Modified Ammonium Polyphosphate Research Articles

Interface engineering of multi-component core-shell flame retardant towards enhancing fire safety of thermoplastic polyurethane and mechanism investigation

Polymeric materials usually present substantial hazards to human health and the environment as a consequence of their flammability which leads to the emission of a great deal of heat and toxic fumes. To address this issue, it is imperative to urgently enhance the flame retardancy of polymer materials. This study focuses on the synthesis of a novel gel-silica/polydopamine double-layer microencapsulated cobalt ions (Co2+) modified ammonium polyphosphate (APP-Co@PDA@Si) and its utilization in thermoplastic polyurethane (TPU) composites. The resulting TPU composite, containing 10.0 wt% APP-Co@PDA@Si, exhibited excellent flame-retardant properties, i.e. achieving a limiting oxygen index of 30.0 % and the V-0 grade in the UL-94 test. Furthermore, peak heat release rate, total heat release, peak smoke production rate, and total smoke release of the TPU composite were decreased by 88.51 %, 66.06 %, 61.73 %, and 74.01 %, respectively, in comparison to those of pure TPU. The enhanced fire safety of the TPU composite was attributed to the synergistic effect among Co2+ catalytic carbonization, the free radicals capture effect of APP, and the flame-retardant functions of PDA and silane. This innovative strategy proposed in this work holds great promise for improving the fire-resistance of TPU.

Chemical, pyrolysis, combustion properties and mechanism analysis of wood treated with biomass-based carrageenan-collagen modified ammonium polyphosphate

Biomass-based flame retardants are characterized by readily available raw materials and are environmentally friendly, making the design of green and efficient biomass-based flame retardants a critical direction in the development of flame-retardant technology. In this study, a novel biomass-based flame retardant (Acc) was developed using ammonium polyphosphate (APP) as a raw material in combination with the biomass materials carrageenan (CAR) and collagen (COL). Flame-retardant wood was prepared via ultrasonic impregnation. Via various analytical and testing methods, such as the Limiting Oxygen Index (LOI), thermogravimetric analysis, scanning electron microscopy, Raman spectroscopy, cone calorimetry, and thermogravimetric–infrared coupling, the combustion performance of biomass-based flame retardants on wood was investigated to elucidate the flame-retardant mechanism. The results indicated that the flame retardant with a CAR:COL:APP ratio of 1:1:3 exhibited the best flame-retardant effect, with an LOI of 31.8 %. The peak heat release rate was reduced to 53.8 % compared with that of untreated wood, and both the peak smoke release rate and total smoke release were reduced by 63.2 % and 49.2 %, respectively, demonstrating a significant smoke-suppression effect. Analysis of the mechanism revealed that APP, COL and CAR generated non-combustible gases such as ammonia and gases containing P and S when exposed to fire. These gases dilute oxygen and eliminate •H and •HO radicals in the gas phase, thereby exerting flame-retardant effects. Acc promotes the formation of a dense crosslinked carbon layer containing N=C, N-C/P-N, N-H, and C-O-P. This carbon layer acts as a physical barrier, isolating oxygen (O2), blocking gas emissions, and slowing heat exchange. This study provides a new avenue for the development of green and sustainable flame retardant wood.

Facile construction of polypyrrole microencapsulated γ‐Fe2O3 for simultaneously enhancing the flame retardancy and smoke toxicity suppression of intumescent flame‐retardant epoxy resins

AbstractFor effectively strengthening the comprehensive properties of intumescent flame‐retardant epoxy resins (EPs), a microencapsulating γ‐Fe2O3 by polypyrrole (PPy) named PPy‐Fe2O3 was synthesized and used as a synergist to simultaneously enhance the flame retardancy, smoke toxicity suppression and mechanical strength of EP composites containing diaminodiphenylmethane modified ammonium polyphosphate (DDP). The results demonstrate that the mixture of PPy‐Fe2O3 and DDP exhibits a surprising synergistic effect on strengthening the comprehensive properties of EP composites. Specifically, EP composite containing 0.2 wt% PPy‐Fe2O3 and 9.8 wt% DDP achieves the UL94 V‐0 rating with a limiting oxygen index (LOI) value of 35.5%, while 10 wt% DDP only imparts a UL94 V‐1 rating and a LOI value of 34.0% to EP. Furthermore, 0.2 wt% PPy‐Fe2O3 shows a 11.0% reduction in peak smoke production rate and a 12.3% reduction in peak heat release rate of the EP/DDP system. The enhanced fire security of EP/DDP/PPy‐Fe2O3 is attributed to the formation of more phosphorus‐rich structures retained in the char, thus reducing the release of harmful gases including NH3, CO, and CO2, and generating more incombustible gases including H2O to weaken burning intensity. Meanwhile, the satisfactory compatibility of PPy‐Fe2O3 with epoxy matrix imparts a superior mechanical strength to EP composites.

Study on the effect of novel intumescent flame retardant composed of β-cyclodextrin modified ammonium polyphosphate and THEIC on the flame retardancy of LDPE composites

Enhancing polymer flame retardancy is crucial for lowering combustion-related exothermic heat and flue gas production. β-cyclodextrin microencapsulated ammonium polyphosphate (β-CD@APP) were synthesis through in-situ polymerization and combined with 1, 3, 5-tris (2-hydroxyethyl) isocyanurate (THEIC) as a novel intumescent flame retardant (IFR) to enhance the flame retardancy of low density polyethylene (LDPE). The results showed that APP's hydrophobic characteristic increased, which enhanced its polymer dispersibility. Compared with LDPE, the LOI value of β-CD@APP/THEIC/LDPE (LDPE5) was enhanced from 17.5% to 28.7% and the composites could meet the UL-94 V-0 standard. Smoke volume and thermal decomposition rate were reduced. Furthermore, a stable char layer was found, which can be seen from the SEM of the char slag and the Raman results. According to the above results, the thermal decomposition and possible mechanism of flame retardants in LDPE composites during combustion were studied.

Synthesis and synergistic effect of cuprous(I) oxide nanoparticles and polyethyleneimine modified ammonium polyphosphate on enhancing the flame resistance of epoxy resin

Abstract In this study, cuprous(I) oxide nanoparticles (Cu2ONPs) and APP@PEI (polyethyleneimine-modified ammonium polyphosphate) materials were successfully synthesized and combined to create a flame-retardant system for the fabrication of epoxy (EP) resin with high flame resistance. The characteristic results revealed that the synthesized Cu2ONPs exhibited a particle shape with a size below 200 nm. The synthesized APP@PEI material possessed dimensions ranging from 10–20 micrometers, featuring a core–shell structure. The combination of Cu2ONPs and APP@PEI has proven to be an effective flame-retardant system, significantly enhancing the flame resistance of EP resin. The epoxy-based composite prepared with 2 wt% Cu2ONPs and 18 wt% APP@PEI demonstrated high flame resistance, achieving a V-0 rating (the highest rating according to the UL-94 method for evaluating the flame retardancy of materials) and a limiting oxygen index value of 36% (indicating the material’s self-extinguishing ability). This limiting oxygen index value was significantly higher than that of neat EP resin, which only reached 19%. The characteristic results of the flame-retardant epoxy-based composite demonstrated that both APP@PEI and Cu2ONPs were well dispersed in the EP resin and did not undergo structural transformation during the material preparation process. APP@PEI and Cu2ONPs enhanced the thermal degradation of EP-based composite materials at lower temperatures, exhibiting a faster degradation rate compared to EP resin. This augmentation facilitates the formation of a protective char layer on the surface of composite, thereby shielding it from direct flame exposure during combustion. Cu2ONPs played a role as oxidative catalysts, acting as Lewis acids. In addition to enhancing fire resistance, APP@PEI and Cu2ONPs have increased thermal conductivity, reduced impact strength, maintained tensile strength, and improved flexural strength of the composite material based on EP compared to neat EP resin.

Intumescent closed-cell porous molecular engineering towards high flame retardancy and ultra-low smoke release epoxy resin

Wide applications of high-flammable epoxy resin (EP) bring potential fire risks with huge heat and smoke hazards. Although effective strategies for flame retardancy and heat suppression have been developed, there are still few measures for reducing smoke release synchronously. Herein, 2-aminobenzimidazole modified ammonium polyphosphate intumescent flame-retardant co-curing agent (ABMZ-APP), possessing excellent char-forming performance, is designed and endows EP/ABMZ-APP thermosets with excellent flame retardancy, heat suppressing, and smoke suppressing performance. It is worth mentioning that the total smoke production (TSP), and maximum smoke density (DSmax) of EP with 20 wt% ABMZ-APP decrease by 73.2%, and 67.6%, respectively. Deep investigation illustrates EP/ABMZ-APP suppresses the smoke by obstructing soot-precursor transfer through the special porous char structure, rather than altering the chemical changes in nucleation and growth processes of mature soot. Meanwhile, the closed-cell porous char layers, acting as physical barriers, obstruct the heat/fuels transfer simultaneously which is beneficial for suppressing sustained burning.

Sustainable Flame Retardant Coatings Derived from Chinese Lacquer Blend with Synergistic Flame Retardant Silicon-Modified Ammonium Polyphosphate

The intumescent flame retardant has a high efficiency of carbonization, oxygen barrier, and thermal interruption effect, which is considered to be a promising green and environmentally friendly flame retardant. Herein, we demonstrated a new approach to improve the flame retardant performance of Chinese lacquer films by adding silicon modified ammonium polyphosphate (SAPP), leading to superior flame retardant. SAPP drastically raised the limiting oxygen index (LOI) from 20.1% to 30.6%, and at the same time, the impact resistance was increased from 7 cm to 20 cm without changing the hardness of the lacquer films. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy were used to investigate the chemical components and morphology of the residual char of Chinese lacquer and SAPP composite films. The thermal degradation process of films was detected and analyzed by thermogravimetry and microcalorimetry, and the possible flame retardant mechanism was discussed. This simple approach opens up a new way to design for improved flame retardancy of organic film polymers.

Preparation and properties of modified ammonium polyphosphate synergistic with tris(2-hydroxyethyl) isocynurate for flame-retardant LDPE

Abstract UF-SiAPP was prepared by modifying ammonium polyphosphate with the urea formaldehyde resin (UF), tetraethylorthosilicate (TEOS), and vinyltriethoxysilane (A-151). Moreover, a new intumescent flame retardant (IFR) used for low density polyethylene (LDPE) flame retardant was obtained by mixing UF-SiAPP with tris(2-hydroxyethyl) isocynurate (THEIC). The structure, morphology, and mechanical properties of flame retardants and LDPE composites were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, TG, and universal material testing machines. Furthermore, the flame-retardant properties of LDPE composites were comprehensively investigated by limiting oxygen index (LOI), UL-94, and cone calorimetry tests. The results show that UF-SiAPP exhibits excellent hydrophobic properties and good compatibility with LDPE after being modified by UF, TEOS, and A-151. And the flame-retardant properties of LDPE composites are significantly improved by adding IFR-containing UF-SiAPP. Especially, the LDPE composites attained the LOI value of 30.5% and reached the V-0 level after introducing 20.0 wt% UF-SiAPP and 10.0 wt% THEIC. And the tensile strength reached 13.55 MPa, which was 10.33% higher than that of LDPE/IFR with UF-APP and 13.21% higher than that of LDPE/IFR without THEIC in the same proportion. The smoke density tests demonstrate that the addition of UF-SiAPP not only effectively improves the residual carbon content and thermal stability of LDPE composites but also significantly reduces smoke emissions.

Enhanced Flame Retardancy of Styrene-Acrylic Emulsion Based Damping Composites Based on an APP/EG Flame-Retardant System.

Developing flame-retarded styrene-acrylic emulsion (SAE) based damping composites is a challenging task because of their very high flammability. A promising approach is the synergistic combination of expandable graphite (EG) and ammonium polyphosphate (APP). In this study, the surface modification of APP was modified by commercial titanate coupling agent ndz-201 through ball milling, and the SAE-based composite material was prepared with SAE and different ratios of modified ammonium polyphosphate (MAPP) and EG. The surface of MAPP was successfully chemically modified by NDZ-201 through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), Energy Dispersion Spectroscopy (EDS), and contact angle. The effects of different ratios of MAPP and EG on the dynamic and static mechanical properties and flame retardancy of composite materials were explored. The results showed that when MAPP:EG = 1:4, the limiting oxygen index (LOI) of the composite material was 52.5%, and the vertical burning test (UL-94) was at the V0 level. Its LOI increased by 141.9% compared to the composite materials without flame retardant. The optimized formulation of MAPP and EG in SAE-based damping composite materials showed a significant synergistic effect on the flame retardancy of the composite material.

Flame retardancy and anti-impact performance of polyurea composite coating reinforced by modified ammonium polyphosphate and two-dimensional nano-fillers

The protection performance of polyurea (PUA) coating is limited due to its intrinsic flammability. In order to develop a PUA composite coating with outstanding flame retardant and anti-impact performance simultaneously, in this paper the modified ammonium polyphosphate (MAPP) and two-dimensional (2D) nanofillers of graphene oxide (GO) and Mg-Al layered double hydroxides (LDH) were introduced into PUA matrix. Thermal stability and combustion behavior of PUA composites were studied by thermogravimetric analyzer and cone calorimeter. Results show that PUA composite sample with 17 wt% MAPP, 1.5 wt% GO and 1.5 wt% LDH exhibited remarkable flame-retardant and fire protective performance. The flame retardancy index increases to 1.7 from 1.0 with the time required to burn out and total heat release THR being dramatically decreased by 31.0 % and 33.4 %, respectively. The dynamic mechanical properties of PUA composites at the strain rate as high as 4500 s−1 were investigated. The dynamic mechanical behavior of the PUA composite shows strong strain rate effect. The introduction of the flame retardant does not substantially damage the energy dissipating capacity and anti-impact performance of the PUA matrix. Interfacial properties of PUA composites were studied by standard avulse and shear methods. The PUA composites with LDH and GO could form stronger bonding with the steel compared to neat PUA.

The synergistic flame-retardant behaviors of soybean oil phosphate-based polyols and modified ammonium polyphosphate in polyurethane foam

The synergistic flame-retardant behaviors of soybean oil phosphate-based polyols and modified ammonium polyphosphate in polyurethane foam

A novel modified nano-alumina composite sol for potential application in forest firefighting.

Herein, modified ammonium polyphosphate wrapped nano-alumina (mAPP@Als) was first synthesized and then dispersed in traditional fire extinguishing solution (FES) to fabricate a FES-mAPP@Als composite sol. It was found that the phosphorus-silica containing units were attached onto the nano-alumina surface, and the mAPP@Als particles showed excellent dispersion level in FES with a single-domain particle size distribution range. Due to the synergistic effects of the phosphorus-nitrogen and silica-alumina flame retardant components, FES-mAPP@Als (5% concentration) coated wood exhibited improved limiting oxygen index (33.2%) and carbonization ability, and depressed heat release (41.9%) and smoke production (10.7%), as compared to the pristine wood. In addition, the FES-mAPP@Als composite sol showed enhanced fire-extinguishing and anti-reignition capacities compared to the FES. This research offers a novel composite sol fire extinguishing agent for fighting forest fires.

Modified Ammonium Polyphosphate and Its Application in Polypropylene Resins

Herein, a simple and environment-friendly method of coupling agent treatment of APP (ammonium polyphosphate) is provided and an optimum process of modification via coupling agent is identified. The effects of coupling agent type, dosage, modification time, and modification temperature on the modification of ammonium polyphosphate (APP) were investigated using an orthogonal experimental design. The modified ammonium polyphosphate (KAPP) was characterized under optimal process conditions using Fourier Transform Infrared (FT-IR), X-ray Diffraction (XRD), Thermogravimetry (TG), and Scanning Electron Microscope (SEM) analysis. The treatment greatly improved the water solubility, dispersibility, and thermal stability of KAPP; and the application of KAPP in polypropylene (PP) was investigated. The flexural properties, thermal stability, and flame retardancy were studied using mechanical testing, thermogravimetric analysis, oxygen index, and UL-94 vertical combustion. The results show that the KAPP-added polypropylene composites have better bending properties when compared with the APP-added PP composites. SEM analysis suggests that the surface of KAPP became smoother and flat; dispersion was better, compatibility with the PP matrix was improved, and there were no prominent voids and gaps in the cross-section. A different degree of improvement in flame retardancy was also observed as per the LOI and vertical combustion results, wherein the PP composites prepared by adding 20% KAPP achieved the LOI of 27.6% and passed the UL-94 test with V-0 rating.

Preparation of modified ammonium polyphosphate blended aqueous boron phenolic resin and its application to insulating paper

Preparation of modified ammonium polyphosphate blended aqueous boron phenolic resin and its application to insulating paper

Pyrolysis mechanism and combustion behaviors of high impact polystyrene improved by modified ammonium polyphosphate and graphene

Pyrolysis mechanism and combustion behaviors of high impact polystyrene improved by modified ammonium polyphosphate and graphene

Construction phosphorus/nitrogen-containing flame-retardant and hydrophobic coating toward cotton fabric via layer-by-layer assembly

Excellent flame-retardant cotton fabric with desired hydrophobic is of particular interests for both academia and industry. Herein, an effective multilayer coating consisting of phosphorylated polyethyleneimine (P-PEI) and hydrophobic modified ammonium polyphosphate (MAPP) was successfully constructed on cotton fabric through a facile layer-by-layer (LbL) assembly, which imparted high fire retardancy and desirable hydrophobic to the cotton fabric. Coated cotton fabric was characterized by Fourier infrared spectrometer, scanning electronic microscopy coupled with its energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, conforming that a phosphorus- and nitrogen-containing multilayer coating was homogeneous and uniform increase on the surface of cotton fabric. The resultant cotton fabric achieved self-extinguishing in vertical burning tests and a desired hydrophobic with a water contact angle of 127.4° with only 4BL coating. Moreover, the coated cotton fabrics exhibited a slight delay of ignition accompanied by remarkably decrease of heat release and the fire growth rate index, suggesting the outstanding fire safety. The flame retardancy of coated cotton fabric was enhanced and even not ignited at the heat flux of 25 kW/m2, but the hydrophobic was almost not changed with the increase of bilayer number. Additionally, the relevant analysis of residues and volatile gases manifested that the multilayer coating contributed flame-retardant activities in both condensed- and gas-phase via forming thermally stable char residues and inhibiting the release of flammable gases. Taking advantage of the features, this high efficiency coating together with the facile finishing technique would have great potentials in application of multifunctional cotton fabrics.

POSS‐modified ammonium polyphosphate for improving flame retardant of epoxy resins

AbstractAn innovative phosphorus‐silicone flame retardant (KAPP‐OGPOSS) was prepared by grafting octa (propyl glycidyl ether) polyhedral oligomeric silsesquioxane (OGPOSS) on ammonium polyphosphate (APP) through silane coupling agent (KH‐550). The chemical structure, morphology, flame retardancy, and mechanism of the obtained materials were comprehensively investigated. TG results demonstrated that EP with 15 wt% KAPP‐OGPOSS produced a char residue of 42.6% at 700°C, which is three times that of pure EP. The flame retardant tests showed that the limiting oxygen index value of EP/15 wt% KAPP‐OGPOSS was 30.6% (67.7% higher than that of neat EP) and its UL‐94 grade reached to V‐0 rating. Cone calorimeter testing indicated that the incorporation of 15 wt% KAPP‐OGPOSS to EP significantly reduced heat, smoke, CO, and CO2 release by 79%, 83%, 80%, and 82.5%, respectively. The modification of APP with OGPOSS was also beneficial for the improvement of the char yield and density of char. A flame retardant mechanism was revealed according to the investigation into the char residue. This modified approach provided an innovative yet practical means of enhancing the flame retardant properties of EP.

Bio-based arginine surface-modified ammonium polyphosphate: an efficient intumescent flame retardant for epoxy resin.

In this work, ammonium polyphosphate (APP) was surface-modified by bio-based arginine (Arg) for the first time to enhance its flame retardance for fire-safety epoxy resin (EP). The structure of Arg modified APP (Arg-APP) was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), 1H nuclear magnetic resonance (1H-NMR), and scanning electron microscopy (SEM). The results illustrated that Arg was attached on the surface of APP through a cation exchange reaction. With Arg acting as the efficient carbon source, the char-forming ability of Arg-APP was significantly improved as illustrated by thermogravimetric analysis (TGA). The flame retardance of EP/APP and EP/Arg-APP composites was evaluated using the limit oxygen index (LOI), vertical burning tests (UL-94), and cone calorimeter tests (CCT). The results showed that at the same weight loading (15 wt%), Arg-APP had better flame retardance and smoke suppression performance compared with pristine APP, which can be attributed to Arg-APP constituting an integrated intumescent flame retardant (IFR) and facilitating formation of char residues with significantly expanded structures and higher carbonization degrees. When the weight loading of Arg-APP reached 25 wt%, the EP/Arg-APP composite could achieve an LOI value as high as 34.7%, pass V-0 requirements in UL-94 tests, and decrease the peak heat release rate and total smoke production by 83.5% and 61.1% compared with neat EP in CCT, respectively, indicating the superior flame retardance performance of Arg-APP. Finally, the effects of the flame retardant additives on the mechanical properties of EP were evaluated by the differential scanning calorimetry (DSC) tests and tensile-strain tests. At the same additive weight loading (15 wt%), the EP/Arg-APP composite showed higher glass-transition temperature and better tensile-strain properties compared with EP/APP composite, which can be attributed to the Arg shell structure improving the compatibility between APP and the organic substrate. In conclusion, this work presents a convenient and environmentally friendly method to improve the practical performance of APP.

Chemically inorganic modified ammonium polyphosphate as eco-friendly flame retardant and its high fire safety for epoxy resin

The flame retardant of epoxy resin (EP) with simultaneously eco-friendly environment and high efficiency had gained much attention. Here, a tactful route was utilized to chemically modify ammonium polyphosphate (Fe@APP) through ion exchange reaction between APP and Iron (III) nitrate hexahydrate. Adequate characterizations confirmed the successful preparation of Fe@APP, then the cone calorimeter results displayed that the heat and smoke release of 5 wt% Fe@APP/EP composite had been largely decreased. In addition, the flame-retardant mechanism investigation illustrated that iron (III) not only obviously efficiently catalyzed the charring process of EP, but also promoted the early formation of P–O–C group in Fe@APP/EP composite via catalysis during combustion, which could reinforce the intumescent char structure and fire safety for EP.

Fabrication of Diaminodiphenylmethane Modified Ammonium Polyphosphate to Remarkably Reduce the Fire Hazard of Epoxy Resins.

A novel diaminodiphenylmethane (DDM) modified ammonium polyphosphate (APP) flame retardant, DDP, was successfully synthesized via ion-exchange reaction. DDP was introduced into epoxy resins (EPs) to reduce flammability. A comparable level of DDP exerts better flame-retardant and smoke suppression efficiencies in EP than APP. An EP blend containing 15 wt% DDP displays a limiting oxygen index (LOI) value of 37.1% and a UL 94 V-0 rating, and further exhibits a 32.3% reduction in total heat release and a 48.0% reduction in total smoke production compared with pure EP. The presence of DDP greatly facilitates char formation during combustion, and the char mass from thermal decomposition of an EP blend is 37.8% smaller than that of an EP blend containing 15 wt% DDP at 800 °C. The incorporation of DDP into EP blends has a smaller impact on the glass transition temperature and tensile strength than those of a comparable level of APP. This reflects the better compatibility of DDP with the EP matrix compared with that for APP.