Ammonium Polyphosphate Research Articles

Direct ink writing 3D printed graphene oxide nanocomposite aerogel for intelligent fire-warning and exceptional fire-shielding

Fabricating intelligent fire-warning sensors with controllable 3D structures and shapes by advanced manufacturing technology is a formidable challenge but remains the critical factor in broadening fire prevention and protection. Herein, the novel fire-warning aerogel with a high-fidelity 3D porous structure and diversiform geometrical features based on graphene oxide (GO), cellulose nanofiber (CNF) and ammonium polyphosphate (APP) was fabricated via direct ink writing (DIW) 3D printing combined with freeze-drying technology. Benefiting from the hydrogen bonding multi-interactions between the molecules as well as the ideal rheological properties, the ink containing 20 wt% of CNF (GA-CNF-20) had a dynamic yield stress of 620 Pa. As a result, the corresponding aerogel had a significantly improved elasticity modulus of 153 kPa and a compressive stress of 400 kPa at a deformation of 39.7 %. Meanwhile, GA-CNF-20 displayed an ultrafast fire-warning trigger time (1.32 s) and a long-term response time (170 s) because of the thermal reduction property of GO together with the in-situ phosphorus doping reaction of APP under fire. Besides, the GA-CNF-20 also exhibited a strong heat-insulating capability, high char-forming property, self-extinguishing performance as well as structure integrity in the burning test. The relevant improvement mechanisms were attributed to the non-flammable gas diluting effect, intumescent char layer barrier effect and fire blowing-out effect in both gas and condensed phases. Such self-supporting printed aerogel can potentially be used as a fire-warning sensor for designated systems with specific precision structure in multi-domains of electrical and traffic engineering.

Preparation of biobased guar gum polyelectrolyte complex coatings by sol‐gel method for improving the flame retardancy of ramie fabrics

AbstractIn this study, to improve the flame‐retardant properties of ramie fabrics (RFs), a polyelectrolyte complex (PEC) was prepared in a one‐step process using biobased guar gum (GG), polyethyleneimine (PEI), and ammonium polyphosphate (APP) and deposited on the surface of the RF to construct an intumescent flame‐retardant coating. Fabrics treated with PEC coatings exhibited excellent flame‐retardant properties. Specifically, the cone calorimeter test results revealed that an increase in sample weight of only 13.23 wt% resulted in significant reductions in the peak heat release rate (pHRR), total heat release (THR), and fire growth rate (FGR) of 91.37%, 65.12%, and 95.28%, respectively. Additionally, the limiting oxygen index (LOI) increased from 19.4% to 33.5%, and the fabrics self‐extinguished immediately after the ignition source was removed during the UL‐94 test. Scanning electron microscopy (SEM) of the char residue revealed expansion bubbles on the surface, suggesting that the PEC coating provides flame retardancy through a synergistic effect involving both the gas phase and the condensed phase. This study provides a simple and convenient solution for realizing green and efficient flame‐retardant coatings on RF.

Enhanced flame retardancy and thermal insulation of epoxy resins composites incorporated with ammonium polyphosphate and ionic liquids loaded CuO-ZnO hollow spheres

Epoxy resin, as a thermosetting polymer material with good performance, has been limited in application due to its high flammability. In this investigation, porous CuO-ZnO hollow spheres (CZHS) were prepared by a hydrothermal method. By incorporation with ionic liquids loaded CuO-ZnO hollow spheres (CZHS@Ils) and ammonium polyphosphate (APP) into epoxy resin (EP) matrix, a new composite flame retardant material, named as EP/7.5APP/1.5CZHS@ILs, was developed for improvement of their thermal insulation and flame retardancy. The thermal conductivity of EP/7.5APP/1.5CZHS@ILs was measured to be 0.0197 W m −1 K −1, which is lesser than that of APP incorporated epoxy resin (EP/APP), demonstrating good thermal insulation capability. The flame retardancy were assessed using the limiting oxygen index (LOI) test, the Vertical flame testing (UL-94) test, and the cone calorimeter (CC) test. The results obtained from LOI test show that the EP/7.5APP/1.5CZHS@ILs has good flame retardancy with a LOI value of up to 28, better than that of pure EP which has a LOI value of 19.2. Moreover, a V-0 level of the EP/7.5APP/1.5CZHS@ILs was observed from the UL-94 test. The peak heat release rate (PHRR) was reduced to 257.9 kW m−2, which is 74.8 % lower than that of the pure EP. Such results are attributed to the synergy effect of CZHS@ILs and APP which offers the epoxy resin excellent flame retardancy. Taking advantages of the excellent thermal insulation, flame retardancy and better mechanical properties, the as-resulted EP/7.5APP/1.5CZHS@ILs may hold great potential for future thermal insulation and flame-retardant applications of energy saving building.

The preparation of ammonium polyphosphate@ nickel/cobalt-layered double hydroxide and its application as flame retardant in thermoplastic polyurethane

Inspired by the significant synergistic effect of transition metals and ammonium polyphosphate (APP) on flame reatrdancy, a nickel/cobalt-layered double hydroxide derived from a selected zeolitic imidazolate framework-67 (APP@NiCo) was constructed onto the surface of APP to enhance the fire safety of thermoplastic polyurethane (TPU). The results demonstrated that TPU containing 6 wt% APP@NiCo exhibited a LOI value of 27.7 % and achieved UL-94 V-0 rating. Furthermore, there was a significant reduction in the peak heat release rate, heat release rate, and total smoke production by 72.8 %, 37.5 % and 56.9 %, respectively. The remarkable improvement in flame retardancy was contributed to the highly synergistic charring catalysis of APP and dual transition metals cobalt and nickel, which effectively promoted the formation of robust char layers during TPU combustion for enhancing fire safety.

Effect of silane coupling agent on mechanical properties, flame retardancy, and ceramifiable behavior of ceramifiable flame‐retardant silicone rubber composite

AbstractIn order to improve the dispersibility of inorganic fillers and enhance its ceramifiable flame‐retardant efficiency, the ceramifiable flame‐retardant silicone rubber composites were prepared using glass powder, zinc borate, ammonium polyphosphate, mica powder, platinum catalyst as ceramifiable flame‐retardant agent, and various silane coupling agents as interfacial modifier. The micromorphology, mechanical properties, flame retardancy, thermal stability, and combustion behavior of ceramifiable flame‐retardant silicone rubber composites, as well as the flexural strength of the corresponding ceramics generated after pyrolysis of the composites were examined. The results reveal that the inclusion of silane coupling agents improves the dispersibility of ceramifiable flame‐retardant agents substantially. The mechanical properties, flame retardancy, thermal stability, and combustion behavior of ceramifiable flame‐retardant silicone rubber composites are all improved. When compared to a composite without a silane coupling agent, the tensile strength of the composite can be improved by up to 1.9 times. Only 0.5phr silane coupling agent is required to raise the vertical combustion rating from V‐1 to V‐0, and the composite with 3 phr KH570 has a LOI value of 38.6. Meanwhile, the heat release rate of the composite is reduced to a certain extent, and the time to ignition and residue are dramatically enhanced after the addition of silane coupling agent in the cone calorimetry test. Moreover, flexural strength of the corresponding ceramics generated after pyrolysis of the composites rapidly increases with increasing silane coupling agent content, which can reach to 24.7 MPa with addition of 3 phr KH570.

Investigation of the Effects of Phosphate-Containing Flame-Retardant Chemicals on Particleboards Produced Using Urea-Formaldehyde Resin.

In this study, urea-formaldehyde resins containing different phosphate-based flame retardants (FRs) were prepared to produce wood-based panels (medium-density fiberboard, particleboard, and veneer board), and their flammability properties were investigated. The changes in the gelation times were investigated when the phosphate-containing FRs used in different amounts were mixed with the resin. Chemicals that have both hardener and flame-retardant properties at the same time have been studied. In addition, the pH and thermal analyses of the resin and flame-retardant mixtures prepared in this study were performed by a pH meter and thermogravimetric analysis, respectively. The limiting oxygen index, UL-94 vertical burning, and cone calorimetry tests on the samples with the best combustion characteristics were carried out by sizing the particleboards in accordance with the standards and applying the prepared flame-retardant resins on them. The distribution of flame-retardant resin on the particleboard surface was investigated for the samples prepared by scanning electron microscopy. As a result of the analyses, it was determined that the samples containing 20% ammonium polyphosphate had good nonflammability properties.

Effects of phosphorus fertilizer type and dripline depth on root and soil nutrient distribution, nutrient uptake, and maize yield under subsurface drip fertigation

ContextSubsurface drip irrigation can potentially increase nutrient uptake by altering the spatial distribution of nutrients and roots, but the efficiency enhancement potential of different phosphorus (P) sources combined with varying dripline depths still requires further evaluation. MethodsWe established a 2-year field experiment with spring maize in 2021 and 2022 to determine the regulatory effects of three P sources [P1, monoammonium phosphate (MAP); P2, ammonium polyphosphate (APP); and P0, no P] and three dripline depths (D0, surface drip irrigation, 0 cm; D15, subsurface at 15 cm depth; and D30, subsurface at 30 cm depth) on the soil NO3-N, NH4-N and Olsen-P distribution, root distribution, nitrogen (N) fertilizer partial factor productivity (PFPN) and P use efficiency (PUE), and grain yield. ResultsWe found a significant coupling effect between the P source and dripline depth, both of which significantly impacted soil nutrients and root distribution, grain yield, PFPN, and PUE. In P1D15 and P2D15, the highest soil NO3-N and Olsen-P contents were observed at soil depths of 0–30 and 10–20 cm and at 0–30 and 10–30 cm, respectively. Similarly, in P1D30 and P2D30, which were 20–40 and 20–40 cm, and 20–40 and 30–60 cm, respectively. Compared to the other treatments, P2D15 and P1D30 exhibited considerable increases in root length density at the 30–60 cm soil depth of 37∼52 % and 28∼58 %, respectively. Regardless of the dripline depth, P0 resulted in the lowest yield during both growing seasons. P1D30 and P2D15 were found to be the optimal combinations for achieving higher grain yield, PFPN, and PUE, as they were able to achieve a high degree of coordination between soil available N and Olsen-P, as well as root distribution. ConclusionsThe recommended approach for optimizing nutrient and root spatial distributions under subsurface drip irrigation systems involves the use of poly-P fertilizer (APP) in conjunction with shallow dripline depth and ortho-P fertilizer (MAP) paired with deep dripline depth, which provides valuable guidance for co-fertigation practices involving N and P fertilizers.

Effect of ammonium polyphosphate on flame retardancy of bio-based rigid polyurethane foams

Rigid polyurethane foam (RPUF) has attracted a lot of attention as a multifunctional material. However, the use of fossil fuels in various fields is limited due to their flammability and excessive consumption in the preparation process. In order to solve this problem, a sustainable bio-based RPUF was prepared by ammonium polyphosphate (APP) and lignin-based polyol flame-retardant modification. The impact of APP on the smoke characteristics, flame retardancy, and thermal behavior of lignin-based polyol RPUFs was examined. The modified RPUF (RPUF-20) with 20 wt.% APP had the greatest starting temperature and residual rate. The maximum activation energy (E) and best thermal stability were found in the pyrolysis kinetics calculation utilizing the thermogravimetric trajectory compared with other specimens. Cone showed that when RPUF-20 was compared with RPUF-0, the peak heat release rate was lowered by 79.43%, 72.79%, and 67.91%, and the total heat release was reduced by 50.59%, 56.29%, and 37.14%, respectively. In addition, RPUF-20 had the lowest smoke density, according to the statistics. The current results showed that RPUF-20 had low smoke toxicity and outstanding flame retardancy, which gave rise to a novel notion for RPUFs following flame-retardant modification using biomass.

Synthesis of MgAl-LDH from three alkali sources for boosting flame retardancy of EP with APP

Epoxy resin (EP) is used in construction materials due to its low curing shrinkage, excellent chemical stability, and mechanical properties. However, its flammability limits applications in the field of construction. Co-precipitation method with sodium hydroxide as the alkali source and hydrothermal method with urea as the alkali source are the common ways to prepare MgAl-LDH. In this study, MgAl-LDH1 (abbreviated as LDH1) was prepared by using NaOH as the alkali source at 65 ℃ for 12 h, MgAl-LDH2 (abbreviated as LDH2) by using urea as the alkali source at 120 ℃ for 12 h, and MgAl-LDH3 (abbreviated as LDH3) was prepared by using triethanolamine as the alkali source at 100 ℃ for 2 h. Then, LDH1, LDH2, LDH3 were compounded with ammonium polyphosphate (APP) to synergistically enhance the flame retardant properties of EP (Composite material abbreviated as LDH1-APP-EP, LDH2-APP-EP, LDH3-APP-EP). The results showed that the best flame retardant effect was achieved after compounding APP (5 wt%) with LDH3 (5 wt%) prepared with triethanolamine as the alkali source. Compared with Pure-EP, the peak exothermic rate and peak smoke production rate of LDH3-APP-EP prepared with triethanolamine as the alkali source decreased by 74.54 % and 67.44 %, respectively. Compared with LDH prepared with NaOH and urea as the alkali source, LDH prepared with triethanolamine as the alkali source has a larger layer spacing and a higher weight loss percentage which releases more gases, moisture, and carbon layers formed by triethanolamine during the combustion process to reduce the heat release from the fire. It’s evident that LDH3-APP-EP prepared with triethanolamine as the alkali source has higher residual carbon densities and the lowest residual carbon values based on SEM and Raman test results. This result proves that the LDH3 with triethanolamine as the alkali source has a good effect on EP flame retardation in this paper which provided a new way to design new efficient flame retardants.

Encapsulating montmorillonite and ammonium polyphosphate in one polyurea microcapsule to improve flame‐retardant and mechanical properties of polypropylene composites

AbstractAmmonium polyphosphate (APP) and montmorillonite (MMT) have been widely used in the flame‐retardant of polypropylene (PP), but the low synergistic flame‐retardant efficiency and their poor compatibility with PP matrix need to be greatly improved. In this work, APP and MMT were encapsulated in the one microcapsule (PU@A‐M) at the determined optimal ratio through the “bridging” reactions of diethylenetriamine (DETA) with APP and MMT. Compared with the PP/A + M composites with the physical mixture of APP and MMT, the limiting oxygen index, peak of heat release rate, total heat release, and total smoke production of PP/PU@A‐M were decreased by 5.7%, 48.8%, 3.1%, and 20%, respectively. The well‐dispersed PU@A‐M with charring‐forming agent (CFA) generated continuous and compact char layers with COP, COSi, and SiOP crosslinking structure. Furthermore, the tensile strength and elongation at break of PP/PU@A‐M were enhanced by 4.8% and 36.9%, respectively, as compared with PP/A + M because of good dispersibility and compatibility of PU@A‐M in PP matrix.

Enhancing Flame-Retardant Properties of Polyurethane Composites Using N-β-(Aminoethyl)-γ-aminopropyl Trimethoxysilane and Carbon Black Co-Modified Ammonium Polyphosphate

The search for a straightforward method to obtain efficient, affordable, and long-lasting flame retardants with both desirable flame-retardant and mechanical properties for polyurethane (PU) composites remains a significant challenge. In this study, the surface of ammonium polyphosphate (APP) was modified using N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane (KH792) via an ion-exchange reaction, and the modified APP was coated with nanoscale carbon black (CB) to obtain CBAPP. CBAPP demonstrated good compatibility within the PU matrix and notably increased the tensile strength of the PU composites. Furthermore, CBAPP significantly enhanced the flame-retardant properties of the PU composites. The CBAPP/PU composite with a CBAPP mass fraction of 20% achieved a limiting oxygen index of 41.5% and a UL-94 class of V-0. According to the results of this study, our modification approach can be applied to develop other high-performance flame-retardant polymer-based composites, representing a significant contribution to the field of fire safety materials.

Effects of novel halogen-free flame-retardant binary additives on thermal stability, degradation kinetics and flame retardancy of cotton cellulose biomacromolecule

The principal component of cotton fibers is the cellulose biological macromolecule. However, its highly flammable nature has significantly constrained its utilization in fields where flame retardancy is essential. Herein, in this work, a highly effective binary composite flame retardant coating (APP/MEL-SWCNHs) with ammonium polyphosphate and modified single-walled carbon nanohorns (MEL-SWCNHs) was chemically attached to cotton fabric. With the add-on of 11.3 %, the treated cotton fabric (APP/MEL-SWCNHs)4 exhibited remarkable flame-retardant and self-extinguishing properties. Its LOI value increased to 23.7 ± 0.1 %, and the damage length was significantly reduced from 30.0 ± 0.1 % cm to 7.9 ± 0.1 % cm compared to the pristine cotton fabric. Despite partial carbonization, (APP/MEL-SWCNHs)4 preserved its original structure. Importantly, in the cone calorimeter test, both the pHRR and THR of (APP/MEL-SWCNHs)4 were drastically decreased by 71.8 % and 35.8 %, respectively. The APP/MEL-SWCNHs coating functioned as a flame retardant by inhibiting the emission of flammable volatiles, releasing non-flammable gases, and encouraging the formation of char layer during combustion. Significantly, thermal degradation kinetic analysis revealed that the third-order kinetic equation (O3) was found to have the strongest correlation with (APP/MEL-SWCNHs)4 in both air and N2 atmospheres. The higher activation energy (E) for (APP/MEL-SWCNHs)4 confirmed that incorporating MEL-SWCNHs improved the thermal stability of the char layer.

Construction of highly efficient flame retardant cellulose nanofibrils/bamboo activated charcoal based composite aerogel sheet for excellent PM2.5 removal

Developing biomass air filter materials with efficient filtration for particulate matter 2.5 (PM2.5) and low pressure drop is a great challenge. Targeting this issue, cellulose nanofibrils (CNF) were employed as the skeleton materials mixing with bamboo activated charcoal (BAC), polyethyleneimine (PEI), and ammonium polyphosphate (APP) as the functional fillers, followed by freeze-drying and hydrophobic modification to prepare CNF/BAC based composite aerogel sheet for capture for PM2.5. The resulting aerogel sheet showed good filtration efficiency for PM2.5 (98.64 %), which benefited from the three-dimensional network structure from CNFs and PEI and electrostatic adsorption of both BAC and APP with negative charge. After reusing for 5 times, the filtration efficiency of the system could still maintain at 95.88 %. In addition, the introduced both APP and PEI made the system have excellent flame retardant through the synergistic effect of nitrogen and phosphorus. In view of excellent properties and simple preparation, this work supplies a promising way to prepare multifunctional biomass air filter.

Study on Synergistic Flame-Retardancy of Surface Modified Zinc Stannate and Ammonium Polyphosphate on Polypropylene Nanocomposites

The effect of zinc stannate and synergy between zinc stannate with ammonium polyphosphate in polypropylene matrix is studied. The zinc stannate nanoparticles were synthesized by surfactant assisted low temperature precipitation method, and further surface modified with tetraethyl-orthosilicate at room temperature. Zinc stannate (ZS) and ammonium polyphosphate (APP) were incorporated in polypropylene matrix (1, 5 and 10 % by wt.). PP nanocomposites were analysed for flexural strength, tensile strength, linear burning rate, smoke density and LOI test. Morphology of nano particles and composites were analysed by FESEM. Mechanical analysis of PP nanocomposites demonstrates that, the modified ZS-TEOS performed better than unmodified ZS. Smoke density profiles suggest that the APP could slightly generate more smoke in PP with ZS and ZS-TEOS. Linear burning rate test results indicates that the APP with ZS and ZS-TEOS provide stability to PP for resisting flame spread.

Study of the morphology, structure, and properties of ammonium polyphosphate materials encapsulated by urea-melamine-formaldehyde resin, and the potential for manufacturing fire-resistant polypropylene composites

Study of the morphology, structure, and properties of ammonium polyphosphate materials encapsulated by urea-melamine-formaldehyde resin, and the potential for manufacturing fire-resistant polypropylene composites

Kinetic Properties of Combustion and Pyrolysis of Masson Pine with Synergistic Flame Retardancy by GUP-APP-silica Sol

ABSTRACT In order to investigate the effect of guanylurea phosphate-ammonium polyphosphate-silica sol on the combustion and pyrolysis characteristics of Masson Pine, UL-94 horizontal and vertical burner, LOI tester, cone calorimeter, and thermogravimetric analysis were used to study the flame retardant wood, and Coats-Redfern model was used to analyze its pyrolysis kinetics. The results showed that the combined use of guanylurea phosphate-ammonium polyphosphate-silica sol had a significant synergic flame retardant effect on Masson pine. When the mass ratio of guanylurea phosphate, ammonium polyphosphate, and silica sol was 2:1:1, the heat release rate and total heat release of flame retardant pine were decreased by 54.7% and 44.7% compared with pure Masson pine, and the LOI was increased by 77.8% compared with the control group. In addition, the addition of silica sol in the flame retardant reduces the effect of flame retardant on the mechanical properties of wood. Raman analysis of carbon layer showed that the R-value of char residue decreased by 5% and 13% when the mass fraction ratio of guanylurea phosphate, ammonium polyphosphate, and silica sol was 5:1:2 and 2:1:1, respectively, indicating that the compound flame retardant effectively promoted the conversion of amorphous carbon into graphite structure. The TG results of the 5:1:2 and 2:1:1 ratios of guanylurea phosphate, ammonium polyphosphate, and silica sol groups showed that the pyrolysis temperature of flame-retardant pine advanced by about 100°C at the heating rate of 15 ℃/min, and the final char residue rate and apparent activation energy were 15.22%, 18.61%, 24.35 kJ/mol, and 23.76 kJ/mol, respectively. These results indicated that the synergistic flame retardant system of guanylurea phosphate-ammonium polyphosphate-silica sol reduced the apparent activation energy of pine pyrolysis, effectively inhibited the pyrolysis of Masson Pine, and enhanced the thermal stability, char forming ability, and flame retardant property.

The Effect of Expanded Vermiculite on the Fire Resistance of Waterborne Acrylic Coatings.

Due to their ability to prevent or slow the spread of fires, fire-retardant coatings are utilized as the main means of fire protection for steel structures, combining easy application and high economic efficiency. This study investigates the effects of the particle size and dosage of expanded vermiculite (EV) on the fire resistance and application performance of coatings. Ammonium polyphosphate, melamine, and pentaerythritol were used as intumescent fire-retardant systems, along with waterborne hydroxyl-modified acrylic resins as the film-forming substances. The properties of fire resistance coatings were tested via scanning electron microscope (SEM), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), limiting oxygen index (LOI), and cone calorimetry. The excellent fire performance of the coatings with 3 wt.% 300-mesh EV was proven, exhibiting a relative expansion of 30.43 times. Moreover, the surface structure of the charcoal layer was dense. The total smoke production (TSP) and smoke concentration (TSR) were only 0.18 m2 and 0.25 m2/m2.

Towards the Reuse of Fire Retarded Polyamide 12 for Laser Sintering.

The control of powder aging during Selective Laser Sintering (SLS) processing is one of the challenges to be overcome for the implementation of this technique in serial production. Aging phenomena, because of the elevated temperatures and long processing times, need to be considered when a fraction of the polymer powders present in the build chamber and not used to manufacture the parts are reused at various times. The aim of this study was to investigate the influence of successive reuse of blends of pure Polyamide 12 and its blends with two types of flame retardants (FR): ammonium polyphosphate (APP) and zinc borate (ZB). The composition of the blends was 70/30 (wt/wt) PA 12/FR. Four successive processing stages have been carried out by collecting the remaining powder blend each time. The powders were re-used using the same processing parameters after sieving. DSC measurements showed that the incorporation of FRs entailed a reduction in the processing window up to 4 °C; nevertheless, no further reduction was noted after aging. The TGA curves of aged blends of powders were also similar for pure PA 12 and PA 12 with FR. In addition, initial and reused powders presented a higher degree of crystallinity than the specimens processed from the powders. The heterogeneous character of the PA 12 after LS processing or reprocessing was shown through Pyrolysis Combustion Flow Calorimetry (PCFC) and cone calorimeter (CC) tests. FTIR analysis also showed that post-condensation reactions have occurred. The mode of action of the flame retardants was clearly seen on HRR curves at both tests. The first reuses of PA 12 powders entailed a significant reduction in time to ignition at the cone calorimeter (150 for the initial material to around 90 s for the reused material), indicating the formation of short polymer chains. Only in the case of zinc borate was it noticed that re-used powder was detrimental to the fire performance because of a strong increase in the value of pHRR (between 163 and 220 kW/m2 for reused material instead of 125 kW/m2 for the initial one).

Tailoring surface terminals of Ti3C2Tx MXene microgels via interlayer domain-confined polyphosphate ammonium for flexible supercapacitor applications

The MXene material shows potential for flexible energy storage devices due to its high pseudocapacitance and mechanical flexibility. However, MXene nanosheet self-stacking and –F terminal functional groups can hinder active site and ion dynamics, thus affecting the energy storage performance. Herein, we present an interlayer domain-confined strategy that involves the introduction and crosslinking of ammonium polyphosphate (APP) confined to the interlayer of Ti3C2Tx MXene sheets, which induces gelation of the MXene to form a 3D network structure and enlarge their interlayer spacing. And then the cross-linked APP is converted into nitrogen and phosphorus terminals on Ti3C2Tx MXene via thermal treatment. The nitrogen terminals in the form of the pyrrole nitrogen and pyridine nitrogen, and phosphorus terminals of P–O bonds enhance the activity of the redox reaction and the dynamics of the ions, resulting in the boosted energy storage capacity of MXene. The density functional theory (DFT) calculations reveal that nitrogen-phosphorus co-doping modulates the surface electronic states of MXene and contributes to the increase of the electrical conductivity of Ti3C2Tx MXene. As a supercapacitor electrode, Ti3C2Tx MXene with N/P terminals exhibits a higher specific capacitance of 597.8 F/g (1777F cm−3) than the raw Ti3C2Tx MXene (384 F/g). In addition, the quasi-solid state flexible symmetric supercapacitor assembled by Ti3C2Tx MXene with N/P terminals can achieve an energy density of 12.5 Wh kg−1 at a power density of 250 W kg−1. Therefore, this work provides a new strategy for terminal modification of MXene and high-performance MXene supercapacitors.

Synergistic Effects of Titanium-Based MOFs MIL-125 with Intumescent Flame Retardants in ABS Polymer Composites on Flame Retardancy Study

The intumescent flame retardant (IFR) technique is an alternative to halogen-based flame retardants for reducing fire hazards in polymers. However, IFR has drawbacks like unsatisfactory flame-retardant efficiency and high loading requirements. In this study, MIL-125 (Ti-based metal–organic framework) is added to ABS/IFR composites to improve flame retardancy and reduce smoke emissions. Thermogravimetric analysis (TGA) results indicate that combining ammonium polyphosphate (APP) and expandable graphite (EG) increases charred residue and slows mass loss compared with the original ABS resin. The ABS/IFR/MIL-125 system stabilizes the char layer, serving as a protective shield against combustible gases during combustion. Additionally, MIL-125 enhances performance in microscale combustion calorimetry (MCC) flammability testing. In fire tests (UL-94, limiting oxygen index (LOI), and cone calorimeter), the ABS/IFR/MIL-125 system achieves a UL-94 V0 rating and the highest LOI value of 31.5% ± 0.1%. Peak heat lease rate (PHRR) values in the cone calorimeter are reduced by 72% with 20 wt.% of additives, and smoke production decreases by 53% compared with neat ABS. These results demonstrate the efficient synergistic effects of MIL-125 and IFR additives in improving the formation and stability of the intumescent char layer, thereby protecting ABS from intense burning.