Additive-type Flame Retardants Research Articles

Advancements in Flame-Retardant Systems for Rigid Polyurethane Foam.

The amplified employment of rigid polyurethane foam (RPUF) has accentuated the importance of its flame-retardant properties in stimulating demand. Thus, a compelling research report is essential to scrutinize the recent progression in the field of the flame retardancy and smoke toxicity reduction of RPUF. This comprehensive analysis delves into the conventional and innovative trends in flame-retardant (FR) systems, comprising reactive-type FRs, additive-type FRs, inorganic nanoparticles, and protective coatings for flame resistance, and summarizes their impacts on the thermal stability, mechanical properties, and smoke toxicity suppression of the resultant foams. Nevertheless, there are still several challenges that require attention, such as the migration of additives, the insufficient interfacial compatibility between flame-retardant polyols or flame retardants and the RPUF matrix, and the complexity of achieving both flame retardancy and mechanical properties simultaneously. Moreover, future research should focus on utilizing functionalized precursors and developing biodegradable RPUF to promote sustainability and to expand the applications of polyurethane foam.

Synthesis and characterization of a novel P/N containing flame retardant and its effect on flame-retardancy, thermal and mechanical properties of epoxy/clay nanocomposites

A P/N containing flame retardant DOPO-QN was synthesized by a reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 8-hydroxyquinoline (QN). Its chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) like 1H, 13C, 31P NMR, and high-resolution mass spectrometry (HRMS) techniques. The synthesized DOPO-QN was employed as an additive type flame retardant in combination with clay nanomer 1.34TCN (NC) in diglycidyl ether of bisphenol A/4,4ʹ-diaminodiphenlsulfone (DGEBA/DDS) to synthesize epoxy thermosets. The fire behavior of synthesized epoxy thermosets was studied by UL-94, limiting oxygen index (LOI), and cone calorimeter tests. The EP/DOPO-QN (1.5%P)/NC sample passed the UL-94 test with a V-0 rating and LOI value of 26.5%. A decrease in peak heat released, carbon monoxide, and carbon dioxide emissions was observed in the cone calorimeter test. Thermogravimetric analysis (TGA) of epoxy thermosets showed an increase in thermal stability at a higher temperature range on the formation of nanocomposites. Also, a remarkable improvement in storage modulus was observed for the EP/DOPO-QN (1.5%P)/NC sample containing 2.0% NC in dynamic mechanical analysis (DMA).

Fabrication of flexible polyurethane/phosphorus interpenetrating polymer network (IPN) foam for enhanced thermal stability, flame retardancy and mechanical properties

Even though organophosphorus additives can improve flame retardancy and compress strength of flexible polyurethane foam (FPUF), but thermal stability and resilience are deteriorated. In this work, phosphorus-containing monoacrylate and triacrylate, (dimethoxyphosphoryl)methyl acrylate (DMPMA) and tris(acryloyloxymethyl)phosphine oxide (TAMPO), were synthesized. The liquid DMPMA and/or TAMPO were added into FPUF ingredients with radical initiator and polymerized in the heating process after foaming to form FPUF/polyacrylate composites. The neat and modified foams were controlled to have similar densities. Gel content of more than 96% was obtained for FPUF incorporated with TAMPO. And structure of interpenetrating polymer network (IPN) of FPUF3-5 loaded 20 wt% DMPMA and TAMPO of polyol (ratio of 3:1, 1:1 and 1:3 respectively) was further confirmed by their bicontinuous phase morphology with nanoscale domain uniformly distributed. All modified foams attain improved flame retardancy. Simultaneously increased thermal stability, compression force deflection (CFD) value and resilience were achieved by FPUF4-5. Especially, FPUF4 exhibits satisfied flame retardancy (limited oxygen index of 22.1%, pass of TB117-2000 vertical burning test, prolonged time to ignition, 49% decrement of peak heat release rate and 33% reduction of total heat release), elevated thermal stability and improved compressive (15% improvement of CFD) and resilient (5.2% raise of resilience) properties, concurrently. Therefore, DMPMA and TAMPO have great potential as liquid additive-type flame retardants for manufacturing flame retardant, supportive and comfort FPUF in seating and cushioning applications.

Synthesis and characterization of flame-retardant rigid polyurethane foams derived from gutter oil biodiesel

In this study, gutter oil biodiesel-based polyols (GOBP) and a reactive-type flame retardant named diethyl bis(2-hydroxyethyl)-aminomethylphosphonate (BHAPE) were both synthesized. Subsequently, gutter oil biodiesel-based flame-retardant rigid polyurethane foams (BPUFs) were prepared with GOBP, BHAPE, aluminum hydroxide (an additive-type flame retardant) and polymeric diphenylmethane diisocyanate. The properties of the BPUFs, including density, thermal conductivity, compressive properties, chemical component, morphology, thermal stability, limiting oxygen index, cone calorimetry testing, char residues stability were characterized. Among them, BPUF-AB owning 6.97 wt% of GOBP, 18.59 wt% of BHAPE and 39.77 wt% of aluminum hydroxide obtained a lower density of 0.097 g/cm3, a lower thermal conduction of 0.048 W/(m * k) and the highest compressive strength of 187 ± 13 kPa. Fire testing revealed a highest limiting oxygen index value of 30.1% and passed the UL-94 standard test. Cone calorimetry testing revealed that the peak heat release rate and peak smoke production release of BPUF-AB were reduced by 51.08% and 57.10%, respectively. Meanwhile, the total heat release rate and total smoke production were respectively decreased by 36.88% and 40.79%. The results indicate that BPUFs derived from gutter oil biodiesel are prosperously potential biomaterials with good thermal stability for fire insulation porous materials in future architecture applications.

A phosphorous-based bi-functional flame retardant for rigid polyurethane foam

A bi-functional flame retardant for rigid polyurethane foam (RPUF), denoted as PDEP, was designed and synthesized. PDEP contained two phosphorus-based moieties: phosphophenanthrene (DOPO) and a phosphate (DEP), which may exert different functions at different temperatures. DEP and DOPO moieties in sequence decomposed with increasing temperature, continuously releasing and holding high-content phosphorus-oxygen free radicals with quenching effect and producing viscous residues to bond and integrate other char species leading to high barrier effect. The flame retardant modes of action of PDEP was confirmed by experiments using thermogravimetric analysis-Fourier transform infrared (TGA-FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), FTIR and SEM. PDEP was incorporated into RPUF system via co-cured with other polyol components. Using expandable graphite (EG) as additive-type flame retardant, an enhanced flame retardancy in RPUF was observed.

Multi-Functional Carbon Fiber Reinforced Composites for Fire Retardant Applications

Development of multifunctional flame retardant (FR) polymer composite was done. Flame retardant polymer composite was prepared by modifying diglycidylether of bisphenol-A (DGEBA) epoxy. Modification involved two types of FR. Reactive type FR used was phosphoric acid and additive type FR used was magnesium hydroxide. Composite was fabricated using resin infusion under flexible tooling (RIFT) process. Different FR epoxy samples were evaluated by compression test, UL 94. The carbon fiber reinforced polymer composite with attributes of flame retardancy were characterized using in-plane shear test, to estimate the structural properties, and UL-94 test, to estimate the fire performance. FR composite exhibited UL-94 rating of V-1 and a shear modulus of 9.7 GPa, which proved it to multifunctional.

Influence of Flame Retardants on LLDPE‐Date Pit Fiber Composites: Thermal Degradation and Tensile Properties

AbstractLinear low density polyethylene (LLDPE)‐date pit composites incorporated with different flame retardants were synthesized by extrusion and casted into shape by injection moulding. Several additive type flame retardants viz. Ammonium polyphosphate (APP), Melamine phosphate (MP), Ammonium dihydrogen orthophosphate (ADOP), Diammonium hydrogen phosphate (DAHP) were added to enhance the flame retarding behaviour of composites. The thermal analysis and mechanical properties of composites have also been investigated. Thermogravimetric analysis (TGA) revealed a two step degradation mechanism of all the blends. The kinetic parameters such as activation energy and differential conversion function f(ɑ) were evaluated using three different non isothermal methods based on the iso conversional plots: Friedman (FM), Ozawa‐Flynn‐Wall (OFW) and Coats‐Redfern (Modified). The average value of activation energy of thermal degradation of blends evaluated using Friedman method; was used to depict the actual mechanism of degradation by fabricating the Criado's master plot. Addition of any kind of flame retardant led to an improvement in both tensile as well as flexural strength of composites. According to the results of Limiting Oxygen Index (LOI) and UL‐94 testing, addition of APP led to the significant improvement in the flame retardancy of LLDPE composites.

An anti-melt dripping, high char yield and flame-retardant polyether rigid polyurethane foam

Endowing rigid polyurethane foam (PUF) with a good fire-retardancy is essential for improving fire safety. Chemical improvement in fire-retardancy by using reactive-type flame retardants is better because of the disadvantages of traditional additive-type flame retardants. A reactive flame retardant tri-glycidyl phosphate (POG), which was synthesized by using phosphorus oxychloride and glycidol, was bound to the cross-linked network structure of PUF. The effects of POG on the physical-mechanical properties, morphology, thermal stability and fire-retardancy of PUF system were systematically investigated. Research results showed that POG resulted in an improvement in the thermal insulation ability and a slight decrease in the compressive strength of PUF. Furthermore, thermogravimetric analysis certified that the thermal stability and the char yield at 700 °C of PUF were significantly enhanced by incorporating POG. The limiting oxygen index increased to 22.3% with rising loading of POG. Moreover, a 30.2% decline in total heat release was achieved, the time to flameout was significantly shortened. Additionally, the vertical burning test illustrated that POG effectively limited the spread of flame and eliminated melt dripping. Further study confirmed that the fire-retardancy of PUF was significantly improved by inhibiting flame in the gas phase and charring in condensed phase.

New Flame Retardant and Antimicrobial Paints Based on Epoxy Paint Incorporated by Hexachlorocylodiphosphazane Derivatives for Protective Coating

Flame retardants can be incorporated into polymeric material either as additives or as reactive materials. Additive type flame retardants are widely used by means of blending them with a specific polymeric material. In this particular research, hexachlorocylodiphosphazane derivatives type (I-II) were synthesized for use as flame retardant and antimicrobial additives with epoxy varnish. These additives are physically incorporated into the epoxy varnish formula. Experimental coatings were manufactured on a laboratory scale and applied by brush on wood and steel panels. The fire retardant ability of each coating type was characterized using the limiting oxygen index (LOI) test. The mechanical properties of these flame retardants were also examined to evaluate the drawbacks of the additives. Results of the LOI indicated that coating with these compounds containing chlorine, nitrogen and phosphorus exhibit a very good retardant effect, when blended with epoxy varnish comparing with the blanket sample which not contain on the hexachlorocylodiphosphazane derivative as a additives. The hexachlorocylodiphosphazane derivative also exhibit mild results as preservative against microbiological attack. The mechanical properties of the painted dry films were investigated acordinting to ASTM.

Engineering carbon nanotubes wrapped ammonium polyphosphate for enhancing mechanical and flame retardant properties of poly(butylene succinate)

The performance of CNTs with different amounts and dispersion states were explored in the flame retardant system as PBS/APP. Herein, A series of CNTs wrapped ammonium polyphosphate (named CAPP) were successfully prepared and characterized, and then blended into Poly(butylene succinate) (PBS) as an additive-type flame retardant. The obtained PBS/CAPP contributes to forming much more graphitized char layers to reduce the heat transfer and toxic gases release. For instance, PBS-3 containing 20% CAPP1 wrapped by only 1% of CNTs shows the best anti-dripping effect and the lowest toxic gases release, where CO2 and CO yield dramatically reduced by about 68.3% and 72.6%. With the same content of CNTs, the tensile strength, elongation at break and unnotched impact strength of PBS-3 increased about 10.8%, 14.2% and 5.3% than PBS-5 (CNTs added directly). Thus, the well dispersion state of moderate CNTs has a positive impact on improving mechanical properties, flame retardancy and smoke suppression.

Epoxy resin flame-retarded via a novel melamine-organophosphinic acid salt: Thermal stability, flame retardance and pyrolysis behavior

A melamine-organophosphinic acid salt (MDOP) was synthesized via neutralization of dibenzo[c,e][1,2]oxaphosphinic acid (DOPA) with melamine, and used as an additive-type flame retardant for epoxy resin (EP). Thermal stability and flame retardance was comprehensively evaluated via thermogravimetric analysis (TGA), UL-94 vertical burning test, limiting oxygen index (LOI) and cone calorimetry. The cured epoxy easily passed UL-94 V-0 rating with 0.33% content of P (5 phr MDOP); and LOI value of 38.0% was further achieved with 10 phr MDOP. The peak heat release (PHRR), total heat release (THR), total smoke production (TSP) and fire growth rate (FIGRA) were all reduced with the incorporation of MDOP. The pyrolysis behavior of the flame-retardant EP systems from Py-GC/MS and TG-FTIR suggested that MDOP played the role of flame retardance in both condensed and gaseous phases. Interestingly, the incorporation of MDOP did not deteriorate the mechanical properties of epoxy resin.

An efficient phosphonate-based ionic liquid on flame retardancy and mechanical property of epoxy resin

In order to develop a highly efficient flame-retardant system, a phosphonate-based ionic liquid named 1-vinyl-3-(diethoxyphosphoryl)-propylimidazolium bromide (IL) was synthesized and introduced into epoxy resin (EP). With only 4 wt% loading, EP/IL composite passed UL-94 V-0 rating, and its limiting oxygen index value increased to 34.9% from 25.9% for neat epoxy resin. The char yield of EP/IL-2 (2 wt%) was improved by 58.3%, and its peak of heat release rate was reduced by 65% compared with that of neat EP. The reason is that the presence of IL promoted the forming of a compact and stable phosphorus-rich residual chars. Unlike traditional additive-type flame retardant, it is very interesting that the introduction of IL changed the color and transparency of EP few and enhanced mechanical property of neat EP remarkably. Owing to the excellent compatibility and steric effect between IL and EP matrix, tensile strength was increased to 108.6 MPa for EP/IL sample from 84.9 MPa for neat EP, indicating the outstanding reinforcement effect of IL on EP composites.

A facile method to flame-retard epoxy resin with maintained mechanical properties through a novel P/N/S-containing flame retardant of tautomerization

A novel phenylphosphonic di-benzothiazolyl amide (PPDAB) and its imine-type tautomer were successfully synthesized via the amidation of phenylphosphonic dichloride (PPDC) with 2-aminobenzothiazole (ABZ), and used to flame-retard epoxy resin (EP). In the help of PPDAB-Amine as an additive-type flame retardant and PPDAB-Imine as a reactive-type flame retardant, PPDAB showed excellent general properties in epoxy resin. EP with 0.69wt% of phosphorus achieved UL-94 V-0 rating, and the LOI value of it was increased to 31.0%. Compared with the EP, its performances in terms of the peak of heat release rate (PHRR), total heat release (THR), and smoke production rate (SPR) obtained from cone calorimeter were obviously improved. Besides, EP-PPDAB in which the amount of PPDAB was lower than 10wt% also exhibited similar glass transition temperature (Tg) to EP, and well-maintained mechanical properties in terms of tensile strength and impact strength.

In situ preparation of reduced graphene oxide/DOPO-based phosphonamidate hybrids towards high-performance epoxy nanocomposites

Abstract The work reports a strategy based on piperazine-reduced graphene oxide (rGO)/piperazine-based DOPO-phosphonamidate (PiP-DOPO) to overcome the challenge of the dispersion of graphene and mechanical deterioration of epoxy resin (EP) matrix with additive-type flame retardants. Graphene oxide (GO) was functionalized and reduced by piperazine simultaneously, and then incorporated into PiP-DOPO through in situ reaction, resulting in the formation of the hybrids (PD-rGO). Subsequently, the PD-rGO was incorporated into epoxy resin (EP) to fabricate nanocomposite. The structure and thermal properties of PD-rGO were well characterized. The presence of PD-rGO in EP improved the char yields at 700 °C and reduced the maximum mass loss rate under nitrogen, indicating the improved thermal stability at elevated temperature. The evaluation of combustion behavior demonstrated that the PHRR and THR values were decreased significantly by 43.0% and 30.2% by the addition of 4 wt% PD-rGO10 (10 wt% rGO in hybrid) in EP respectively, in comparison to neat EP. The epoxy composite with 4 wt% PD-rGO5 (5 wt% rGO in hybrid) could pass UL-94 V0 rating and the LOI was 28.0%. The flame retardant mechanism could be attributed to the synergism between two compositions in PD-rGO hybrid: the PiP-DOPO was favorable to flame spread inhibition in UL-94 burning test, while the barrier effect of graphene was dominant in terms of heat release rate suppression. Moreover, the addition of PD-rGO hybrid led to slightly improved storage modulus and tensile strength, due to the high stiffness of graphene in hybrids. The PD-rGO hybrid combines the outstanding mechanical behavior of graphene with the good flame retardant effect of DOPO-based compounds, which provides a promising solution to high performance epoxy nanocomposites with improved flame retardant and mechanical properties simultaneously.

Flame Retardancy of Carbon Fibre Reinforced Sorbitol Based Bioepoxy Composites with Phosphorus-Containing Additives.

Carbon fibre reinforced flame-retarded bioepoxy composites were prepared from commercially available sorbitol polyglycidyl ether (SPE) cured with cycloaliphatic amine hardener. Samples containing 1, 2, and 3% phosphorus (P) were prepared using additive type flame retardants (FRs) resorcinol bis(diphenyl phosphate) (RDP), ammonium polyphosphate (APP), and their combinations. The fire performance of the composites was investigated by limiting oxygen index (LOI), UL-94 tests, and mass loss calorimetry. The effect of FRs on the glass transition temperature, and storage modulus was evaluated by dynamic mechanical analysis (DMA), while the mechanical performance was investigated by tensile, bending, and interlaminar shear measurements, as well as by Charpy impact test. In formulations containing both FRs, the presence of RDP, acting mainly in gas phase, ensured balanced gas and solid-phase mechanism leading to best overall fire performance. APP advantageously compensated the plasticizing (storage modulus and glass transition temperature decreasing) effect of RDP in combined formulations; furthermore, it led to increased tensile strength and Charpy impact energy.

Highly Effective P–P Synergy of a Novel DOPO-Based Flame Retardant for Epoxy Resin

A novel flame retardant (FR) DOPO-PEPA, which was synthesized via Atherton–Todd reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 1-oxo-4-hydroxymethyl-2,6,7-trioxa-l-phosphabicyclo[2.2.2]octane (PEPA), was used as an additive-type FR in epoxy resin (EP). The results of the limiting oxygen index (LOI), vertical burning test, and cone calorimeter test indicated that the flame retardance of FR-EP composites is dependent on the chemical structure of phosphorus-based FRs. EP/DOPO-PEPA shows pretty good mechanical properties and a relatively high degree of cross-linking. Furthermore, the synergy as DOPO-PEPA was more efficient than that of DOPO or PEPA alone to flame retardant EP. When the FR additives were 9.1%, the EP/DOPO-PEPA acquired a LOI value of 35%, UL94 V-0 rating, and the lowest peak of heat release rate (PHRR) of 595 kW/m2. Furthermore, its continuous and firm char residue layer also reinforced this kind of action.

A Novel Organophosphorus Hybrid with Excellent Thermal Stability: Core-Shell Structure, Hybridization Mechanism, and Application in Flame Retarding Semi-Aromatic Polyamide.

An organophosphorous hybrid (BM@Al-PPi) with unique core-shell structure was prepared through hybridization reaction between boehmite (BM) as the inorganic substrate and phenylphosphinic acid (PPiA) as the organic modifier. Fourier transform infrared spectra (FTIR), solid state (31)P and (27)Al magic angle spinning nuclear magnetic resonance, X-ray diffraction, and element analysis were used to investigate the chemical structure of the hybrids, where the microrod-like core was confirmed as Al-PPi aggregates generated from the reaction between BM and PPiA, and those irregular nanoparticles in the shell belonged to residual BM. Compared with the traditional dissolution-precipitation process, a novel analogous suspension reaction mode was proposed to explain the hybridization process and the resulting product. Scanning electronic microscopy further proved the core-shell structure of the hybrids. BM exhibited much higher initial decomposition temperature than that of Al-PPi; therefore, the hybrid showed better thermal stability than Al-PPi, and it met the processing temperature of semi-aromatic polyamide (HTN, for instance) as an additive-type flame retardant. Limiting oxygen index and cone calorimetric analysis suggested the excellent flame-retardant performance and smoke suppressing activity by adding the resulting hybrid into HTN.

Synthesis and characterisation of the flame retardant properties and corrosion resistance of Schiff’s base compounds incorporated into organic coating

Purpose – This paper aims to report on the synthesis and characterisation of new flame retardants and anticorrosive additives based on Schiff’s base compounds, which were added physically to organic coating. Design/methodology/approach – Flame retardants are incorporated into polymeric materials either as additives or as reactive materials. Additive-type flame retardants are widely used by incorporating into polymeric materials by physical means. In this research, Schiff’s base (azomethine) compounds are added physically to alkyd paint as flame-retardant additives. Elemental analysis, infrared spectroscopy and proton nuclear magnetic resonance spectroscopy were used to characterise the structure of the prepared Schiff’s base compounds. Thermal gravimetric analysis was used to evaluate their thermal stability. Experimental coatings were manufactured on a laboratory scale, and then applied by brush on wood and steel panels. Findings – Results of an oxygen index value indicated that alkyd paints containing Schiff’s base compounds as additives exhibit very good flame-retardant effects. Also the physical, mechanical and corrosion resistance properties were studied to evaluate the drawbacks of the additives. The additives did not affect the flexibility of the paint formula. The gloss and the impact strength were decreased by the additives, but the hardness, adhesion and corrosion resistance were significantly improved by these additives. Research limitations/implications – Alkyd resins are the most extensively used synthetic polymers in the coating industry. Nitrogen compounds are a small but rapidly growing group of flame retardants which are in the focus of public interest concerning environment-friendly flame retardants. So, the focus of this study is on Schiff’s base compounds as flame retardants and anticorrosive additives for alkyd resins to assess their applicability. Practical implications – Schiff’s base compounds can be used as new additives in paint formulations to improve the flame-retardant and corrosion properties. Originality/value – In recent years, there has been considerable interest in the nitrogen-based family of materials because they not only have a wide range of thermal and chemical stabilities, but can also provide improved thermal and flame-retardant properties to polymers. The present paper reports on the synthesis and characterisation of Schiff’s base compounds and their performance in alkyd resin coatings.

Preparation and Application of Water-Based Fire Retardant of Ammonium Phosphate

The water-based fire retardant is one kind of additive type flame retardant, which uses water as the dispersion medium and improves the flame retardant performance of wood, fabric or cardboard by spraying or dipping. In this paper, ammonium dihydrogen phosphate and diammonium phosphate were used as raw materials for preparing the water-based flame retardants according to four different proportions of 80:20, 70:30, 60:40 and 50:50. Three kinds of fabrics were disposed with the retardant firstly, and then dried in the air, at last immersed in water, liquid soap and detergent solution with one hour. Air dried fabrics were characterized by differential thermal and thermal gravimetric analysis, and effect of water-based fire retardant of ammonium phosphate on the thermal decomposition properties also discussed on the basis of the experimental data. These results may have significant potential towards exploring preparation and application of other water-based flame retardants.

Synthesis and performance of flame retardant additives based on cyclodiphosph(V)azane of sulfaguanidine,1,3-di-[N/-2-pyrimidinylsulfanilamide]-2, 2, 2.4, 4, 4-hexachlorocyclodiphosph(V)azane and 1,3-di-[N/-2-pyrimidinylsulfanilamide]-2, 4-di[aminoacetic acid]-2, 4-dichlorocyclodiphosph(V)azane incorporated into polyurethane varnish

Cyclophosphazenes and their polymeric products are some of the oldest and best known class of nitrogen and phosphor containing compounds. In recent years there has been considerable interest in the phosphazene-based family of materials due to the wide range of thermal and chemical stabilities associated with them. In addition, these materials are capable of imparting flame-retardant properties when incorporated into polymers and their composites. Flame retardants can be incorporated into polymeric materials either as additives or as reactive materials. Additive type flame retardants are widely used by means of blending them with a specific polymeric material. In this particular research, cyclodiphosph(V)azane of sulfaguanidine,1, 3-di-[N/-2-pyrimidinylsulfanilamide]-2, 2, 2.4, 4, 4-hexachlorocyclodiphosph(V)azane and 1, 3-di-[N/-2-pyrimidinylsulfanilamide]-2, 4-di[aminoacetic acid]-2, 4-dichlorocyclodiphosph(V)azane were synthesized for use as flame retardant additives with polyurethane varnish. These additives are physically incorporated into the polyurethane varnish formula. Experimental coatings were manufactured on a laboratory scale and applied by brush on wood and steel panels. The fire retardant ability of each coating type was characterized using the limiting oxygen index (LOI) test. The mechanical properties of these flame retardants were also examined to evaluate the drawbacks of the additives. Results of the LOI indicated that coating with these compounds containing chlorine, nitrogen and phosphorus exhibit a very good retardant effect, when blended with polyurethane varnish. Cyclodiphosph(V)azane of 1,3-di-[N/-2-pyrimidinylsulfanilamide]-2, 2, 2.4, 4, 4-hexachlorocyclodiphosph(V)azane showed the best flame retardant and mechanical properties of the additives investigated.