Impact of decabromodiphenyl ethane and ammonium polyphosphate on the coloration and thermal stability of polypropylene

Enhancement mechanism of ammonium polyphosphate on flotation separation of pyrite from fine serpentine

Development of flame-retardant bamboo particleboards using bio-based adhesives and ammonium polyphosphate

• APP application increased Olsen-P in calcareous soil, but decreased it in acid soil. • APP increased labile P i while decreased more stable P i in calcareous soil. • APP application reduced labile P i and elevated labile P o in acid soil. • Abiotic and biotic factors affected P availability in the calcareous and acid soil, respectively. • APP with more P species coexistence could increase soil P availability. The effects of ammonium polyphosphate (APP, (NH 4 ) n+2 P n O 3n+1 , n < 20) on soil phosphorus (P) availability vary depending on polymerization distributions and the soil type, yet the mechanisms driving these differences remain unclear. This study explored the availability and transformation of P affected by APP1 (P species of P 1 -P 2 ) and APP2 (P species of P 1 -P 7 ) in two different soils, in comparison with conventional ammonium phosphates (APs). APP application increased Olsen-P by 10.7–24.8% in calcareous soil, but decreased it by 2.6–10.8% in acid soil relative to APs. In calcareous soil, APP significantly increased soluble-P, adsorbed-P, and Fe-associated P, as reflected by CaCl 2 , NaHCO 3 , and NaOH extractable Ps, while decreased more stable Ca-associated P and occluded P indicated by NH 4 Ac and Na 3 C 6 H 5 O 7 -Na 2 S 2 O 4 -NaOH extractable Ps. The changes in the composition of CaCO 3 and Fe/Al oxides together with/without the reduced organic carbon loss mainly contributed to the decrease in P sorption/precipitation and the increase in P desorption/dissolution. In acid soil, APP significantly increased microbial biomass P, leading to reduced labile inorganic P and elevated labile organic P. Meanwhile, APP increased both oxalate-extractable and complex Fe/Al oxides, which affected P adsorption–desorption to a certain extent. Compared to APP1, APP2 resulted in P existing in a more labile adsorbed state, thereby increasing P availability in both calcareous and acid soils. The main processes affecting P availability in the calcareous soils were abiotic transformations, while biotic transformations played the key role in the acid soils.

Sustainable utilization of distiller’s dried grains with solubles: Ammonium polyphosphate bonded particleboard with enhanced strength and flame retardancy

ABSTRACT To address environmental concerns of conventional flame retardants, MgAl‐layered double hydroxide (LDH) was synthesized from hydro‐magnesite. Utilizing hydrotalcite's structural memory effect, Cu was incorporated into LDH through acid activation and reconstruction. The obtained LDH was combined with ammonium polyphosphate (APP) into polyvinyl chloride (PVC). Composite thermal stability and flame retardancy were systematically evaluated. Results demonstrated that MgAlCu‐LDH/APP/PVC exhibited optimal performance, with limiting oxygen index (LOI) increasing from 26.1% (pure PVC) to 31.4%, achieving UL‐94 V‐0 rating. Cone calorimetry tests showed 19.7% and 20.9% reductions in peak heat release rate (PHRR) and total heat release (THR), respectively. Peak smoke production rate (PSPR) and total smoke production (TSP) decreased by 27.8% and 48.9%. These enhancements originated from synergistic dilution of flammable gases by NH 3 (from APP decomposition) and CO 2 (from LDH). Additionally, APP's acidic sites and Cu's catalytic effect jointly promoted PVC dehydrochlorination and aromatization, forming a dense char layer that effectively suppressed heat and mass transfer. This acid activation–in situ replacement method provides a novel strategy for synthesizing MgAlCu‐LDH and other ternary LDHs, demonstrating promising potential for improving polymer fire safety.

ABSTRACT Epoxy resin (EP) is widely used in fields such as building materials, aerospace, and transportation; however, its high fire risk is considered the main factor limiting its practical use. To address this issue, ammonium polyphosphate (APP) is coated with phosphorus‐doped graphitic carbon nitride (PCN) to prepare PCN@APP. When compared with pure EP, the composite with high‐loading APP is observed to exhibit reduced mechanical properties. In contrast, the composite containing modified APP is shown to demonstrate enhanced mechanical performance. Specifically, the flexural strength and tensile strength are increased by 9.13% and 45.09%, respectively. With the incorporation of 20 wt% PCN@APP, significant reductions are achieved in key fire parameters: the peak heat release rate (PHRR), total heat release (THR), peak smoke production rate (PSPR), total smoke production (TSP), peak CO production (PCOP), and peak CO 2 production (PCO 2 P) are lowered by 66.6%, 66.2%, 71.8%, 78.7%, 65.5%, and 68.6%, respectively. TG‐IR results indicate that after adding the PCN@APP filler, the absorbance of CO and NO is reduced by 80.2% and 67.9%, respectively, demonstrating significant suppression of fire toxicity. This work is considered to provide valuable inspiration for the straightforward design of APP‐based flame retardants, thereby enhancing their flame‐retardant efficiency.

ABSTRACT The high flammability of ethylene‐vinyl acetate (EVA) copolymers limits their important applications in fire safety, thus it has become imperative to improve the fire retardancy through the incorporation of flame retardants. In this study, a novel two‐dimensional (2D) metal–organic frameworks (MOFs) material of ZIF‐L has been successfully synthesized and characterized. An intumescent flame retardant (IFR) composed of ammonium polyphosphate (APP) and tannic acid (TA) in conjunction with ZIF‐L was constructed and molten‐compounded into the EVA matrix. The flame retardancy of EVA composites was evaluated using limiting oxygen index (LOI) tests, vertical burning testing (UL‐94), and cone calorimetry tests. Compared with neat EVA, the EVA/29(APP/TA)/1ZIF‐L composite exhibited an increased LOI from 20.1% to 24.6%, an improved UL‐94 rating from none to V‐0, and a 60.5% reduction in peak heat release rate (pHRR). Analysis of the decomposition products and char residue suggests a synergistic flame‐retardant effect in condensed phase and gas phase. Moreover, owing to the UV absorption of TA and ZIF‐L and the free‐radical scavenging ability of TA, the EVA composites exhibited significantly enhanced UV shielding, reaching an “excellent” level.

ABSTRACT This article reports the preparation of a multi‐layer core‐shell flame retardant (APP@SiO 2 @MA) using melamine (MA), ethyl silicate (TEOS), and γ‐(2,3‐epoxypropoxy) propyltrimethoxysilane (KH‐560) as raw materials, coated with ammonium polyphosphate (APP). Apply the flame retardant to PPO/PS composite materials to improve their flame retardant properties and investigate its effect on the foaming performance of PPO/PS composite materials. This article confirms the successful microencapsulation of APP by SiO 2 and MA through energy dispersive spectroscopy (EDS) analysis, X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) observation. The combustion performance of P samples and their foam samples was evaluated through thermogravimetric analysis (TG), limit oxygen index (LOI), and UL‐94 vertical combustion test, the residual carbon quality significantly increased from 17% of PPO/PS to 38%, and the maximum oxygen index increased from 22.9% to 30.5%. At 165°C and 3.5 MPa foaming conditions, the foaming ratio increased from 1.18 to 4.56 times, and the maximum oxygen index after foaming was 27.9%. This study provides a green and convenient method for the preparation of flame‐retardant PPO/PS bead foam materials, expanding the practical application of PPO/PS in industry.

Lithium-sulfur (Li-S) batteries are regarded as a representative next-generation energy storage technology due to their high energy density, low cost, and environmental friendliness. Nevertheless, their widespread application is hindered by challenges such as the insulating nature of sulfur and Li2S, the larger volume expansion during cycling, and the serious side effects caused by the soluble lithium polysulfide (LiPSs), all of which collectively lead to severe capacity decay and poor cycling stability. Furthermore, the high flammability of sulfur is another critical safety concern, which has hindered its further application. To effectively address these limitations, this study designed and developed a flame-retardant sulfur cathode (CS@Al/APP) by encapsulating carbon-sulfur composites with aluminum hydroxide (Al(OH)3) and employing ammonium polyphosphate (APP) as a binder to enhance electrode stability and flame retardancy. Experimental results demonstrate that Al(OH)3 and APP synergistically improve the flame resistance by releasing inert gases and forming a protective char layer. Additionally, they enhance sulfur redox kinetics by efficiently trapping LiPSs. As a result, the CS@Al/APP cathode exhibits exceptional electrochemical stability, maintaining a reversible capacity of 1025.04 mAh g-1 after 100 cycles at 0.1C and delivering a discharge capacity of 744.2 mAh g-1 after 500 cycles at 1C. This study provides a feasible technical pathway for achieving lithium-sulfur batteries with high safety and high energy density.

Hydrophobic silica aerogels (SAs) have attracted much attention because of their excellent thermal insulation performance and have potential applications in energy conservation and emission reduction. However, the organic groups on its surface are flammable, which brings security risks and limits its application scope. In this study, two kinds of ammonium polyphosphate (APP) with different polymerization degrees, namely low-polymerization-degree APP (LAPP) and high-polymerization-degree APP (HAPP), were introduced into SA to prepare APP/SA composites, to improve the thermal safety of the materials. The results showed that APP with two polymerization degrees significantly delayed the initial decomposition and peak temperature of heat flow, and HAPP reduced the gross calorific value by 31.01% at most, which is 29.04% greater than that of LAPP, indicating that the effect of HAPP was slightly better than that of LAPP. With the increase in APP with two polymerization degrees, the density increased and the porosity decreased: LAPP system was 0.095-0.196 g/cm3 and 96.0-91.0%. Both made the thermal conductivity increase only slightly (up to 26.8 mW/m/K), but the sample still maintained excellent thermal insulation and hydrophobicity, which indicated that the addition of APP improved the thermal safety performance of SA while maintaining its basic excellent performance. This strategy provides an effective and simple way to improve the flame retardancy of SA, which makes SA more widely used in fields with strict requirements on thermal safety.

Ammonium polyphosphate modified epoxy–polyurethane system for high-performance bamboo composites with improved fire safety

ABSTRACT In this study, a hyperbranched macromolecular flame retardant (PTECK) containing nitrogen, phosphorus, and silicon was synthesized using cyanuric chloride (TCT), γ‐aminopropyltriethoxysilane (KH550), triethyl phosphate (TEP), and ethylenediamine (EDA) as starting materials. The chemical structure of PTECK was systematically characterized by Fourier‐transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and elemental analysis (EA). Subsequently, PTECK was combined with ammonium polyphosphate (APP) to prepare a flame‐retardant polypropylene (PP) composite via melt blending through hot pressing. Flame retardancy evaluations demonstrated that the incorporation of 6.67 wt% PTECK and 13.33 wt% APP into PP resulted in a limiting oxygen index (LOI) value of 30.3% and achieved a UL‐94V‐0 classification. Compared to neat PP, the peak heat release rate (PHRR) and total heat release (THR) of the PP/PTECK/APP composite were reduced by 78.2% and 68.3%, respectively, while the residual char yield reached 42.5%. Furthermore, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Raman spectroscopy (RS), X‐ray photoelectron spectroscopy (XPS), and infrared spectroscopy were employed to analyze the gaseous products and char residue, thereby elucidating the underlying flame retardancy mechanism.

Developing multifunctional materials that combine low thermal conductivity with high flame retardancy is key to meeting the demands of modern energy-efficient buildings. Chitosan (CS), with its natural biogenic properties and significant inherent flame retardancy, provides a unique design basis for high-performance thermal insulation and flame-retardant materials. In this work, we use an in situ coprecipitation strategy to load ammonium polyphosphate (APP) and magnesium phosphate compounds (main phase MgNH4PO4·6H2O) onto the three-dimensional framework of CS, successfully constructing a Mg and P codoped chitosan-based composite aerogel (recorded as CS@APP@Mg-P aerogel) that synergistically enhances thermal insulation and flame retardancy. This material exhibits thermal insulation properties, with a thermal conductivity as low as 0.0251 W m-1·K-1, primarily attributed to the three-dimensional network structure and high porosity of the chitosan matrix. Its flame-retardant performance meets the UL-94 V-0 standard, with a peak heat release rate (pHRR) as low as 17.30 kW m-2, significantly outperforming similar composite materials. Additionally, the aerogel exhibits high adsorption capacity for formaldehyde (average adsorption rate >80%). The comprehensive performance mentioned above is attributed to the synergistic interaction among the CS matrix, APP flame retardant, and magnesium phosphate reinforcing phase (MgNH4PO4·6H2O). This provides a strategy for developing biobased aerogels that integrate thermal insulation, flame retardancy, and formaldehyde adsorption, offering broad application prospects in energy-efficient buildings and indoor air purification.

Improving phosphorus (P)-use efficiency (PUE) while increasing crop yield is one of the greatest challenges in sustainable P management for sustainable agriculture. Types of P fertilizers and soil water supply impact P availability and crop growth, but how to optimize P fertilizer and water supply to enhance the foraging capacity of roots for P remains unclear. This study was aimed at characterizing the effects of different combinations of P fertilizers and water supply on maize growth, root properties and PUE in calcareous soil. A pot experiment with four P fertilizers [monoammonium phosphate (MAP), diammonium phosphate (DAP), ammonium polyphosphate (APP) and urea phosphate (UP)] was conducted under well-watered (watered) and water-deficit (dry) conditions using maize (Zea mays L.) in a greenhouse during the seedling stage. The interaction between P fertilizers and water supply significantly promoted the growth and P uptake of maize by modifying the root morphological and physiological traits. MAP and APP exhibited greater (by up to 62%) total root length in the watered than the dry treatments, resulting in a significant increase in the efficiency of root P acquisition. The APase activity in the rhizosphere soil of MAP and DAP declined (by 37%-62%) significantly, and the rhizosphere soil pH in the DAP treatment was 0.4 units lower in the watered than the dry treatments. APP improved the soil P availability more than the other P fertilizers (17%-41% higher in soil Olsen-P concentration) regardless of water supply. Optimal combination of P fertilizers and water supply promotes maize growth and PUE due to stimulating the root capacity to forage for nutrient and water resources by regulating the root morphological and physiological traits. Engineering root/rhizosphere by manipulating the interactions of P fertilizer types and water supply can improve nutrient use-efficiency and sustainable crop production.

Flame-retardant microcapsules were prepared using a urea–melamine–formaldehyde (UMF) shell and boric acid-crosslinked ammonium polyphosphate (APP) as the core to improve the dispersion stability and processing compatibility of phosphorus-based flame retardants. Thermal analysis showed that the microcapsules exhibited initial mass loss near 80 °C due to moisture evaporation and shell relaxation, while APP-related degradation occurred at higher temperatures, indicating delayed release of the core and enhanced thermal resistance through encapsulation. Scanning electron microscopy confirmed the formation of microcapsules, and morphological changes before and after combustion suggested the development of protective char layers. Boron-containing residues are expected to contribute to char stabilization through the formation of B–O–P structures during heating. The flame-retardant properties were evaluated using limiting oxygen index, smoke density, and vertical burning tests. Although the limiting oxygen index slightly decreased due to reduced accessible APP content, stable burning behavior was maintained, and characteristic char formation was observed after combustion. These results indicate that the UMF/APP microcapsules can improve thermal stability and handling of phosphorus-based flame retardants. The microencapsulation approach presented here may provide practical advantages for polymer processing and surface-coating applications.

ABSTRACT A fire‐retardant polyester‐based polyurethane adhesive was synthesized for laminating dual‐metallized PET films with both glass as well as aramid substrates. The resin, synthesized through chain extension of an MDI‐based prepolymer with butanediol and crosslinked using trimethylol propane (0.5 wt%), exhibited high thermal stability ( T onset &gt; 260°C) and flexibility ( T g = −37°C). The laminates prepared using the developed polyurethane adhesive met the adhesion and flexing requirements, however, they failed during vertical flammability tests. Incorporation of melamine‐coated ammonium polyphosphate (APP, 10% w/w) increased the char yield and enabled the laminates to pass key fire‐resistance tests, including heat resistance, thermal shrinkage, and flammability. The developed laminates demonstrated high flexibility and adhesion under dry/wet conditions and withstand 1000 flexing cycles even after immersion in hot water. Flexural rigidity was measured in both directions, and protection against radiative heat (84 kW/m 2 ) was quantified in terms of time to second degree burns (), yielding 21.5 s for aramid and 24 s for glass laminates. When assembled into a multilayer fire proximity suit configuration, both the laminates met the standard requirement (TPP = 35 cal/cm 2 ). The results demonstrate the viability of the adhesive system for fire proximity applications, with aramid substrates offering a practical alternative to glass fabrics.

Enhancing the flame retardancy of polymeric materials by adding only eco-friendly ammonium polyphosphate (APP) while simultaneously maintaining high-temperature resistance has become a challenge. Talcum has been introduced as a cooperative agent into the silicone rubber/APP system to investigate the effect of talcum on flame retardancy, thermal stability, and high-temperature resistance. The machining process induces the orientation of talcum in the system. The ceramifiable silicone rubber blends containing oriented talcum (e.g., sample SA6T4) exhibited superb flame retardancy, including an LOI of 29.4%, a UL-94 rating of V-0, and a peak heat release rate (PHRR) of 250.2 kW·m-2. More importantly, the blends present excellent thermal stability and high-temperature resistance, characterized by outstanding self-supporting properties and dimensional stability. Based on the structural analysis of the blends and their residues, the made of action for the improved flame retardancy may be attributed to the formation of a compact barrier layer. This layer is formed by oriented talcum platelets combined with phosphoric acid, from the thermal decomposition of APP, promoting crosslinking, thereby achieving a good inhibition barrier to inhibit heat feedback from the condensation zone. The excellent thermal stability and high-temperature resistance of the ceramifiable silicone rubber blends may be ascribed to a cooperative effect between APP and talcum at high temperatures, which facilitates the formation of ceramic structures. The novel ceramifiable silicone rubber composite has potential applications as flame-retardant sealing components for rail transit equipment and encapsulation materials for new energy battery modules.

ABSTRACT Developing polylactic acid (PLA) bioplastics that are both flame‐retardant and mechanically robust remains challenging, as most flame‐retardant approaches require high loadings or reduce toughness. Bio‐based modifiers rarely deliver flexibility, char formation, and effective flame inhibition at low levels, leaving a gap in achieving multifunctional PLA systems. Here, phosphorus‐modified castor oil (PMCO) was synthesized via solvent‐free transesterification of castor oil with trimethyl phosphate, yielding a bio‐based additive tailored for dual mechanical and flame‐retardant enhancement. PMCO, used alone or in combination with ammonium polyphosphate (APP), was incorporated into PLA via melt blending to evaluate synergistic effects. The phosphorus moieties in PMCO promoted char formation and gas‐phase radical quenching, while castor oil's long‐chain fatty acids imparted flexibility; APP reinforced condensed‐phase char development. Low PMCO loadings (1–3 wt%) enhanced tensile strength (up to 59.33 MPa) via plasticizing–reinforcing effects, whereas 5 wt% reduced stiffness; APP counteracted this in hybrid PLA/2.5%PMCO/2.5%APP, which restored tensile strength (58.15 MPa), doubled elongation at break (6.89%), and improved deformation resistance. Fire tests showed LOI rising from 19% (PLA) to 30% (hybrid), with UL‐94 reaching V‐0 and complete suppression of melt‐dripping. Cone calorimetry confirmed delayed ignition, lowered total heat release, and &gt; 40% smoke reduction. This dual‐modification strategy achieves balanced toughness and strong flame retardancy in bio‐based PLA at low additive levels. The design of PMCO enables efficient dispersion, reduced brittleness, and multifunctional performance, offering a pathway toward high‐performance PLA composites for packaging, electronics, and automotive applications.

Abstract Interest in liquid phosphorus (P) and potassium (K) fertilizers is increasing, often with claims of superior performance over dry‐granular sources. We compared yield and tissue‐nutrient responses of corn ( Zea mays L.) and soybean [ Glycine max (L.) Merr.] to dry versus liquid P and K. Field trials were conducted from 2021 to 2024 across 42 site‐years, including eight corn and six soybean sites, with separate P‐only, K‐only, and combined P+K trials for each crop. Each trial included a no‐fertilizer check and factorial combinations of source (dry vs. liquid) and rate (half vs. full). Triple superphosphate and muriate of potash were dry‐fertilizer sources, and ammonium polyphosphate and Nachurs K‐fuel were liquid‐fertilizer sources. Leaf nutrients were analyzed at V11–V12 (corn) and R2–R3 (soybean) stages, and yield was measured at maturity. In P‐ or K‐deficient soils, corn yield did not differ by sources; however, full‐rates increased yield by 5%–13% over half‐rates. For soybean, source and rate effects were not significant in single‐nutrient trials, whereas in P+K trials, full‐rates increased yield by 9%–10% over half‐rates. Across environments, yield responses aligned with tissue diagnostics; tissue‐K was consistently associated with yield gains, whereas tissue‐P was less predictive under common luxury P uptake. Overall, liquid sources provided no advantage over dry‐granular sources at equivalent rates. Half‐rate liquid did not match full‐rate dry yields, and co‐applied P+K mirrored single‐nutrient responses; yield differences reflected rate, not formulation or synergy. Results emphasize using soil‐test‐based rates, not formulation, when targeting yield, and tissue‐K as a more reliable in‐season indicator of crop response than tissue‐P.