Non-halogenated Flame Retardants Research Articles

Effect of gamma irradiation on linear low density polyethylene/magnesium hydroxide/sepiolite composite

Radiation crosslinking is generally used to improve the thermo-mechanical properties of the composites. A study has been carried out to investigate the effect of gamma radiation on the thermo-mechanical properties of linear low density polyethylene containing magnesium hydroxide (MH) and sepiolite (SP) as non-halogenated flame retardant additives. The developed composites are irradiated at different doses upto maximum of 150 kGy. Infrared spectra of the irradiated composites reveal the reduction in the intensity of O–H band with increase in the absorbed doses, thus indicates a distinct structural change in MH at higher doses. The thermogravimetric analysis results of unirradiated and composites irradiated at low doses (≤75 kGy) show two steps weight loss, which is changed to single step at higher doses with lower thermal stability. The melting temperature ( T m) and crystallization temperature ( T c) of irradiated composites are lowered with irradiation whereas Vicat softening temperature (VST) is increased. The increasing trend in gel content with increase in the absorbed dose confirms the presence of crosslinked network. The mechanical properties, results show significant improvement in the modulus of irradiated composites. The results also confirm that MH gradually loses its OH functionality with irradiation.

Preparation and properties of environmental friendly nonhalogen flame retardant melamine cyanurate/nylon 66 composites

AbstractMelamine cyanurate (MCA) was utilized as an environmental friendly additive to prepare the nonhalogen flame retardant MCA/Nylon 66 composites by melt blending technique. Because of the strong hydrogen bond interactions and fine interfacial compatibility between MCA and Nylon 66, the resultant even dispersion of MCA filler in polymer matrix leads to the better toughness and strength of MCA/Nylon 66 composites than those of neat Nylon 66. Both Nylon 66 and MCA/Nylon 66 composites exhibit similar α‐crystalline structure, but the presence of MCA influences the distribution of α1 and α2 crystalline phases in Nylon 66 by inducing its hydrogen‐bonded sheet separation. Moreover, the blending of MCA and Nylon 66 increases the crystallization temperature and exothermicity but decreases the thermal stability of Nylon 66 and accelerates the degradation of MCA. The MCA/Nylon 66 composites show better flame retardancy at intermediate MCA contents of 10 and 15 wt %. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The non-halogen flame retardant epoxy resin based on a novel compound with phosphaphenanthrene and cyclotriphosphazene double functional groups

A novel flame retardant additive hexa-(phosphaphenanthrene -hydroxyl-methyl-phenoxyl)-cyclotriphosphazene (HAP–DOPO) with phosphazene and phosphaphenanthrene double functional groups has been synthesized from hexa-chloro-cyclotriphosphazene, 4-hydroxy-benzaldehyde and 9,10-dihydro-9-oxa-10- phosphaphenanthrene 10-oxide(DOPO). The structure of HAP–DOPO was characterized by Fourier transformed infrared (FT-IR) spectroscopy and 1H nuclear magnetic resonance ( 1H NMR) and 31P nuclear magnetic resonance ( 31P NMR). The additive HAP–DOPO was blended into diglycidyl ether of bisphenol-A (DGEBA) to prepare flame retardant epoxy resins. The flame retardant properties and thermal properties of the epoxy resins cured by 4, 4′-Diamino-diphenyl sulfone (DDS) were investigated from the differential scanning calorimeter (DSC), the thermogravimetric analysis (TGA), UL94 test, the limiting oxygen index (LOI) test and Cone calorimeter. Compared to traditional DOPO–DGEBA and ODOPB–DGEBA thermosets, the HAP–DOPO/DGEBA thermosets have higher T gs at the same UL94 V-0 flammability rating for their higher crosslinking density and have higher char yield and lower pk-HRR at same 1.2 wt.% phosphorus content which confirm that HAP–DOPO has higher flame retardant efficiency on thermosets. The scanning electron microscopy (SEM) results shows that HAP–DOPO in DGEBA/DDS system obviously accelerate formation of the sealing, stronger and phosphorus-rich char layer to improve flame retardant properties of matrix during combustion.

Preparation of novel non-halogen flame-retardant papers.

Halogen-containing flame-retardant paper products have both good efficacies and cost competitiveness. However, facing increasingly stringent environmental protection and safety requirements, these products could become a liability in service. Developing effective and cost-competitive non-halogen flame retardant paper products has thus become a goal of product development by the paper industry. In this study, we investigated the application of certain papermaking functional additives, particularly minerals, to develop fire-resistant agents or flame-retardant papers that are not liable to become soggy when exposed to moisture in the atmosphere. Five inorganic pigments (calcium carbonate, kaolin clay, magnesium hydroxide, aluminum hydroxide, and sericite mica) and a swelling-type flame-retardant (a phosphor-nitrogen (P-N) organic compound) were examined. We applied the minerals either by internal addition to a pulp furnish and formation into base sheets, or by surface coating applied to commercial copy paper substrates, and finally by adding the minerals at different proportions internally to the pulp furnish and then surface coating with the P-N compound. The prepared sheets were tested for their flame-retardation performance. Service environment-simulated treatments were also conducted on the papers to observe changes in their mechanical properties, so as to find the optimal flame-retarding filler ratios and coating amount formulations. The economic efficiencies of the various formulations were also analyzed to serve as a database for research and industrial reference. In total, 5 blended formulas allowed the papers to attain a class Ⅰ flame-retardation rating. After the degradation test and economic analysis, we deemed that aluminum hydroxide and magnesium hydroxide were too expensive, and were liable to lose their fire-resistance after degradation. Sericite mica-treated paper showed lower strength losses after degradation treatment; however, the fire rating decreased to class Ⅲ. Calcium carbonate- and kaolin clay-based papers had reduced fire ratings to class Ⅱ after degradation.

Simple green synthesis of polyborosiloxanes as environmentally-safe, non-halogenated flame retardant polymers

A novel class of boron-containing siloxane copolymers (polyborosiloxanes) was synthesized by simple environmentally friendly methods. A boron containing monomer, specifically phenylboronic acid (PBA), and imide forming monomers, specifically aromatic dianhydrides 4,4′-oxydiphthalicanhydride (Oxy) and 1,1,4,4-tetracarboxylicphenyldianhydride (DAH), were employed to make terpolymers with propylamino-terminated polydimethylsiloxane (A12-PDMS). The terpolymer synthesis was carried out using various PBA : Oxy and PBA : DAH compositions ranging from 0 : 1 to 1 : 0 mole ratios. The thermal and flame retardant properties of the novel polymers were investigated. Intermediate ratios of both PBA : Oxy and PBA : DAH resulted in optimal thermal stability and flame retardancy. These novel terpolymers are promising candidates as environmentally-safe, non-halogenated alternatives to traditional flame retardant polymers.

Use of Nanoclay as an Environmentally Friendly Flame Retardant Synergist in Polyamide-6

Due to their very high levels of flame retardancy, chlorinated and brominated flame retardants had been the most widely used flame retardant additives in plastics industry. However, these flame retardants lead to formation of very toxic volatiles and by-products during fire. Therefore, the recent trend is to replace all of them with non-halogenated flame retardants. In this respect, the use of nanoclays as a synergist flame retardant is becoming more and more important. Thus, the main aim of this work was to investigate the synergistic flame retardant effect of nanoclays with phosphorous compounds in polyamide-6 composites. For this purpose, exfoliated clay nanocomposites of flame retarded/glass fiber reinforced polyamide-6 were prepared by melt compounding. A flame retardant based on phosphorus compounds was used at various levels in glass fiber reinforced polyamide-6 and nanocomposites. Flammability and fire behaviors were evaluated by limiting oxygen index, UL94 and cone calorimeter tests. Substitution of a certain fraction of the flame retardant with nanoclays was found to significantly reduce the peak heat release rate and delay the ignition in cone calorimeter. Moreover, remarkable improvements were obtained in limiting oxygen index along with maintained UL94 ratings.

A renewable waste material for the synthesis of a novel non-halogenated flame retardant polymer

The recognition of toxicity and environmental persistence of halogenated flame retardant (FR) materials has prompted the reduction in their usage across the globe. There is an immediate need for new types of non-toxic and effective FR produced preferably through sustainable routes. Here we report the synthesis and characterization of a new polyphenolic FR material based on a renewable and biodegradable starting material, cardanol (a byproduct of cashew nut processing). Cardanol was polymerized in aqueous media using various types of oxidants. The thermal properties of the resulting polymers were investigated. Polycardanol synthesized using a specific type of oxidant exhibited good thermal stability and low heat release capacity. Preliminary results obtained from this study are quite promising and indicate the possibility of synthesizing new types of FR materials from bio-based phenols.

Enhancement of the thermal stability and mechanical properties of a PMMA/aluminum trihydroxide composite synthesized via bead milling

The use of aluminum trihydroxide (ATH) fillers as non-halogen flame retardants for polymethylmethacrylates (PMMA) creates a conflict between the mechanical properties and heat resistance of the composites. Therefore, to ensure that the PMMA mechanical properties remain satisfactory, improvements in both the filler–polymer interactions and the ability to control the size and size distribution, morphology and dispersion of the fillers are required. Thus, in the present study, bead milling was used to control both the size distribution and dispersion of ATH fillers in MMA, which had an initial average size of 0.75 μm. The dispersion was obtained by alteration of the surface characteristics of ATH fillers using a silane-based dispersing agent, (3-acryloxypropyl) trimethoxysilane (APTMS). Bead milling successfully comminuted the ATH particles and prevented the formation of ATH agglomerates. The smallest average size of the ATH particles after bead milling was 300 nm. Highly dispersed ATH filler particles were observed in the TEM images of the PMMA/ATH composites. The filler–polymer interaction, i.e. the interaction parameter (B), was calculated. The effects of volume fraction, particle size distribution, and surface modification of the fillers on the results of dynamic mechanical analysis (DMA) are discussed. The thermal stability of the PMMA/ATH composites was also investigated using thermal gravimetric analysis (TGA).

Silane-functionalized Flame-retardant Aluminum Trihydroxide in Flexible Polyurethane Foam

Flexible polyurethane (PU) foams are easily ignitable and show a high burning velocity, mainly due to their high surface area-to-mass ratio and high air permeability. Consequently, flame retardants such as halogenated compounds are applied. However, the use of halogenated flame retardants is not considered beneficial in transport applications, for example, aviation or automobile, in part due to the high smoke generation. Solid nonhalogenated flame retardants, for example, aluminum trihydroxide (ATH), are known as smoke suppressants. The application of ATH in flexible (PU) foam has not yet been reported in the literature. In this study, the application of different types and amounts of ATH and the resulting structure—property relationship in the foam are investigated. The increase in the viscosity of the filled raw materials during the foaming process and the negative effects of the filler on the mechanical properties of the final foam pose particular problems in the application of ATH. To pass the FMVSS 302 test, high amounts of ATH are necessary. To overcome the mentioned drawbacks, ATH particles are functionalized by 3-aminopropyltriethoxysilane under different conditions. The synthesized products were characterized by Fourier transform infrared, energy-dispersive X-ray fluorescence analysis, and 29Si and 1H solid-state nuclear magnetic resonance spectroscopy. The silane-treated ATH particles show a significant decrease in viscosity of the ATH—polyol system of more than 20% at ATH contents of up to 60 phpp. Values of the rising behavior during foaming and the burning velocity are not affected by this silane treatment. However, the compression test of PU foams with the silane-treated ATH particles show a decrease in compression strength of up to 20% compared to untreated ATH particles in the flexible PU foam. At higher ATH contents, no effect of silanization is observed.

Thermal stability of phosphinated diethyl tartrate

Organohalogen flame retardants, particularly brominated aromatics, are popular, effective, low cost, and widely used in the plastics industry. However, an increasing concern about persistence in the environment and potential negative health effects of these materials has generated intense interest in the development of alternatives. Ideally, these should have all the positive attributes of the materials that will be replaced. In addition, it is desirable that the new materials be as “green” as possible, e.g., based on renewable resources and be degradable to nontoxic products in the environment. A series of new, non-halogenated flame retardants based on tartaric acid is being developed. Tartaric acid is a by-product of the wine industry and is readily available locally on an annual basis (Michigan is the thirteenth largest producer of wine in the U.S.). It can be readily converted to the corresponding diethyl ester. This ester may serve as the base for the development of a series of new, non-halogenated flame-retarding agents. The presence of the reactive hydroxyl groups allows the introduction of a variety of phosphorus-containing moieties. For example, treatment of diethyl tartrate with diphenylphosphinyl chloride generates diethyl 2,3-di(diphenylphosphinato)-1,4-butanedioate. This material may serve as a monomer for the preparation of various phosphorus-containing polymers and oligomers via step-growth transesterification. The thermal stability of this compound has been assessed by thermogravimetry.

Application of cyclophosphazene derivatives as flame retardants for ABS

Cyclotriphosphazene derivatives were synthesized for use as a non-halogen flame retardant for ABS. Hexachlorocyclotriphosphazene was reacted with phenol, catechol, or 2,3-dihydroxynaphthalene, respectively, and the fire retardant ability of each product in ABS resin was characterized by UL 94 and LOI tests. The mechanical properties of ABS compounds containing one of these flame retardants were also examined. The derivative (HNCP) synthesized from 2,3-dihydroxynaphthalene showed the best flame retardance among these derivatives studied. Synergistic effects with novolac were observed in the cases using the derivative (PNCP) obtained from phenol, but little synergistic effects were observed in cases using HNCP.

Flame resistance and foaming properties of NBR compounds with halogen‐free flame retardants

AbstractAcrylonitrile butadiene rubber (NBR) foams compounded with various halogen‐free flame retardants were prepared. The influence of nonhalogen flame retardants on the flame resistance and foaming properties of the NBR compounds were investigated. The foaming properties (expandability 980%–1050%, closed‐cell structure) of NBR compounds with expandable graphite (EG) and ammonium polyphosphate (APP) flame retardants were similar to the NBR base compounds which contained primarily aluminum hydroxide (ATH). The heat release capacity (HRC) ranged from 10 to 74 J/g‐K, the average heat release rate (A‐HRR) ranged from 8 to 60 kW/m2, and the total heat release (THR) ranged from 2.6 to 7.3 MJ/m2 for the nonhalogenated NBR foams with closed‐cell structure and were significantly decreased upon increasing the amounts of flame retardants. This reduction is attributed to the hard char formation and production of water from the interaction with ATH. The limiting oxygen index (LOI) and time to ignition (TTI) show opposite results. The smoke density (0.050–0.037) of the NBR foams with EG flame retardant was decreased when compared to the NBR foam (0.107). The EG flame retardant was more effective than the phosphorus/nitrogen flame retardants in reducing the HRR and smoke density. The use of both ATH and EG is very effective in improving flame resistance. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers

Flexible Polyurethane Foam with the Flame-retardant Melamine

Flexible polyurethane (PU) foams are widely used in many industrial applications, such as upholstered furniture and mattresses, automotive applications, etc. The chemical nature of the PU, the high air permeability, and the high inner surface area of the foam structure cause this material to be highly flammable. Consequently, the application of flame retardants to flexible PU foams is an important issue. The use of halogenated flame retardants is not considered optimal, in part due to the high emission level and the possible phase-out by the European Risk Assessment Body. Consequently, melamine as a nonhalogenated flame retardant is applied more and more frequently. However, little data is available regarding the application of melamine as an additive in flexible PU. This paper is concerned with the influence of melamine on the synthesis of the PU foam and the resulting material-specific properties. Especially, the increase of viscosity and the high heat capacity of melamine lead to a decrease in foaming growth and rising height with increasing melamine content. This is caused by the reduced drainage rate between the struts and the plateau borders in the foam-forming process. Here, the increase in viscosity follows the Dougherty—Krieger equation with the intrinsic viscosity of k = 3.3. The mechanical properties such as density and compression strength increase with increasing melamine content. Other properties like tensile strength and elongation decrease because of the embedding of the melamine in the PU matrix, which weakens the structure. The air permeation and number of cells also decreases because of the thickened struts caused by the reduced drainage rate in the foaming process. Furthermore, the reaction between the amino groups of melamine and the isocyanate of the PU formulation was investigated by FTIR.

Characterization of poly(ethylene- co-vinyl acetate) (EVA) filled with low grade magnesium hydroxide

Low-grade magnesium hydroxide (LG-MH) is a solid by-product that undergoes an endothermic decomposition in the temperature range of 300–750 °C. Due to its thermal behaviour and its lower cost relative to pure Mg(OH) 2, it was studied as a non-halogenated flame retardant filler in a 28% vinyl acetate (VA) content poly(ethylene- co-vinyl acetate) matrix. The solid was characterized by XRF and the crystalline phases determined by XRD, composed predominantly of Mg(OH) 2 and calcium and magnesium carbonates. Particle size reduction was performed by both mechanical as well as air jet milling in order to optimize the particle size distribution. Composites with different filler concentrations were prepared to evaluate the mechanical properties and flame retardancy by means of limiting oxygen index tests. LOI was also determined in specimens filled with commercial flame-retardants to analyse the effectiveness of this solid.

New Thinking on Flame Retardants

No one wants their bed, couch, chair, computer, or TV to catch on fire. “If an ordinary upholstered chair in your home gets ignited, it can essentially take your whole house down,” says Richard Gann, a senior research scientist at the U.S. National Institute of Standards and Technology’s (NIST) Building and Fire Research Laboratory. The most flammable part of a mattress or couch is its plastic polyurethane foam cushioning, he explains. Once a fire gets through a chair or mattress’s fabric covering and into this cushioning, it can start a catastrophic reaction that quickly leads to “flashover,” in which nearly everything combustible inside a room ignites simultaneously. Until very recently, brominated flame retardants, especially polybrominated diphenyl ethers (PBDEs), were one of the main materials used to reduce the speed with which the plastic components of consumer goods including beds, couches, chairs, and electronics could be consumed by fire. However, growing evidence shows that PBDE compounds are escaping from the products they protect and making their way into the products’ users. Moreover, the chemicals may disrupt human thyroid hormone functioning and cause other health effects, prompting many nations to ban or suspend their use in new consumer goods. [For more information on the health effects of PBDEs, see “Unwelcome Guest: PBDEs in Indoor Dust, p. A202 this issue.] Although bromine- and chlorine-containing flame retardants are still used in some products, the need for new alternatives is being driven by a confluence of policy, standards, and pressure from environmental groups. Europe banned the use of two formulations, PBDE pentaBDE and octaBDE, in 2004, the same year they were withdrawn from the North American market. A third compound, decaBDE, was banned 1 April 2008 by the European Court of Justice. Stateside, Maine has banned the use of decaBDE, the only PBDE still on the market in North America, in mattresses and residential upholstered furniture produced and sold in that state, and will extend the ban to electronics in 2010. Washington prohibits the use of decaBDE in mattresses and sets a process for a future ban in furniture and electronics if the state can identify a safer and feasible alternative that meets fire safety standards. Asian countries and other U.S. states have similar legislation in the works. “Instead of adding new fire retardant chemicals that ultimately may be shown to cause health problems, we should be asking whether we need to use these chemicals or if there are other ways to achieve equivalent fire safety,” contends Arlene Blum, a biophysical chemist and visiting scholar at the University of California, Berkeley. “So many of the chemicals we have banned in the past were flame retardants—think about asbestos, polychlorinated biphenyls, polybrominated biphenyls, tris(2,3-dibromopropyl) phosphate, PBDEs—[and] they all ended up in the environment and in people,” she points out. “We need to think carefully about adding these sorts of chemicals to consumer products before there is adequate health information.”

FORMER LUBRIZOL RESEARCHER IS CHARGED

AFTER AN INTERNAL investigation at specialty chemical maker Lubrizol, federal authorities have charged a former company employee with theft of trade secrets and conspiracy. Kyung J. Kim, a one-time senior R&D associate at Lubrizol’s Brecksville, Ohio, facility, is accused of selling confidential company information to SK Chemicals of South Korea. According to charging documents filed in U.S. District Court for the Northern District of Ohio, Kim allegedly downloaded Lubrizol trade secrets about thermoplastic polyurethanes (TPUs) and other technologies—including nonhalogen flame retardants and static control technology—and provided the information to three co-conspirators. SK Chemicals, a Lubrizol competitor, sells TPUs under the trade name Skythane. The documents allege that between 2001 and 2007, Kim met at least 17 times with SK Chemicals executives to discuss confidential technology in exchange for cash payments. At each meeting, Kim allegedly received $10,000 in $100 bills and about $1,100 in travel ex...

Cyclophosphazene을 이용한 ABS용 난연제의 합성

Non-halogen flame retardant have been focus of extensive research because of environmental problem. Hexakisphenokycyclotriphosphazene was synthesized in order to use as the flame retardant of ABS resin. And using bisphenol A, bisphenol S, and resorcinol, the polymers which contained cyclophosphazene structure were synthesized in order to also use as the flame retardants of ABS resin. All of the synthesized polymers themselves got the excellent flame retardancy. And as the molecular weight of the compound were increased, the thermal stability was increased. But when the synthesized compounds were used as the flame retardants for ABS resin, the lower molecular weight compound in these compounds showed the better flame retardancy and the better physical properties of ABS resin. In case of using resorcinol, it showed the best flame retardancy.

Synthetic hydromagnesite as flame retardant. Evaluation of the flame behaviour in a polyethylene matrix

Synthetic hydromagnesite obtained from an industrial by-product was evaluated as a non-halogenated flame retardant. It was used in combination with aluminium hydroxide (ATH) and compared with commercial flame retardants like magnesium hydroxide (MH) and natural hydromagnesite–huntite (U) in a polyolefin system of low-density polyethylene/poly(ethylene- co-vinyl acetate) (LDPE/EVA). The thermal stability and flame behaviour of the halogen free flame retarded composites were studied by thermogravimetric and differential thermal analysis (TG-DTA), limiting oxygen index (LOI), epiradiateur and cone calorimeter. It has been shown that synthetic hydromagnesite could be an alternative solution to the use of MH in non-halogenated flame retardant systems in EVA.

Techmer PM develops fire retardant for wire and cable use

To meet the growing demand for halogen-free fire retardants from wire and cable producers, Techmer PM has developed a flame-retardant additive that it says provides an optimum balance of fire security, processability and cost. Designated PM-9368E12, the new non-halogenated flame retardant will serve as Techmer PM’s flagship product in the company’s campaign to increase its market share in the wire and cable industry. The product was launched at the recent NPE 2003 show in Chicago. This is a short news story only. Visit www.addcomp.com for all the latest additives and compounding industry news.

Effects of co-disposal of wastes containing organic pollutants with municipal solid waste—a landfill simulation reactor study

Different phases of the life cycle of a landfill receiving municipal solid waste (MSW) were monitored in landfill simulation reactors (LSRs) with the aim of investigating the effects of co-disposal of wastes containing organic pollutants (OPs) with MSW. Two LSRs out of four filled with well-characterised MSW received waste materials containing OPs. These included two types of plasticised PVC flooring materials, freon-blown insulation and phosphorus- and nitrogen-based flame-protected materials. Each of the two LSRs was operated under acid fermentative and neutral methanogenic conditions, respectively as were their corresponding controls, i.e. without extra OP. The methanogenic consortia degrading MSW were hampered by the addition of wastes containing OPs, probably due to the presence of Freon R11 and its degradation product, R21. The concentrations of R11 and R21 ranged between 0.1 and 1800 mg m −3 depending on the biogas production rate in the OP-amended LSRs. Losses of butylbenzyl- (26%) and bis(2-ethylhexyl)phthalate (15%) from one of two flooring materials was observed, whereas the other remained unaffected. Methanogenic conditions favoured the loss of plasticisers as compared to acidogenic conditions. Total phosphorus was significantly higher in the OP-spiked LSRs, which indicated a transformation of the non-halogenated flame-retardants.