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The danger of vapour lock, generation of vapor bubbles inside the aircraft fuel system, needs a well-documented understanding to establish safe operating confines at existing fuel temperature and pressures. The aim of the research is specifically to make contributions in the direction of the present scientific studies of UL aviation gasoline initiatives in piston aircrafts, globally specifically aiming on the vapor locking tendencies of aviation fuels, motor fuels and the blends and comparing the results both experimentally and statistically. Chemical and physical properties of the fuels were tested and categorised based on hydrocarbon types and properties. Study considered nine variables for vapor lock. Twenty-three aviation fuels from various literatures were collected, model equations derived, and respective comprehensive factor scores were calculated. The model was applied to the 14 fuels in this study and their respective comprehensive factor scores were calculated and ranked from the best to worst. The temperature of the gasoline as it approaches the carburettor was experimentally derived for comparative analysis with the comprehensive factor scores. Results showed that Kaiser’s Measure of Sampling Adequacy (MSA) measure of sampling adequacy value is 0.728. Four common factors and their cumulative variance proportion of rotation sums of squared loadings has reached 95.530%. Based on the loadings of the rotated components, PC1 has strong significant correlation with VL index of value 0.917. Among the aviation rated fuels, for vapor lock tendency UL 82, UL 87, SWIFT UL 102, SWIFT Binary Blend and 100 SF have the highest factor score. Fuels AVGAS 100LL (D910), AVF1, AVF2, AVF4, AVGAS, Leaded 91/98, and UL 94 exhibited very poor vapor lock tendencies. RON 98 exhibited the best VL protection among all the tested fuels in this study with ccomprehensive factor scores of 0.126166 and the best experimental temperature of the gasoline as it approaches the carburettor was also exhibited by RON 98. The findings showed that RON 98 able to outperform the commercial AVGAS in terms of vapor locking characteristics.

The article presents the results of research on electrically conductive hard-to-burn composite materials based on polyethylene, graphite, and some flame retardants. It is shown that optimal electrical conducting properties and the flammability rating (V0) in accordance with UL 94 test are achieved by modifying the graphite-containing composite material based on low-pressure polyethylene with ammonium polyphosphate and (or) aluminum hydroxide. It is shown that the percolation threshold of a composite material based on high-pressure polyethylene and graphite is observed at significantly higher values of the mass fraction of graphite. It is concluded that the reduction of the percolation threshold of polyethylene when filled with graphite is facilitated by an increase in the degree of crystallinity of the binder, and the formation of structured continuous conducting clusters in the composite material is observed at lower values of the mass fraction of the filler. As a result, the thermal conductivity and heat resistance of the composite material are increased owing to more efficient delocalization of the supplied heat. A number of electrically conductive hard-to-burn materials were obtained and characterized. These data allow us to directly adjust the values of the specific volume electrical resistance, physical and mechanical properties, heat resistance, and, to a certain extent, flame resistance.

The aim of this study is to investigate the effect of fiber length and loading on physico-mechanical and flammability properties of Cyrtostachys renda (CR) fiber-reinforced phenolic composites. Waste based Cyrtostachys renda (CR) fiber reinforced phenolic resin derived from cashew nut shell liquid (CNSL), bio-composite has been studied. Composites with alkali treated CR fiber length in the ranges of 1.18–0.6, 0.6–0.3 and less than 0.3 mm in 20 wt% and 40 wt% based on weight of phenolic resin were prepared by hot compression. Flammability, water absorption, tensile/flexural/impact tests were carried out on the composites and also characterized by scanning electron microscope (SEM). Composite containing 40 wt% fiber of length less than 0.3 mm has the highest tensile and flexural strengths of 34.27 MPa and 65 MPa respectively. It has been found that water absorption and thickness swelling increases as weight % of fiber increases. For the Underwriters Laboratories (UL 94), all the neat phenolic and addition with CR fiber exhibited NC and H-B classifications for vertical and horizontal respectively, however Limiting Oxygen Index (LOI), of neat phenolic dropped from 29.33 to 26 and 25 for 20 wt% and 40 wt% respectively. Morphology of the tensile fractured laminates revealed that micro pores in fibers are filled with phenolic resin, hence increases the interfacial bonding between fiber and the matrix. The research findings provision that CR fiber reinforced phenolic composites is potential to be utilized as green and biodegradable composites for interior components of automotive and aviation industry.

Polycarbonate (PC) is widely used as a matrix in light diffusing material due to its high transparency. To prepare a light diffusing material, PC is blended with microparticles to scatter the incoming light and create haze without suffering much detriment in light transmittance. It also becomes critical to endow light diffusing PC with concurrent flame retardancy to extend its advanced application. A highly efficient and multifunctional potassium sulfonate functionalized organosilica microspheres (OM-SO3K) were synthesized and employed to produce light diffusing and flame-retardant PC. When the addition of OM-SO3K was only 0.4 mass%, the transmittance and haze of the composite were 78.6% and 90.2%, respectively, while the limiting oxygen index was increased significantly to 37.5% and the V-0 rating of UL 94 test was attained. The flame-retardant mechanism was studied by the characterization of pyrolysis gas, TGA, cone calorimeter test and the analysis of charred residue.

This study aimed to develop an organic/inorganic synergistic flame retardant on polyethylene (PE). Hexakis-(4-boronic acid-phenoxy)-cyclophosphazene (CP-6B) was used as organic flame retardant to improve the flame retardant efficiency of aluminum hydroxide (ATH) on PE. The limiting oxygen index (LOI) value of PE/20 %ATH/20 %CP-6B reached 27.0 %, and vertical burning (UL 94) V-0 rating was attained. The peak heat release rate (pk-HRR) of PE/20 %ATH/20 %CP-6B was 33.7 % and 75.5 % of pure PE and PE/40 %ATH, respectively. The flame retardant mechanism of PE composites was also investigated using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), muffle furnace, Fourier transform infrared (FTIR), and Pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS). The results showed that ATH/CP-6B was an efficient flame retardant, which was effective in the gas phase and condensed phase simultaneously. CP-6B improved the flame retardant efficiency of PE/ATH and reduced the effect of ATH on the mechanical properties of PE.

The synergist of phosphorus and silicon-containing benzoxazine (p-BOZ) was prepared through three steps using phenylphosphonic dichloride, 3-aminopropyltriethoxysilane, and 4-methoxyphenol as raw materials. The structure of p-BOZ was demonstrated by 1H NMR. Ammonium polyphosphate (APP) and melamine (ME) were compounded to form an intumescent flame-retardant (IFR) system that can remarkably improve the flame retardancy of polyoxymethylene (POM). The performances of APP/ME/p-BOZ and the related mechanisms were studied by employing limited oxygen index (LOI), UL 94 rating, cone calorimeter test (CONE), thermogravimetric analysis (TGA), Raman spectral analysis, and scanning electron microscope (SEM). The results showed that the introduced p-BOZ can effectively enhance the char formation ability of the APP/ME/p-BOZ system in the condensed phase and improve the gas-phase performance simultaneously. The POM composites containing 2 wt% p-BOZ compounding with 20 wt% APP and 6 wt% ME reached UL94 V-0 rating and a LOI value of 42.8%. Meanwhile, average HRR, MLR, EHC, SEA, and TSP of the composite all exhibited significant reduction, further conforming that p-BOZ can act as an effective flame-retardant synergist and a smoke suppressant. The synergist of phosphorus and silicon-containing benzoxazine (p-BOZ) was prepared. The POM composites containing 2 wt% p-BOZ compounding with 20 wt% APP and 6 wt% ME reached UL94 V-0 rating and a LOI value of 42.8%.

Purpose The flammability of poly-acrylate (PA) resin is a major disadvantage in applications that require flame resistance. Many studies, including the authors’ previous study, have proved that covalent-incorporated phosphorous-containing (P-containing) monomer onto the PA resin can exhibit better flame resistance than that by an additive approach. However, other properties such as thermal stability, coating properties are still deteriorated. To further improve the flame-retardancy and other comprehensive properties of the P-containing PA resin, in this study, melamine formaldehyde(MF) resin was used not only as a curing agent to enhance the coating properties of the PA resin, but also as a nitrogen-containing (N-containing) resin to form a P-N synergistic effect and therefore further improve its flame retardancy. Design/methodology/approach Epoxy resin phosphorous acid-modified (EPPA-modified) PA (EPPA-PA) resin was first prepared and then using MF resin as curing agent. The flame retardancy of the cured resin was tested by the limiting oxygen index (LOI) and UL 94 methods. The thermal stability of the cured resin was studied by TGA. The coating technology such as adhesion property, pencil hardness and anti-solvent properties were characterized according to methods of International Standards ISO2409-1992, ISO 15184-1998 and ISO-15184-2012, respectively. The micro-char morphology of the char residue was observed by SEM. Findings The results showed that by using MF resin as curing agent has provided the PA resin with excellent coating properties and thermal stability, but also gave a P-N synergistic effect which has greatly enhanced the flame retardancy of the cured resin. The cured resin system containing only 1.7 Wt.% P content and 5.3 Wt.% N content can reach a LOI of 26.9 per cent and pass the V-0 rating in the UL-94 test. Research limitations/implications This resin system releases formaldehyde due to the MF resin. Practical implications It is expected that the large-scale production of this EPPA-PA resin cured by MF resin system will enable practical industrial applications. Originality/value This method for the synthesis of a P- and N-containing PA resin system is newfangled.

A halogen-free, organic boron/nitrogen compound, 2,4,6-tris-(4-boronphenoxy)-(1,3,5)-triazine (TNB), was synthesized. The thermal and flame-retardant properties of epoxy resins (EP) containing TNB were investigated based on TGA, limiting oxygen index (LOI), vertical burning (UL 94) and cone calorimeter tests. The results showed that the residual char of EP increased after TNB was present. The LOI value of EP/20%TNB reached 31.2% and UL 94 V-0 rating was achieved. The peak heat release rate and total heat release of EP/20%TNB reduced to 305.3 kW/m2 and 58.0 MJ/m2, respectively. In addition, the flame-retarding mechanism was investigated using X-ray diffraction, scanning electron microscopy, laser Raman spectroscopy, elemental analysis, and thermogravimetric analysis-infrared spectroscopy. The results show that TNB is an efficient flame retardant, which is effective in the gas and condensed phases simultaneously. Keywords: Triazine derivative, Boron/nitrogen flame retardant, Epoxy resin, Flame-retarding mechanism

This research aims to determine the mechanical properties of sugar palm fiber (Arenga pinnata Wurmb. Merr) (SPF)/glass fiber (GF)-reinforced poly(lactic acid) (PLA) hybrid composites for potential use in motorcycle components. The mechanical (hardness, compressive, impact, and creep) and flammability properties of SPF/GF/PLA hybrid composites were investigated and compared to commercially available motorcycle Acrylonitrile Butadiene Styrene (ABS) plastic components. The composites were initially prepared using a Brabender Plastograph, followed by a compression molding method. This study also illustrated the tensile and flexural stress–strain curves. The results revealed that alkaline-treated SPF/GF/PLA had the highest hardness and impact strength values of 88.6 HRS and 3.10 kJ/m2, respectively. According to the results, both alkaline and benzoyl chloride treatments may improve the mechanical properties of SPF/GF/PLA hybrid composites, and a short-term creep test revealed that the alkaline treated SPF/GF/PLA composite displayed the least creep deformation. The findings of the horizontal UL 94 testing indicated that the alkaline-treated SPF/GF/PLA hybrid composites had good flame resistance. However, alkaline-treated SPF/GF/PLA composites are more suitable materials for motorcycle components.

Simultaneous flame retardancy and tensile strength enhancement of poly(lactic acid) (PLA) is particularly important due to its eco-friendliness and potential application as an engineering plastic. This work investigates the application of azo-boron (AZOB) modified reduced graphene oxide (RGO) intercalated by sodium metaborate (SMB) for simultaneous flame retardant (FR), smoke/toxic fumes suppression and tensile strength enhancement of PLA nanocomposites. The RGO-AZOB/SMB hybrid was prepared by aryl grafting of AZOB on GO followed by in-situ reduction/intercalation with sodium borohydride/SMB. Then RGO-AZOB/SMB hybrid was incorporated into PLA, and the properties were examined. Cone calorimeter test demonstrates improved FR performance by substantial reductions in peak heat release rate ∼76.5%, total heat release ∼76.9%, total smoke release ∼55.6%, peak CO production ∼25.9% and peak CO2 production by ∼78.6%. A V-0 rating was attained in the UL 94 test with a higher LOI value of 31.2%. Considerable reductions in pyrolysis products, mainly hydrocarbons, CO, CO2, and carbonyl compounds were observed. The tensile strength and Young's Modulus were improved by 49.1% and 34.9% respectively. The FR mechanism of RGO-AZOB/SMB/PLA nanocomposites is based primarily on the glassy charring effect of the B–OH groups in AZOB and the inherent lamellar blocking effect of RGO.

Exploring renewable bio-based polymer materials with intrinsic flame retardancy and high mechanical strength will greatly increase the potential to meet fire safety and practicability requirements. In this study, a hexa-substituted cyclophosphazene monomer (HEP) is synthesized from abundant and renewable eugenol and then copolymerized with multi-thiol monomers to establish HEP-SH polymer networks by thiol-ene photopolymerization. Four HEP-SH polymer networks (HEP-TEGDT, HEP-TTMP, HEP-PETMP, HEP-TEMPIC) were prepared by varying the number of thiol groups or the backbone of thiol monomers. Among these polymer networks, HEP-PETMP and HEP-TEMPIC networks exhibit excellent flame retardancy (LOI > 27 vol.%, achieved UL 94 V-0 rating). The combustion parameters and flame retardant mechanism are further studied by cone calorimetry and combined scanning electron microscopy/energy-dispersive spectroscopy (SEM-EDS), which confirm the intumescent flame retardancy of HEP-SH networks is simultaneously affected by the contents of phosphorus and nitrogen element, as well as the structural features of the polymer network. In addition, the HEP-TEMPIC and HEP-PETMP networks also exhibit high mechanical strength and transparency. These eugenol-based thiol-ene polymer networks open a new pathway to develop sustainable high-performance flame retardant bio-based polymer materials for practical application.

A spiro-bisphosphate (MFR) was designed and synthesized via the reaction of spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride (SPDPC) and 2,4-dihydroxybenzophenone (UV-0) with dual functions of flame retardance and ultraviolet absorption. The chemical structure was confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). The flame retardancy performance of MFR was investigated in the commercial epoxy resin E−44 with respect to pyrolysis and fire behavior by thermogravimetric analysis (TGA), limiting oxygen index test (LOI), vertical burning test (UL 94) and cone calorimeter test. The results showed that EP/20%MFR thermoset (EP thermoset with 20 wt% MFR adding) passed the V-0 level in UL 94, and attained a LOI value of 32.2%. The peak heat release rate (p-HRR), total heat release (THR), average effective heat combustion (av-EHC), average mass loss rate (av-MLR) and total smoke release (TSR) of EP/20%MFR thermoset decreased compared with those of neat EP. The flame retardant mechanism of EP/MFR thermoset has been studied in detail. Adding MFR significantly increased char residues and mainly be responsible for the good flame retardancy of MFR. Besides, MFR demonstrated the better UV absorption capability than UV-0.

Dipentaerythritol (DPER), 4, 4′-diphenylmethanediisocyanate (MDI) and melamine (MEL) are used as raw materials to microencapsulate ammonium polyphosphate (MAPP) in situ polymerization. The MAPP is characterized by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA). The results show that the coating operation can effectively improve water resistance of ammonium polyphosphate (APP), and MAPP has higher residual rate than that of APP after combustion. The flame retardant action of MAPP and APP in polypropylene (PP) is investigated by the limited oxygen index (LOI), vertical burning test (UL-94), TGA, SEM, and cone calorimeter test (CCT). The LOI value of the PP/MAPP composite at the same loading is higher than that of PP/APP composite. UL 94 ratings of PP/MAPP composites are raised to V-0 at 20 wt% loading. The results of CCT also show that MAPP is more efficient than APP. The morphological structures observed by digital photos and SEM demonstrated that MAPP could be promoted to form the continuous and compact intumescent char layer. The flame retardant mechanism of PP/MAPP is also discussed.

Sulfenamide based radical generators that contain a nitrogen-sulfur (N-S) core, can alone provide flame retardancy in polypropylene (PP), polyethylene and polystyrene, as we have earlier demonstrated. Herein, sulfenamides potential as synergists with conventional halogen free flame retardants has been explored. Thus, five different sulfenamides were individually combined with selected eco-friendly, phosphorus based flame retardants or aluminium trihydroxide (ATH), and their effect on polypropylene flammability was assessed by limiting oxygen index (LOI), vertical flammability (UL 94 V) and cone calorimeter tests. Thermogravimetric analysis (TGA) and nuclear magnetic resonance (NMR) studies were carried out to detect changes in thermal behaviour when such two component FR systems were mixed together at different ratios. TGA-FTIR (thermogravimetric analysis-Fourier transform infrared spectroscopy) was used to investigate the differences in decomposition products of non-flame retarded versus flame retarded PP. Strong synergistic effects were observed, and the UL 94 V-0 rating was reached for PP with a total FR loading of 10 wt% using 8 wt% of phosphonate ester AFLAMMIT® PCO 900 together with 2 wt% of sulfenamide flame retardant. In a ternary mixture of an additional phosphazene additive (SPB-100), the needed total concentration for V-0 rating was further reduced to 9 wt%. In addition, the combination of 4 wt% of aluminum hypophosphite (AHP) with 0.5 wt% of sulfenamide offered a unique halogen free solution for achieving UL 94 V-2 rating in PP. Cone calorimeter studies of an ammonium polyphosphate-pentaerythritol based intumescent system in combination with 0.5 wt% of sulfenamide also showed encouraging results. The char stability was enhanced, the peak of heat release rate (HRR), CO and CO2 production and total smoke generation were all reduced compared to the reference sample without sulfenamide.

To improve the flame retardancy of polyamide 6 (PA 6), 2,3-dicarboxy propyl diphenyl phosphine oxide (DPDPO) as the reactive flame retardant was introduced into the molecular chain of PA 6. The chemical structure, thermal property, mechanical property and flame retardancy of flame retardant PA 6 were characterized by Fourier Transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, differential scanning calorimetry, thermogravimetric analysis, tensile test, vertical burning test and limiting oxygen index (LOI) test. The flame-retardant mechanism was analyzed by cone calorimetry and pyrolysis-gas chromatography-mass spectrometry. The introduction of DPDPO reduced the melting point and crystallization of flame retardant PA 6, but the flame retardancy of flame retardant PA 6 improved. The flame retardant PA 6 with 5 wt% DPDPO can pass the V-0 rating (UL 94) and the LOI value reach 31.7%. The results indicated that DPDPO promotes the degradation of PA 6 at high temperature, and mainly act by the quenching effect of phosphorus-containing radicals in the gas phase. In addition, the reduction of caprolactam produced during degradation also contributes to the improved flame retardancy. The inherently flame retardant PA 6 shows the prospect in the fields of fiber and textile.

The multicomponent flame retardant system of melamine polyphosphate (MPP), melamine cyanurate (MC) and aluminum diethylphosphinate (AlPi) is proposed and investigated for thermoplastic polyurethane (TPU). The synergy between those additives and the resulting superior fire performance are discussed. Systematically varied sets of flame retarded TPU with various MPP/MC/AlPi ratios were investigated in terms of fire behavior, pyrolysis products and mechanical properties. The total amount of the additives was always 30 wt.-%. Further, the influence of various AlPi concentrations was investigated. The optimal MPP:MC ratio was determined while keeping the amount of AlPi constant. The combination of 8 wt.-% MPP, 12 wt.-% MC and 10 wt.-% is proposed as the most promising halogen free flame retardant formulation for TPU, because it yielded a reduction in PHRR from 2660 kW/m2 (TPU) to 452 kW/m2 and enabled V-0 classification in the UL 94 test. Combinations of MPP and MC as well a high concentration of AlPi are beneficial for the mechanical properties e.g. tensile strength and elongation at break of the formulations and could be a strong competitor to commercial flame retarded TPUs.

Usually elastomers are loaded with high amounts of flame retardants to fulfill fire safety requirements. In this study the potential char precursor polyaniline (PANI) and the established fire retardant pentaerythritol (PER) were implemented in ethylene-propylene-diene monomer rubber (EPDM). PANI and PER were used in low loadings (7 phr) and combined with two phosphorous flame retardants, ammonium polyphosphate (APP) and a piperazine-pyrophosphate/phosphoric acid compound (FP), to boost their performance. A comprehensive study is presented, explaining the impact of PANI on curing and mechanical properties, including compensation for the plasticizer-like effect of APP in EPDM, and improved flame retardancy. In the cone calorimeter test, the combination of EPDM/FP/PANI reduced the effective heat of combustion by 20%. All nine EPDM rubber compounds were investigated with the LOI and UL 94 tests, cone calorimeter, FMVSS 302 and glow wire testing to quantify fire performance. The PANI-containing EPDM rubbers, EPDM/APP/PANI and EPDM/FP/PANI outperformed the corresponding PER containing, EPDM/APP/PER and EPDM/FP/PER rubbers in various tests. Moreover, the study investigated the impact of PANI and PER on the mode of action of the phosphorus species and showed that the addition of PANI increased the amount of phosphorus in the condensed phase. To receive a broader understanding of the flame retardant mode of action of PANI in combination with APP and FP, calculations were carried out to estimate the impact of PANI on the protective layer effect.

In this study, the flame-resistant epoxy syntactic foams with different content of hollow glass microspheres (HGM) were prepared by using aluminum diisobutylphosphinate (AlPBu) as flame retardant. Scanning electron microscope (SEM) images of the fracture surface of different epoxy syntactic foams showed that AlPBu particles had good compatibility with the matrix due to their similar polarities. And the limiting oxygen index, UL 94 test, cone calorimeter and thermogravimetric analysis were applied to characterize the flame retardation and thermal behavior of the foams. These results showed that AlPBu improved the flame retardancy of epoxy syntactic foams, while the HGM exhibit a complicated influence on the flame retardation, although both AlPBu and HGM enhanced the char residues and decreased the peak heat release rate as well as the total heat release of composites. In addition, swollen char layers mainly containing the HGM were generated after adding AlPBu. Then, the char residues of the foams after combustion were observed by SEM, and the results were applied to reveal the different fire behaviors of foams with different densities.

Digital, Housing construction consumes more materials than any other economic activity, with a total of 40.6 Gt/year. Boards are placed between construction materials to serve as non-load-bearing partitions. Studies have been performed to find alternatives to conventional materials using recycled fibers, agro-industrial waste, and protein binders as raw materials. Here, fire-resistant cellulose boards with low density and adequate flexural strength were produced for use as non-load-bearing partitions using waste newspapers, soy protein, boric acid, and borax. A central composite design was employed to study the influence of the board component percentage on flame retardancy (UL 94 horizontal burning test), density (ASTM D1037–12), and flexural strength (ISO 178–2010). The cellulose boards were characterized by thermal analysis (ASTM E1131–14) and scanning electron microscopy. Fire-resistant cellulose boards were successfully made with low densities (120–170 kg/m3) and flexural strength (0.06–0.64 MPa). The mechanical performance and fire resistance of cellulose boards suggest their suitability for use as building materials. A useful and sustainable construction material with great potential is produced with the valorization of waste materials., Ingeniería Ambiental

The biggest obstacle in using the wood as a building material is its lack of resistance against fire. In this study, it is aimed to provide resistance against this big obstacle in using the wood. In this sense, the novel flame-retardant wood composites were produced by using inorganic Turkish huntite and hydromagnesite minerals. For the production of composite material, the mineral was crushed, ground and screened to different sized fractions. Sawdust was used as a composite matrix. First, the mineral additive ratio in the composite was changed by keeping the size value of the additive material constant. Then, the contribution rate was kept constant, but the size values were changed. Hereby, the dependence on quantity and size was investigated. Mineralogical structure was determined by XRF, XRD and SEM-EDS devices. Thermal behavior was observed by the DTA-TG apparatus. Mechanical properties were evaluated by the bending test. UL-94 test apparatus was used to determine the flame-retardant properties of the wood composites. It was concluded that the wood composites, containing inorganic minerals, gain resistance against fire. Besides, the flame-retardant properties of the wood composites were improved as the mineral content increased and the size was reduced.

Recently, lots of effort has been placed into stabilizing black phosphorus (BP) in the air to improve its compatibility with polymers. Herein, BP was chemically functionalized by aliphatic amine (DETA), aromatic amine (PPDA) and cyclamine (Pid) via a nucleophilic substitution reaction, aiming to develop an intensively reactive BP flame retardant for epoxy resin (EP). The -NH2 group on BP-DETA, BP-PPDA and BP-Pid reacted with the epoxide group at different temperatures. The lowest temperature was about 150 °C for BP-DETA. The impacts of three BP-NH2 were compared on the flame retardancy and thermal decomposition of EP. At 5 wt% loading, EP/BP-NH2 all passed UL 94 V 0 rating. The limiting oxygen index (LOI) of EP/BP-PPDA was as high as 32.3%. The heat release rate (HRR) of EP/BP-DETA greatly decreased by 46% and char residue increased by 73.8%, whereas HRR of EP/BP-Pid decreased by 11.5% and char residue increased by 50.8%, compared with EP. Average effective heat of combustion (av-EHC) of EP/BP-Pid was lower than that of EP/BP-DETA and EP/BP-PPDA. In view of the flame-retardant mechanism, BP nanosheets functionalized with aliphatic amine and aromatic amine played a dominant role in the condensed phase, while BP functionalized with cyclamine was more effective in the gas phase.

Mica-type clays nano-dispersed In commodity polymers. These “nanocomposites” exhibit the unusual combination of reduced flammability, in the form of lower peak heat release rates, and However, the details of the fire retardant mechanism are not well understood. In October of 1998 a NIST-industrial consortium was formed to study the flammability of these unique materials. The focus of research within this consortium was to development a fundamental understanding of the fire retardant (FR) mechanism of polymer clay nanocomposites. We report here on some of the results of the first year of this study; we focus our discussions on the results for polystyrene (PS) a polymer system commonly used in flame retarded applications such as information technology (IT) equipment. The most important aspect of the nanocomposite approach is the combined improvement in both clay dispersion. We also report on our recent efforts to address these issues; specifically, our efforts to develop thermally stable immidazolium treated clays, and using solid state NMR to evaluate clay dispersion and alkyl ammonium stability.

The fire behavior of polymers is examined primarily with the time-dependent heat release rate (HRR) measured with a cone calorimeter. The HRR is used to examine the fire behavior of materials with and without flame retardants, especially Polypropylene (PP-Copo) and Polyethylene (PE-LD). Polypropylene is stored for up to 99 days under normal conditions and the heat release rate shows especially changes about 100 s after irradiation with cone calorimeter, which may be caused by aging effects. The effect of crosslinking to the burning behavior of PP was examined too. Polyamides (PA 6) are irradiated with a radiation intensity of 25 kW/m2 to 95 kW/m2 and fire-related principles between radiation intensity and time to ignition can be derived from the measurement results. In order to comprehensively investigate the fire behavior of PP (also with flame retardant additives), the samples were also exposed to a flame, according to UL 94 with small power (50 W) and is inflamed with the power of a few 100 W. The irradiation causes different trigger mechanisms for the flame retardant additives in a plastic than the flame exposure. It is shown that the compound, which is favorable for irradiation, is not necessarily good for flame exposure. It can be seen that expandable graphite alone or with the addition of other additives is a very effective flame retardant for PP.

In the current study, huntite hydromagnesite (HH) was used as flame retardant additive in poly (lactic acid) (PLA) to produce green flame retardant composites. The effects of HH amount, particle size and surface modifications on the flame retardant, thermal and mechanical properties were investigated. The properties of the composites were investigated using limiting oxygen index (LOI), horizontal and vertical burning test (UL 94), mass loss calorimeter, thermogravimetric analysis, tensile test, impact test and dynamic mechanical analysis. According to results, the flame retardant PLA composites with different UL-94 ratings (HB, V2, V0) were produced. The LOI value increased as the added amount of HH increased. The highest LOI value of 34.2 was achieved with the addition of 60 wt% HH. Surface modifications had no remarkable effect on the flammability properties of the composites. The addition of HH reduced the tensile and impact strengths and improved the elastic modulus of the composites as the added amount of HH increased. The addition of HH with large particle size deteriorated the flammability properties and tensile strength despite of the increase in impact strength. Surface modifications improved the mechanical properties of the composites due to the improvement in interfacial adhesion between HH and PLA.

Derivatives of 3,9-dichloro-2,4,8,10-tetraoxa-3,9-diphosphaspiro-[5,5]undecane-3,9-dioxide (SPDPC) are of increasing interest as flame retardants for polymeric materials. In addition, SPDPC is also an important intermediate for the preparation of intumescent flame retardants (IFRs). However, low efficiency and undesirable dispersion are two major problems that seriously restrain the application of IFRs as appropriate flame retardants for polymer materials. Usually, the functionalization or modification of SPDPC is crucial to acquiring high-performance polymer composites. Here, a small molecule spirocyclic flame retardant diphenylimidazole spirocyclic pentaerythritol bisphosphonate (PIPC) was successfully prepared through the substitution reaction between previously synthesized intermediate SPDPC and 2-phenylimidazole (PIM). Phenyl group and imidazole group were uniformly anchored on the molecular structure of SPDPC. This kind of more uniform distribution of flame retardant groups within the epoxy matrix resulted in a synergistic flame retardant effect and enhanced the strength of char layers to the epoxy composites, when compared to the unmodified epoxy. The sample reached a limiting oxygen index (LOI) of 29.7% and passed with a V-0 rating in the UL 94 test with the incorporation of only 5 wt % of as-prepared flame retardant PIPC. Moreover, its peak of heat release rate (pHRR) and total heat release (THR) decreased by 41.15% and 21.64% in a cone calorimeter test, respectively. Furthermore, the addition of PIPC has only slightly impacted the mechanical properties of epoxy composites with a low loading.

A zeolite imidazole framework (ZIF-67) was assembled onto the surface of ammonium polyphosphate (APP) for preparing a series multifunctional flame-retardant APP-ZIFs. The assembly mechanism, chemical structure, chemical compositions, morphology, and specific surface area of APP-ZIFs were characterized. The typical APPZ1 and APPZ4 were selected as intumescent flame retardants with dipentaerythritol (DPER) because of their superior unit catalytic efficiency of cobalt by thermogravimetric analysis. APPZ1 and APPZ4 possessed 6.8 and 92.1 times the specific surface area of untreated APP, which could significantly enhance the interfacial interaction, mechanical properties, and migration resistance when using in ethylene-vinyl acetate (EVA). With 25% loading, 25% APPZ4/DPER achieved a limiting oxygen index value of 29.4% and a UL 94 V-0 rating, whereas 25% APP/DPER achieved a limiting oxygen index value of only 26.2% and a V-2 rating, respectively. The peak of the heat release rate, smoke production rate, and CO production rate respectively decreased by 34.7%, 39.0%, and 40.1%, while the char residue increased by 91.7%. These significant improvements were attributed to the catalytic graphitization by nano cobalt phosphate and the formation of a more protective char barrier comprised of graphite-like carbon.

Enhancement of flame retardancy of a colorless and transparent semi-alicyclic polyimide (PI) film was carried out by the incorporation of phosphazene (PPZ) flame retardant (FR). For this purpose, PI-1 matrix was first synthesized from hydrogenated 3,3&prime, 4,4&prime, biphenyltetracarboxylic dianhydride (HBPDA) and 4,4&prime, oxydianiline (ODA). The soluble PI-1 resin was dissolved in N,N-dimethylacetamide (DMAc) to afford the PI-1 solution, which was then physically blended with PPZ FR with the loading amounts in the range of 0&ndash, 25 wt.%. The PPZ FR exhibited good miscibility with the PI-1 matrix when its proportion was lower than 10 wt.% in the composite films. PI-3 composite film with the PPZ loading of 10 wt.% showed an optical transmittance of 75% at the wavelength of 450 nm with a thickness of 50 &mu, m. More importantly, PI-3 exhibited a flame retardancy class of UL 94 VTM-0 and reduced total heat release (THR), heat release rate (HRR), smoke production rate (SPR), and rate of smoke release (RSR) values during combustion compared with the original PI-1 film. In addition, PI-3 film had a limiting oxygen index (LOI) of 30.9%, which is much higher than that of PI-1 matrix (LOI: 20.1%). Finally, incorporation of PPZ FR decreased the thermal stability of the PI films. The 10% weight loss temperature (T10%) and the glass transition temperature (Tg) of the PI-3 film were 411.6 &deg, C and 227.4 &deg, C, respectively, which were lower than those of the PI-1 matrix (T10%: 487.3 &deg, C, Tg: 260.6 &deg, C)

A series of biobased phosphorus flame retardants has been prepared by converting starch-derived bis-2,5-(hydroxymethyl)furan to the corresponding diacrylate followed by Michael addition of phosphite to generate derivatives with phosphorus moieties attached via P&ndash, C bonds. All compounds behave as effective flame retardants in DGEBA epoxy resin. The most effective is the DOPO derivative, 2,5-di[(3-dopyl-propanoyl)methyl]furan. When incorporated into a DGEBA blend at a level to provide 2% phosphorus, a material displaying a LOI of 30, an UL 94 rating of V0 and a 40% reduction in combustion peak heat release rate compared to that for resin containing no additive is obtained. The analogous compounds generated from bisphenol A and tetrabromobisphenol A exhibit similar flame-retarding properties.

Fires have been a danger to human beings for the centuries. As people lost their lives and property in fires, they tried to fight the fire and their efforts in this area continued increasingly. Unfortunately, it is still not possible to completely reset the risk of starting the fire. But it seems likely to extinguish immediately after the fire has started, and this is very important to save people’s lives. Scientists have been working in this field in recent years; they are concentrated on producing fire-resistant materials using different materials. This can be provided by different ways; either fire-resistant material can be produced new, or the fire resistivity can be provided by incorporating the additive material into a flammable material. In our previous studies, we used huntite and hydromagnesite minerals to give fire resistance property to polymer materials, very successful results were obtained. In this study, huntite and hydromagnesite minerals were used for accompanying with zinc borate in polypropylene composites in order to increase the flame retardant property of a polymeric materials. Different content of minerals were blended with polypropylene, and composites were produced by twin-screw extruder for observing synergistic effect. Scanning electron microscopy (SEM) analyses were conducted to determine the structural and morphological properties of the composites. Thermal properties were determined according to thermogravimetric analysis (TGA). Tensile and three point bending tests were carried out to obtain mechanical properties. Flame retardant performance was evaluated according to UL 94 vertically flammability test. It was concluded that very good synergistic effects were obtained that zinc borate was significantly influential with huntite/hydromagnesite in the flammability characteristics of composites because higher char formation is observed with zinc borate addtion. Moreover, the zinc borate reduced the smoke generated during combustion.

Silica-epoxy nanocomposites were prepared via an “in-situ” sol-gel synthesis process and a phosphorus (P) flame-retardant i.e. 6H-dibenz[c,e][1,2]oxaphosphorin,6-[(1-oxido-2,6,7-trioxa-1-phosphabicyclo[2.2.2]oct-4-yl)methoxy]-, 6-oxide (DP) and melamine (Mel) were further added to the matrix to improve its fire performance. The main components of epoxy resin were bisphenol A diglycidyl ether (DGEBA) and isophorone diamine (IPDA) hardener. The addition of DP as well as silica alone into the epoxy system stopped the melt dripping phenomena in the vertical fire test (UL 94), however, the addition of melamine was crucial for achieving the highest fire classification (UL 94-V0 rating). The presence of DP and Mel in the silica-epoxy nanocomposite promoted a large reduction (ranging from 53% up to 80%) in the heat release rate (HRR) and a delay (up to 31%) in the ignition time in the cone calorimetry experiments. Improved fire performance of the epoxy system was attributed to i) a condensed phase activity of silica, DP and melamine to form a protective thermal barrier during combustion and ii) a minor gas phase flame inhibition activity of DOPO component of DP. The mechanical characterization of the epoxy nanocomposites through tensile tests showed that the addition of DP increases the stiffness of the epoxy resin, resulting in a strong increase of Young modulus (up to 32%) and in a slight decrease of fracture strength, elongation at break and toughness. An increased glass transition temperature (up to 8%) of the epoxy system possibly due to hydrogen bonds and polar interactions of DP with the matrix was also observed.

Bis(1-methoxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate (NORSM) was found to perform an exceptional synergistic effect with tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBPC)/Sb2O3 in HIPS. The LOI of fire retardant HIPS (FR-HIPS) with 16 wt% of TTBPC/Sb2O3 increased from 23.8% to 25.2%, the flame retardant rating of FR-HIPS was improved from UL 94 V-2 to UL 94 V-0, and various heat release parameters such as peak heat release rate, total heat release, and mean effective heat of combustion were greatly lowered by combining NORSM of 0.50 wt%. The Py-GC/MS results revealed that NORSM induced the role of synergistic effect; the main mechanisms were as follows: the active radicals such as methoxy radicals and aminyl radicals produced by the pyrolysis of NORSM promote the release of bromine radicals from TTBPC and the formation of HBr and CO2, which improves the flame retardancy of TTBPC/Sb2O3; the above active radicals, together with HBr, quench active free radicals, such as the hydroxyl radical (OH), and decompose the free radical source, which interrupts the chain reaction during combustion and results in a more efficient flame retardant effect in gaseous phase.

A novel fire-retardant system containing of allylamine polyphosphate/pentaerythritol (AAPP/PER) was used to enhance fire safety of polypropylene (PP). A series of PP with AAPP and PER were mixed via melt blend. Afterwards PP-AAPP/PER system was treated by electron-beam irradiation to increase its thermal stability. The degradation and fire behavior of PP-AAPP/PER system was systematically investigated. The results showed that the LOI testing of PP with 20 wt %AAPP/PER was greatly increased and passed UL 94 vertical testing V-0 rating level. Moreover, the cone-calorimeter testing showed that heat release, smoke produce as well as toxic gases production of PP-AAPP/PER system largely decreased. Incorporation of PER and AAPP was very efficient for enhancing the fire safety of PP composites due to relatively more compact of char residues. Moreover, the sustainable electron-beam irradiation without any use of thermal stabilizers was used to improve the thermal performance of PP-AAPP/PER system.

We present the development of a high-performance flame-retardant vinyl ester (FR-VE)/flax fabric (FF) biocomposite through a hybrid approach using vacuum-assisted resin transfer molding. FF was modified to form FR fibers (mFF) using surface treatment with varying amounts (5–20%) of ammonium polyphosphate (APP), and the FR-VE/mFF composites were fabricated by including flame retardants such as chitosan (CS), APP, and modified CS (NCSAPP). The optimized mFF (15% APP) exhibited enhanced thermal stability (38 wt% residue at 700 °C) and it achieved a V0 rank in the UL 94 test. In addition, the dual effects, i.e., the effects modification of the reinforcement and inclusion of the FRs into the matrix, improved the properties of the FR-VE/mFF composites, providing them with high thermal resistance (28 wt% residue at 700 °C), and fire resistance (V0 rank in the UL 94 test), and self-extinguishing characteristics with a suppressed peak heat release rate (69%), total heat release, and smoke production rate.

A phosphorous–nitrogen containing cyclophosphazene derivative intumescent flame retardant with branched structures, named six(1-oxo-2,6,7-trioxa-1-phosphabicyclo[2,2,2]octane-4-methyl) cyclotriphosphazene (PEPAP), was synthesized by introducing caged phosphate to cyclotriphosphazene backbone. Then the PEPAP was applied to polypropylene (PP) by melt blending to improve the flame retardancy and thermal stability. Fourier transform infrared spectroscopy and proton nuclear magnetic resonance (1HNMR) were used to confirm the chemical structure of PEPAP. Thermal stability and flammability properties of PEPAP and PEPAP/PP composites were investigated by thermogravimetric analysis, limited oxygen index (LOI), vertical burning test (UL-94) and cone calorimetry tests. The flame-retardant mechanism was explored by thermogravimetric analysis/infrared spectrometry and thermogravimetry/mass spectrum analysis. The results showed that PEPAP had high thermal stability, and the addition of PEPAP greatly enhanced the carbonization process of PP. Also, the addition of PEPAP can dramatically improve the LOI value and UL 94 rating. For the 25% PEPAP/PP sample, the LOI value was increased to 29.4% and it can pass UL 94 V-0. The intumescent chars with an intact, multicellular structure formed from PEPAP/PP composites contain polyphosphoric acid, indicating a condensed flame-retardant mechanism of PEPAP.

The rapid mass calorimeter (RMC) was used as a screening tool based on accelerated fire testing to assess flame-retarded thermoplastic polyurethane (TPU). The reliability of RMC results was proven with the cone calorimeter as reference fire test. The influence of melamine cyanurate (MC) concentration on the fire performance of TPU was investigated, along with some flame-retardant combinations such as MC with aluminium diethylphosphinate (AlPi), aluminium trihydrate (ATH), and melamine polyphosphate (MPP). The two-stage burning behaviour of TPU was investigated in detail; the first stage corresponds mainly to the hard segments' decomposition and has a much lower effective heat of combustion (EHC) than the second stage, in which mainly the soft segments decompose and an intensive liquid pool fire is observed in the cone calorimeter set-up. In addition to fire testing with the cone calorimeter, RMC, and UL 94 flammability tests, the decomposition of the materials was investigated using thermogravimetric analysis coupled with infrared spectrometry (TGeFTIR). TPU/MC/AlPi shows the most promising results, achieving V-0 classification in UL 94 and reducing the extreme peak heat release rate (PHRR) of the liquid pool fire from 3154 kW/m2 to 635 kW/m2. Using MC/AlPi/MPP enhances the latter PHRR reduction further. The decomposition products identified in the gas phase via TGeFTIR reveal specific MCeAlPi eMPP interactions, as they differ from products seen in systems with MC/AlPi or MC/MPP. Correlations between RMC and cone calorimeter results were examined and presented in the final part of the paper. Several characteristics correlate strongly, pointing out that RMC is a reliable high-throughput fire testing method to screen multicomponent flame-retardant solutions in TPU.

Incorporation of 10 wt% 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) in polybutylene succinate (PBS) showed a significant improvement of fire behavior at the UL-94 test (3.2 mm): (i) V-0 rating and no ignition of the bar for PBS/DOPO with dripping but with no ignition of the cotton whereas (ii) no classification for neat PBS with dripping and with ignition of the cotton. To fully understand these two different phenomena, an optimized UL-94 instrumentation was developed. Thermocouples embedded in the bar measures heat gradient and infrared (IR) camera equipped with a specific filter permits estimating heat gradient in the bar and surface temperature of the falling drop respectively. The main advantage of this optimized UL-94 instrumentation is to get measurement in situ and in dynamic. This instrumentation has successfully captured the temperature evolution of a falling drop during a UL-94 test. It was shown that the drops of neat PBS exhibits a constant temperature of 453 ± 10 °C when detaching the bar. However the drops' temperature of PBS/DOPO varied during the UL-94 test when they detach the bar: the drops formed at around 403 ± 10 °C at the end of the first ignition, whereas at the end of second ignition they detach the bar at about 313 ± 15 °C. Neat PBS exhibited temperature at least 50 °C higher than PBS/DOPO when the drops touched the cotton: 435 ± 5 °C for neat PBS at the end of first ignition vs. 385 ± 10 °C for the PBS/DOPO at the end of first ignition vs. 295 ± 15 °C for the PBS/DOPO at the end of second ignition. This can explain why the drops of PBS can ignite the cotton whereas those of PBS/DOPO cannot. Additionally, IR camera images indicate the change of rheology by incorporation of DOPO into PBS. A measurement of viscosity by the rheometer showed that PBS/DOPO has lower viscosity than neat PBS.