6,6 (PA-6,6) can be improved by the addition of red phosphorus provided it is intermolecularly cross-linked upon irradiation with 60 Co-γ-rays in the presence of triallyl cyanurate (TAC). At a content of 5 wt.-% the latter promotes cross-linking, both in the presence and absence of O 2 , by a factor of about 100. From a variety of combustion tests with samples containing red phosphorus and having been γ-irradiated in the presence of TAC it turned out that an improved fire resistance of PA-6,6 is achieved if the red phosphorus content is at least 7 wt.-%. In this case test samples were self-extinguishing and the UL 94 rating corresponded to V-0. IR analysis of the solid residue brought about evidence for the reaction of red phosphorus with the polymer.

Flame retardant formulations for polypropylene are described that comprise a heat-stable phosphonium bromide or phosphine oxide, containing cyanoethyl substituents, in combination with ammonium polyphosphate. At additive levels of (20–30)%, flame-retarded polypropylene, with an Underwriters' Laboratories UL 94 V-0 rating is obtained with little effect on thermal and mechanical properties of the polymer. A characteristic property of this flame retardant mixture is low smoke generation during burning. Mechanism studies indicate that the organophosphorus component alone acts as an inhibitor in the gas phase, whereas the ammonium polyphosphate alone acts in the condensed phase. The synergistic effect observed by the combination of these two components is due to the formation of a phosphorus-rich char which forms an insulating layer.

Five different burning tests were employed to characterize copper-clad laminates. An evaluation of the methods showed that the UL 94 vertical burning test and the needle-flame test were most difficult to pass. The glow-wire test appeared to be too insensitive to be of any practical importance. Diagrams depicting burning times versus ignition times were found to be very useful in the evaluation of the burning characteristics of laminates as well as components. Nine capacitors were investigated. It was found that smaller capacitors were more susceptible to fire than larger ones, but on the other hand they exhibited relatively short maximum burning times. The effect of ageing on flammability was evaluated for eight laminates designed for printed circuit boards. A detailed analysis of burning times showed that there was no ageing effect which was common to all materials, but on the other hand it was quite clear that ageing affected different laminates in different ways.

In recent years, natural fiber-reinforced composites are finding new applications in many sectors as they can yield economic, environmental and social benefits. In certain industries, such as building and transport, reduced material flammability is a key requirement. The aim of this paper is to examine, flammability property on Naturally Woven coconut tree leaf sheath (CLS) reinforced Phenol Formaldehyde (PF) composites. CLS composite were prepared in both treated and untreated forms with volume fraction of 60% of sheath and 40% of Phenol Formaldehyde resin. CLS were chemically treated using 5% of NaOH and composites plates were prepared by using a hydraulic hot press at 1400C. Flammability of these composites was evaluated using Underwriters Laboratory test (UL 94) and limiting oxygen index (LOI). The UL flammability tests include a standard burning test applied to vertical (UL 94 V) and horizontal test (UL 94HB) bars from which a general flammability rating is derived. In treated composites, the mass loss rate and flame propagation rate of treated composites has been decreased and resistances to flame has been increased and it is proved in both UL 94 V and UL 94HB tests. And in Limiting oxygen index test, alkali treated composites requires more oxygen than untreated composite material to burn. The result obtained revealed that the alkaline treated CLS fiber with PF resin has more compatibility. Hence treatment of CLS fibers will improve the flammability of the composite material indicating that, materials have promising applications in construction and decorative purposes.

Solid additives are commonly used in manufacturing flexible polyurethane foams (FPUFs) to incorporate novel functionality for various application purposes. However, the viscosity change as a result of solid addition in the FPUF formulation can adversely alter the physical and mechanical properties of foam materials. Here, we report a shear-responsive internal network based on –P–N–H⋯O– interfacial hydrogen bonds between the polyether–polyol chain and a solid flame-retardant (FR) of 6,6′-(ethane-1,2-diylbis-(azanediyl))-bis-9,10-dihydro-9-oxa-phosphaphenanthrene-10-oxide (EDAB-DOPO) and its utilization in FPUFs. This interfacial interaction can stabilize the FR-polyol suspensions against sedimentation and it can be destroyed by shear force before foaming to control the fluid viscosity and thus control the physical–mechanical properties of FPUFs. The excellent dispersibility of FR particles from suspensions is well preserved in FPUFs by the optimized processes, which significantly enhances the flame retardancy of FPUFs with low FR content to achieve a HF1 rating in UL 94 test. The design of a shear-responsive internal network between solid additives and a polymer matrix provides a simple and practical method for producing functional foam composites.

The role of various additives (emulsifier, anti-dripping agent) and formulation procedures (pre-dispersion of solid additives in polyol via milling) which influence the flame retardancy of 6,6′-[ethan-1,2-diylbis(azandiyl)]bis(6H-dibenzo[c,e][1,2]oxaphosphin-6-oxid) (EDA-DOPO) containing flexible polyurethane foams has been investigated in this work. For comparison, the flame retardancy of two additional structurally-analogous bridged 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based compounds, i.e., ethanolamine-DOPO (ETA-DOPO) and ethylene glycol-DOPO (EG-DOPO) were also evaluated together with EDA-DOPO in flexible PU foams of various formulations. The flame retardancy of these three bridged-DOPO compounds depends on the type of PU formulation. For certain PU formulations containing EDA-DOPO, lower fire performance was observed. Addition of emulsifier and polytetrafluoroethylene (PTFE) to these PU formulations influenced positively the flame retardancy of EDA-DOPO/PU foams. In addition, dispersion of EDA-DOPO and PTFE via milling in polyol improved the flame retardancy of the PU foams. Mechanistic studies performed using a microscale combustion calorimeter (MCC) and its coupling to FTIR showed no difference in the combustion efficiency of the bridged-DOPO compounds in PU foams. From MCC experiments it can be concluded that these bridged-DOPO compounds and their decomposition products may work primarily in the gas phase as flame inhibitors. The physiochemical behavior of additives in PU formulation responsible for the improvement in the flame retardancy of PU foams was further investigated by studying the dripping behavior of the PU foams in the UL 94 HB test. A high-speed camera was used to study the dripping behavior in the UL 94 HB test and results indicate a considerable reduction of the total number of melt drips and flaming drips for the flame retardant formulations. This reduction in melt drips and flaming drips during the UL 94 HB tests help PU foams achieve higher fire classification.

Addition of natural clay materials in intumescent polypropylene-based formulations (additive: ammonium polyphosphate and pentaerythritol) leads either to a decrease or to an increase of their fire retardant performances versus the chemical or the physical characteristics of the clay materials. A study of the factors affecting these performances has been carried out using linear and principal components analysis. This analysis shows that the results of the evaluation tests (LOI and UL 94) are affected in different ways by the adduct of the different clay material and that an increase in the LOI is not necessarily related to an increase in the UL 94 classification. LOI values are improved by the presence of the montmorillonite and of illite clay minerals which may react with acidic phosphate to form active carbonization catelysts, in addition, the results of the LOI test are improved by the presence of quartz and other foreign minerals in the clay materials. This study discusses the part played by the different constitutive minerals in the formation of defects in the polymer chain during the mixing process. It is proposed that the presence of these defects leads to a change in fire retardant performance.