Ammonium Polyphosphate Content Research Articles

Synthesis, characterization, and swelling properties of a novel tapioca-g-Poly(Acrylic acid−2−acrylamido−2−methylpropane sulfonic acid)/ammonium polyphosphate superabsorbent polymer

In this study, a novel superabsorbent polymer tapioca starch-g-poly(acrylic acid-2-acrylamido-2-methylpropane sulfonic acid)/ammonium polyphosphate (TS-g-AA-AMPS/APP) was synthesized based on the graft copolymerization of tapioca starch (TS) with acrylic acid (AA) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) via free radical polymerization in aqueous solution with ammonium polyphosphate (APP) additive added for study. The synthesized superabsorbent polymer material was characterized by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), energy-dispersive x-ray spectroscopy (EDS), and thermogravimetric analysis (TGA). Research investigating the material synthesis conditions to absorbance in distilled water and 0.9 wt% NaCl solution has also been studied. Under optimal synthesis conditions, the absorbance in distilled water and 0.9 wt% NaCl solution were 416 g g−1 and 61 g g−1, respectively, for the sample with 3 wt% APP content. The introduction of APP units has improved the absorption properties of the material such as the water retention capacity reaching 55.25% in 10 h at 60 °C. TS-AA-AMPS/APP exhibits reversible swelling ability, with the swelling level not being reduced compared to the initial after 5 swelling-drying cycles at 60 °C, and water absorption reaches swelling equilibrium after about 270 min. Additionally, TGA thermogravimetric analysis results showed an improvement in the thermal stability of TS-AA-AMPS/APP compared to the pure polymer. These results show that the TS-AA-AMPS/APP polymer with excellent swelling properties, low production cost, and environmentally friendly has the potential for practical applications in agriculture, gardening, and water retention materials.

Research on flame-retardant paper prepared by the method of in-pulp addition of ammonium polyphosphate

At present, the production of flame-retardant paper usually uses the impregnation method of phos-phorus-nitrogen flame retardants in paper. There are few reports on the application of an in-pulp addition method. In this paper, the solubility of ammonium polyphosphate (APP) and its effect on flame-retardant paper were investigated for use in an in-pulp addition method. It was found that APP particles were square, with an average particle size of 21.88 μm. The particle size decreased significantly after immersion in water at 25°C for 24 h. Furthermore, most of the APPs were dissolved after immersion in water at 90°C for 0.5 h, and the residuals agglomerated and their shape turned into an amorphous form. The APP possessed strong electronegativity and could partially ionize in water. The solubility of APP was 0.18 g/100 mL water at 25°C and increased quickly when the temperature was higher than 30°C. Therefore, APP should be added to the pulp at temperatures below 30°C. The tensile strength of the paper initially increased with the addition of APP, and it reached the maximum value when the APP content was 10% and then gradually decreased. The limiting oxygen index (LOI) value of the paper was 28.7% when the added amount of APP was 30% and cationic polyacrylamide (CPAM) was 0.08%, reaching the flame-retardant level.

Enhanced flame resistance of cellulose aerogel by ammonium polyphosphate for heat insulation

Cellulose aerogels are a potential candidate for heat insulation, but one of their drawbacks is high flammability hindering their applications in practice. This study synthesized cellulose aerogels from microfibrillated cellulose fibers (MFC) extracted from discarded pineapple leaves. The procedure started with simply mixing the extracted fibers with polyamide amine-epichlorohydrin (PAE) as a chemical crosslinker and ammonium polyphosphate (APP) (10-20%) as a green and effectively flame-resistant additive, followed by freeze-drying. The produced aerogels are characterized in terms of their morphology, thermal stability and conductivity, and flame resistance via advanced and standardized methodologies including Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TGA), thermal conductivity measurement by a heat flow meter, and UL94 horizontal burning test. The flame-resistant cellulose aerogels exhibit ultra-low density (25.5-26.8 mg/cm3), high porosity (98.0-98.2%), excellent heat insulation (35.9-36.7 mW/m۰K), and are completely flame-resistant. In addition, the varied APP content (10-20%) shows little effect on the density, heat conductivity, and thermal stability of the flame-resistant cellulose aerogels in comparison with that of the neat cellulose aerogel. Based on the findings, the synthesized flame-resistant cellulose aerogels are considered a promising bio-based heat insulation material.

Polyelectrolyte Complex with Controllable Viscosity by Doping Cu2+ Protects Nylon-Cotton Fabric against Fire.

Nylon-cotton (NC) blend fabrics are widely used in military and industrial applications, but their high flammability still remains a serious problem. In an effort to effectively and quickly impart flame retardancy to the NC fabric, it was treated by simply blade coating with a Cu2+-doped polyelectrolyte complex (CPEC) that consists of ammonium polyphosphate (APP), polyethylenimine (PEI), and copper sulfate. The viscosity of the CPEC can be adjusted by altering the content of CuSO4, which controls the amount of extrinsic and intrinsic ion pairs. By adjusting the proportion and content of PEI, APP, and CuSO4, CPEC suitable for treating the NC fabric was obtained. Only 0.067 wt % Cu2+ was needed to adjust the viscosity and impart self-extinguishing behavior in a vertical burning test. This simple two-step treatment provides a promising technology to protect flammable polymeric substrates with ultralow metal-doped polyelectrolyte complexes.

Bio-based poly (glycerol-itaconic acid)/PEG/APP as form stable and flame-retardant phase change materials

With the improvement of people's living level, smart home and comfortable life put forward novel and highly scientific requirements for building materials and home environment. Environmental protection, renewability, processing convenience and use safety (non-toxic/fire safety) are all core indicators that need to be considered in an all-round way in the process of material design. In this work, we used a simple and efficient green process by blending ammonium polyphosphate (APP) and poly (glycerol-itaconic acid) loaded polyethylene glycol (PEG) to prepare fire safe phase change materials (PCMs). The flame retardancy, phase change performance and thermal response behavior (including form stability, thermal conductivity, cycle stability, and latent heat etc.) were systematically characterized. The results showed that limiting oxygen index (LOI) increased significantly with the increase of APP content. Typically, when the filling amount of APP reached 15 wt%, the LOI value increased from 21.6% to 28.7%, vertical testing reached UL-94 V0 rating and the pHRR decreased by 36.15%. The as-prepared PCMs show excellent form stability, and the enthalpy of phase change keeps higher than 70 J g−1, which is at the high level as that of same kinds of PCMs. Notably, due to its high preparation efficiency for PCM fabrication and the profiles of all bio-based supporting matrix, solvent-free pathway, mild curing temperature, and fire safety, it is expected to be effectively applied in building for the thermal regulation.

Development and optimization of fire-protective coating composition based on epoxypolymers

The object of research is intumescent fire retardant coatings based on epoxy resins. The research is aimed at the development of mathematical models of the dependence of the swelling rate of intumescent fire retardant coatings on their composition. Considering the complexity of the processes during the formation of a protective carbon layer, it is advisable to select the optimal ratio of the components of an intumescent fire retardant coating experimentally, followed by the construction of mathematical dependences of the swelling ratio on the coating composition. Therefore, experimental studies aimed at developing and optimizing the composition of an intumescent fire retardant coating based on epoxy polymers are an important task. The studies were carried out in accordance with the theory of planning experiments with the construction of an orthogonal compositional plan of the second order. A linear swelling factor was chosen as the response function. Compositions based on the ED-20 epoxy oligomer, cured with polyethylene polyamine and filled with ammonium polyphosphate, aluminum hydroxide, and graphite additive were used for the study. Based on the results of processing the experimental results, a regression equation was obtained and response surfaces were constructed that describe the dependence of the linear swelling coefficient Cs of an intumescent composition based on an epoxy oligomer on the content of ammonium polyphosphate, aluminum hydroxide and graphite additive. A complex relationship is shown between the content of components and the linear swelling coefficient Cs with different ratios of the components. The optimum by the linear swelling coefficient (Cs=68.1) content of the components in the epoxy polymer was determined, amounting to 20 wt. including for ammonium polyphosphate, 15 mass parts including for aluminum hydroxide and 3 mass parts for the graphite additive. However, with such a ratio, the «self-extinguishing» condition is not met (Cs=27 %). Filling the composition with ammonium polyphosphate in an amount of 26.3 mass parts including, aluminum hydroxide 25 mass parts and 3.5 mass parts including graphite additives allows to get an intumescent fire retardant coating with a swelling ratio Cs over 63 and a reduced level of flammability (Ci=31 %)

Preparation of ammonium polyphosphate and dye co-intercalated LDH/polypropylene composites with enhanced flame retardant and UV resistance properties

In this paper, ammonium polyphosphate (APP) with flame retardant performance and acid red 88 (AR88) with UV absorption property were intercalated into layered double hydroxide (LDH) interlayers together, aiming to improve the flame retardancy and UV resistance properties of polypropylene (PP) simultaneous in one system. The synthesized LDHs and PP/LDH composites were characterized systematically and the results showed that AR88 and APP were intercalated into LDH interlayers successfully, and the content of APP and AR88 in LDH interlayers can be controlled through the synthesis process. Both APP-LDHs and AR88/APP-LDHs can greatly improve the flame retardancy performance of PP, with 25 wt% LDH addition, the peak heat release rate (PHRR) decreased by 42–63%, respectively. Temperature at 50% mass loss (T50) of PP also increased to some extent. In addition, the intercalation of AR88 in LDH also possessed good UV adsorption which can delay the ageing of PP during their use. Thus, a new approach to improve both flame retardant and UV resistance properties for polymers at the same time is achieved.

Dual-functional intumescent fire-retardant/self-healing water-based plywood coatings

Water-based fire-retardant coatings for wood are non-toxic, aesthetically pleasing, and can provide appreciable fire retardancy properties. However, excessive fire-retardant content and simple fire-retardant function limit their practical application. In this work, a semi-interpenetrating network (SIPN) technique was used to prepare a semi-transparent dual-functional, intumescent fire-retardant/self-healing water-based coating for plywood. The coatings comprised ammonium polyphosphate (APP) as a source of acid source and gas source; poly (vinyl alcohol) (PVA) as the carbon source and self-healing agent; and sodium silicate and sodium fluorosilicate (SS) as precursors for forming an integral inorganic network. Our semi-transparent coatings demonstrated excellent fire retardancy thanks to the interplay between the inorganic silicate network and the intumescent fire-retardant system. Remarkable self-healing properties were provided by the dynamic hydrogen bonding interaction between PVA molecular chains, where significant scratches were healed after exposure to water vapor. The PVA/SSA coating enhanced the fire retardancy of plywood, which was shown to be directly related to the APP content. The combination of semi-transparent, fire-retardant and self-healing capabilities underlines the potential of our PVA/SSA coatings for protecting and safeguarding wooden products.

Using scanning electron microscopy, x-ray diffraction and IR spectroscopy to study the ageing of intumescent fire-proof coatings

Introduction. The fire protection of metal structures is a relevant present-day problem; its solution implies better fire resistance performance of structures attainable through the application of intumescent fire-proof coatings whose service life expectancy is limited.Goals and objectives. Comprehensive studies of domestically made coating samples were performed to analyze the changes in the chemical composition of intumescent coatings containing ammonium polyphosphate, melamine, and pentaerythritol. The samples were exposed to artificial climatic ageing (3, 6, and 9 years). Methods. Optical and scanning electron microscopies were used to study the appearance of samples, the morphology of inclusions and the surface microstructure. X-ray diffraction and IR spectroscopy were employed to study the phase and structural states of samples, and the swelling ratio of fire-proof coatings was also examined.Results and discussion. It’s been found out that the swelling ratio of samples goes down to a significant extent as the time progresses, and when the residual life of a coating reaches 30 %, the fire resistance limit of the structure goes down. Sample ageing is the reason for gradual phase composition changes due to the melamine content reduction by 40 %, ammonium polyphosphate content reduction by 15 % and redistribution of other components that change the microstructure of coatings, as well as their fire retarding properties.Conclusions. The changes, influencing the ability of a coating to maintain its fire retarding efficiency as declared by the manufacturer, take place in the course of operation of a coating exposed to external factors. The regularities, identified by virtue of this research, can be used to study the samples taken at fire-proofed facilities to identify deviations from the initial condition of a coating and to forecast its actual service life.

Fire‐retardant carbon/glass fabric‐reinforced epoxy sandwich composites for structural applications

AbstractIn this study, the fire‐retardant performance of lightweight sandwich composites, with modified epoxy impregnated carbon and glass fabric reinforcements and an aluminum honeycomb core, is investigated. The fire‐retardant performance of the fabricated sandwich composites is improved by treating carbon fiber reinforcements with phosphoric acid, and by impregnating the epoxy matrix with different loadings of ammonium polyphosphate (APP) fire‐retardant additive. The laboratory aging behavior of sandwich composites is also carried out to further investigate the degradation resistance of the panels under extreme conditions. Fire and mechanical properties of epoxy and sandwich panels are investigated using UL‐94, limiting oxygen index (LOI), thermal gravimetric analysis, compression tests, and three‐point bending tests. In the case of sandwich composites, a maximum of 1345 and 45.2 MPa flexural and compression modulus, respectively, are achieved with 10 wt% APP content in epoxy. Maximum 30% and 33% LOI values are achieved with 10% APP content in the epoxy and sandwich panels, respectively.

Simultaneously enhanced fracture toughness and flame‐retardant property of poly(l‐lactic acid) via reactive blending with ammonium polyphosphate andin situformed polyurethane

AbstractThe preparation of poly(l‐lactic acid) (PLLA) with high mechanical and ideal flame‐retardant properties is a great challenge. Herein, a simultaneous toughness and flame‐retardant PLLA composite was successfully fabricated by using a one‐step process which introduces 4,4′‐methylenediphenyl diisocyanate and ammonium polyphosphate (APP) into PLLA/poly(ε‐caprolactone) blends. SEM, Fourier transform infrared spectroscopy and TGA were adopted to confirm that APP participated in thein situreaction during the melt process. The impact strength was increased to 13.5 kJ m−2from 1.0 kJ m−2for L8P2A5 composite, indicating the toughening effect of reactive blending. The cone calorimeter test, limiting oxygen index and vertical burning test results indicate that the flame‐retardant properties of the composites are enhanced with increasing APP content. This work provides a method to prepare PLLA with high mechanical properties and enhanced flame retardancy. © 2020 Society of Chemical Industry

Synergistic effect of hierarchically porous 4A zeolite on improving the fire retardancy and reducing the fire toxicity of ammonium polyphosphate treated wood composites

The synergistic effect of hierarchically porous zeolites on the fire retardancy and fire toxicity of ammonium polyphosphate (APP) treated wood composites was studied in this work. Hierarchically porous 4A (H4A) zeolite and 4A zeolite were hydrothermally synthesized and characterized. Several groups of wood composites containing APP as fire retardant and H4A/4A zeolites as synergists were fabricated. Thermogravimetric (TG) results showed that H4A zeolite increased the char formation and enhanced the thermal stability of APP treated wood at higher temperature. Cone calorimetry test results suggested that H4A zeolite reduced the heat release rate (HRR) and decreased CO produce rate (COPR) of APP treated wood composites. Moreover, H4A also exhibited better smoke suppression than 4A zeolite when the APP content was small. These results demonstrated that H4A zeolites may be a promising synergistic component for improving the fire retardancy and reducing the fire toxicity of APP treated wood composites.

Synergistic Flame Retardant Effects of Expandable Graphite and Ammonium Polyphosphate in Water-Blow Polyurethane Foam

In this research, expandable graphite (EG) and ammonium polyphosphate (APP) were incorporated into water-blow semirigid polyurethane foam (SPUF) as flame retardants. The synergistic flame retardant effects of EG with APP in SPUF had been studied by thermogravimetric analysis (TGA), limiting oxygen index (LOI), horizontal burning test, polarizing microscope, and scanning electron microscopy (SEM). The results indicated that APP and EG used together in SPUF could effectively improve the flame retardancy of SPUF. When the EG to APP ratio reached 2 : 1 under the total content of flame retardants was kept constant as 20%, the LOI value was increased by about 51% compared to pure SPUF, 2.9% to SPUF/EG and 16.3% to SPUF/APP. Besides, the residual char was increased up to 27.7% displayed by TG test results. SEM shows that burned residues of EG/APP/SPUF present more compact char and worm-like structure. Furthermore, EG shows negative effect on the mechanical property of SPUF with 21.7% decrease in compression modulus, but the mechanical property can be improved by the addition of appropriate content of APP.

Vanillin‐derived phosphorus‐containing compounds and ammonium polyphosphate as green fire‐resistant systems for epoxy resins with balanced properties

Flame retardants from vanillin when utilized together with ammonium polyphosphate (APP) yield excellent synergistic flame retardancy toward epoxy resins. Bisphenol A epoxy resins have been widely used due to their excellent mechanical properties, chemical resistance, electrical properties, adhesion, etc., while they are flammable. Environment‐friendly and bio‐based flame retardants have captured increasing attention due to their ecological necessity. In this paper, 3 bio‐based flame retardants were synthesized from abundant and more importantly renewable vanillin, and their chemical structures were determined by 1H NMR and 13C NMR. They were used together with APP (an environment‐friendly commercial flame retardant) to improve the fire resistance of bisphenol A epoxy resin. With the addition APP content of 15 phr, the modified bisphenol A epoxy resin could reach UL‐94V0 rating during vertical burning test and limit oxygen index values of above 35%, but reducing APP content to 10 phr, the flame retardancy became very poor. With the total addition content of 10 phr, the epoxy resins modified by 7 to 9 phr APP and 1 to 3 phr bio‐based flame retardants with epoxy groups or more benzene rings showed excellent flame retardancy with UL‐94V0 rating and limit oxygen index values of around 29%. The Tgs of the epoxy resins could be remained or even increased after introducing bio‐based flame retardants, as the control; those of APP alone‐modified epoxy resins compromised a lot. The green synergistic flame‐retardant systems have a great potential to be used in high‐performance materials.

Polyurethane coatings based on linseed oil phosphate ester polyols with intumescent flame retardants

SummaryThe effect of intumescent flame retardants on the properties of polyurethane (PU) coatings based on 2 kinds of phosphate ester polyol was studied. Synthesizing polyols, phosphorylation of epoxidized linseed oil with phosphoric acid was performed in the presence of isopropyl alcohol (IPA polyol) or diethylene glycol butyl ether (DGBE polyol). The obtained polyols were characterized by Fourier transform infrared (FTIR) and 31P nuclear magnetic resonance (NMR) spectroscopy. The properties of neat PU coatings based on 2 polyols and those filled with different content (up to 25 wt%) of melamine (Mel), ammonium polyphosphate (APP), and expandable graphite (EG) were studied using thermal gravimetric analysis (TGA), and tensile and cone calorimeter tests. It was found that IPA polyol contained not only phosphate monoesters and diesters, as DGBE polyol, but also phosphate triester and pyrophosphate monoester. Due to this difference, IPA neat and filled coatings had higher tensile characteristics and char residue in a TGA test. Also, the flame retardancy of IPA coatings, compared with that of DGBE coatings, was higher. In a cone calorimeter test, coatings filled with Mel showed a small increase of flame retardancy, but the total smoke release (TSR) of wood samples with coatings decreased noticeably. The effect of APP on the flame retardancy of coatings was higher, but in contrast, the TSR of samples increased with increasing APP content. Even greater decrease of flammability parameters and a simultaneous significant decrease of TSR were shown by the samples with IPA coatings filled with EG.

Development of fire resistant coating for the protection of electrical cables of fire in a closed space

The object of research is the composition of the fire-resistant swelling coating. The main problem of electric cables fire protection in a confined space is a high concentration of toxic substances in the composition of combustion products, which makes it difficult fire extinguishing works. This is due to the fact that the cables polymer insulation (polyethylene, polyvinyl chloride) and traditional flame retardant coatings based on epoxy and phenolic resins contain potentially hazardous substances. These substances during combustion are form toxic compounds (chlorine, carbon monoxide, hydrogen cyanide). Experimental studies of various compositions based on the silicone resin were carried out to solve the problem of creating a non-toxic fire-resistant swelling coating. This has allowed to develop optimal recipe of fire-resistant coating the components of which do not emit nontoxic substances under fire conditions. The original test procedure for coatings for fire resistance, with exposure to samples of the open flame of a gas burner was applied during the study that is more consistent with the conditions of a real fire. The temperature on a back surface of the sample was controlled during the experiments. The functional dependence of the fire-resistant properties of coatings on the concentration of components was obtained The optimal composition of the fire-resistant swelling coating was obtained, which contains: ammonium polyphosphate 65±2 %; pentaerythritol – 1 5 ±2 %; melamine – 1 0 ±2 %; aluminum and magnesium hydroxides – 5±1 % by fine fillers weight. The proposed composition of the fire-resistant coating content has an increased content of ammonium polyphosphate, which mainly determines the good flame retardant properties. The developed composition as a whole meets the requirements for fire resistance and has advantages over similar fire-resistant compounds in terms of toxicity level.

Effect of zeolites on morphology and properties of water-blown semi-rigid ammonium polyphosphate intumescent flame-retarding polyurethane foam

Water-blown semi-rigid polyurethane foams (SPFs) were prepared by a one-shot, free-rise method. Effect of zeolites (ZEO) on morphology, flame retardancy, mechanical properties, damping properties, and thermal properties of ammonium polyphosphate (APP) intumescent flame-retarding SPFs was studied through the analysis of rotary viscosity test, limiting oxygen index (LOI), horizontal-vertical burning test, scanning electron microscopy (SEM) and mechanical test etc. Rotary viscosity test found that viscosity just enhanced a little when zeolites were added to the reaction matrix containing APP. With zeolites added, internal defects foams caused by the high loading of flame retardants could be effectively eliminated because the reaction heat could be partly taken by zeolites’ crystal water. The addition of zeolites did not increase the density of the APP intumescent flame-retarding SPFs. Meanwhile, with the presence of zeolites the APP intumescent flame-retarding SPFs exhibited better flame retardant property when APP content is high. Mechanical test showed that with the introduction of ZEO, compression strength and compression modulus of SPFs stably enhanced with the increasing APP loading and reached a maximum value when the APP content was 45 pphp. At a certain ZEO content (ZEO = 15 pphp), the APP intumescent flame-retarding SPFs with zeolites exhibited higher compression strength and modulus when the APP loading was over than 45 pphp.

Effects of ammonium polyphosphate content on mechanical, thermal and flammability properties of kenaf/polypropylene and rice husk/polypropylene composites

This study investigated the effects of ammonium polyphosphate (APP) content on the mechanical, thermal and flammability properties of kenaf/polypropylene (KF/PP) and rice husk/polypropylene (RH/PP) composites prepared by melt mixing technique. Polyethyleneoctene grafted maleic anhydride (POE-g-MAH) has been used as compatibilizer. The PP/KF/APP and PP/RH/APP composites were investigated using flexural and impact tests, scanning electron microscope, thermogravimetric analysis (TGA), differential scanning calorimeter and limiting oxygen index (LOI) test. Flexural modulus of PP/KF/APP and PP/RH/APP composites significantly improved from approximately 1.1–2.5 and 0.9–2.1GPa, respectively, by the addition of 10phr APP. The flexural strength of the composites also increased by the incorporation of 10phr APP. In addition, the impact strength of the PP/RH/APP composites increased above 10phr APP content. From the TGA results, incorporation of APP into PP/RH and PP/KF composites increased the char residue and thermal stability of the composites. Furthermore, the addition of APP increased the flame retardancy of the PP/KF/APP and PP/RH/APP composites with a significant increase of LOI at 10phr.

Development of fire resistant wool polymer composites: Mechanical performance and fire simulation with design perspectives

Wool, as a naturally fire resistant fibre, has been incorporated with other additives, such as ammonium polyphosphate (APP), talc and maleic anhydride grafted polypropylene (MAPP), to manufacture polypropylene (PP) based composites. A single-screw extruder, attached with a flat die, has been used to successfully produce continuous wool-PP composite sheets. Furthermore, the significant roles of nitrogen content of APP and the talc in forming the effective char to increase the composites' fire retardancy have been identified through cone calorimeter tests. In particular, it is highly interesting to note that a reduction of APP content from 20 to 15wt% was possible to achieve a direct self-extinguishment (V-0 rating) of the composite. The decrease in APP amount has also led to the reduction of material cost due to APP's relatively high price (USD 13–14/kg) and limit the possibility of deteriorating mechanical properties due to APP addition. The MAPP has enhanced thermal stability and mechanical properties compared to those without the additive, which could be attributed to the improved interfacial adhesion between wool and PP. A computational fluid dynamics model has also been developed by Fire Dynamics Simulator to mimic the cone calorimeter tests, which agreed reasonably well with the experiments.

Effect of Ammonium Polyphosphate on Flame Retardancy, Thermal Stability, and Mechanical Properties of Unsaturated Polyester/Phenolic/Montmorillonite Nanocomposites

ABSTRACTIn present research, the effect of ammonium polyphosphate (APP) content on flame retardancy, thermal stability, and mechanical properties of unsaturated polyester resin/unsaturated phenolic resin/montmorillonite (MMT) nanocomposites were studied. Nanocomposites were prepared via in situ mold casting technique. Flame retardancy of the nanocomposite was investigated through the UL 94 vertical burning test and limiting oxygen index (LOI) analysis. Thermogravimetric analysis (TGA) was conducted to measure thermal properties, whereas flexural and impact tests were carried out to determine mechanical properties of nanocomposites. Nanocomposites with 30 phr APP achieved the flammability rating of V‐1 and LOI of 29.2%. TGA results showed that nanocomposites with 30 phr APP had the highest thermal stability. Nanocomposite prepared with 3 phr MMT had the highest flexural strength, flexural modulus, and impact strength. Thus the best balance between flame retardancy, thermal stability, and mechanical properties was achieved with MMT and APP content of 3 and 30 phr, respectively.