Phosphorus-containing Flame Retardant Research Articles

Schiff base derivative flame-retardant endowing epoxy resin with toughness, transparency, and high flame retardancy

In this study, a novel phosphorus-containing flame retardant, SMAE, was prepared through a nucleophilic addition of N,N'-bis(salicylidene)ethylenediamine (SAED) and phenyl hypophosphite. SMAE can dissolve well in epoxy resin and provides molecular-level flame retardancy. By using SMAE as a co-curing agent and DDM to cure epoxy resin, EP/SMAE composites with excellent flame retardancy and good mechanical properties were obtained. As the dosage gradually increases, the limited oxygen index (LOI) values continue to rise. At a 5 % dosage, the Limiting Oxygen Index (LOI) value can reach 39.7 % and meet the UL 94 V-0 standard. It is observed that SMAE mainly exerts a blowing-out effect in EP. In addition, the use of SMAE as a co-curing agent can improve the impact strength of EP. The impact strength of 5 % SMAE/EP can reach 14.15 kJ/m2, which is 25 % higher than that of pure EP.

A new approach to prepare flame retardant epoxy resin with excellent transmittance, mechanical properties, and anti-aging performance by the incorporation of DOPO derivative

Aiming to develop high performance flame-retardant epoxy resin (EP), a novel phosphorus-containing flame retardant named 6-(3-(2-hydroxyphenyl)propyl)dibenzo-[1,2]oxaphosphinine 6-oxide (HP-DOPO) was synthesized and employed as a multi-functional additive for EP with simultaneously excellent flame retardancy, transmittance, mechanical enhancement and anti-aging. With 5 wt.% loading of HP-DOPO, EP composites showed outstanding flame retardancy with a high limiting oxygen index of 35.6 % and V-0 rating in UL-94 test, while the cone calorimetric test results demonstrated that HP-DOPO could efficiently restrain the heat and smoke release. Compared with pure EP, the resultant EP/5 %HP-DOPO exhibited superior mechanical properties with 27.9 % and 56.2 % increase in tensile and impact strengths, respectively. Furthermore, HP-DOPO accelerated the curing procedure and did not sacrifice the transparency of cured EP, while anti-aging performance was obtained at the same time. The exploration of this novel multi-functional additive provided a powerful basis for the technologies and potential industrial applications of epoxy materials.

Thermal decomposition kinetic study on one-pack formulations of epoxy resin cured with novel phosphorus-containing flame retardant latent curing agents

Several phosphorous-containing flame retardant latent curing agents newly derived from 4,4-diamino diphenyl sulfone (DDS) and 4,4-diamino diphenyl methane (DDM) were designed to cure epoxy resin alongside dicyandiamide (Dicy). The thermal decomposition and kinetics of cured one-packed systems were investigated in detail. The epoxy systems were studied under a nitrogen atmosphere by using thermal gravimetric analysis at different heating rates. The kinetics of thermal decomposition was evaluated by Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose, and Starink methods. The correlation coefficient for all systems obtained by the three above methods was almost equal to one, indicating that these three methods were correctly chosen. The results demonstrated that the activation energy of epoxy/Dicy blended with different phosphorous-containing DDS- and DDM-derived curing agents at a lower degree of conversion decreased by incorporation of the agents while increasing at a higher degree of conversion. The thermodynamic parameters (ΔH*, ΔG*, and ΔS*) of the studied systems were calculated by the obtained activation energy via three kinetics methods. It was found that as the conversion degree and the enthalpy increased, the Gibbs free energy decreased, while entropy changed from negative to positive values.

Synthesis phosphorus–sulfur reactive flame retardant for polyamide 66 with high flame retardant efficiency and low smoke

A sulfur- and phosphorus-containing flame retardant monomer phosphonic diamide, P-phenyl-N, N′-bis(p-sulfanilylphenyl) (PDDDS) was designed, synthesized, and incorporated into polyamide 66 (PA66) through polycondensation to suppress smoke generation upon combustion and achieve satisfactory mechanical properties, a good UL-94 rating (V-0), and a high limiting oxygen index (31.6%). The increased flame retardancy of the PA66-PDDDS copolymer was ascribed to its decomposition into (i) gas-phase P–O and SO2 species scavenging free radicals such as H• and OH• and (ii) condensed-phase products catalyzing the dehydration of PA66 to form char layer. Thus, our work presents a strategy for improving the fire safety of PA66 to significantly expand its practical application value.

A novel green phosphorus-containing flame retardant finishing on polysaccharide-modified polyamide 66 fabric for improving hydrophilicity and durability

Rising concerns about the toxic effects and environmental issues associated with various fireproof treatments on textiles have led to a demand for “green” materials. Chitosan (CS) is an amino polysaccharide green, recyclable, and non-toxic highly biocompatible biopolymer that consists of multiple hydroxyl groups and has a wide range of applications, including as a flame retardant additive. In this study, an eco-friendly bio-based formaldehyde-free flame retardant containing a higher level of phosphorus and nitrogen in phytic acid ammonia (PAA) was synthesized to amplify the most plentiful green chitosan (CS)-modified polyamide 66 (PA66) fabric surface through a simple pad-dry-cure technique for the improvement of durable flame retardancy with hydrophilicity. The findings revealed that each UV-grafted CS fabric could entirely stop the melt-dripping tendency during the vertical burning (UL-94) test and reached a V-1 rating. Meanwhile, limiting oxygen index (LOI) testing showed a rapid increase from 18.5 % to 24 % for the PA66 control and the PAA-treated (i.e., PA66-g-5CS-PAA) fabric samples, respectively. Moreover, compared to the PA66 control sample, a dramatic decrease in the peak heat release rate (PHRR), fire growth rate (FGR), and total heat release (THR) by approximately over 52 %, 0.63 %, and 19.7 %, respectively, was observed for the PA66-g-5CS-PAA fabric sample. Additionally, this arrangement of PAA catalyzed the charring of grafted CS and acted as a condensed phase flame retardant, resulting in a significant improvement in char yield% in both air and N2 atmospheres for the PA66-g-5CS-PAA fabric sample in TGA. In addition, only the lower grafting ratio of CS with PAA-treated fabric sample (i.e., PA66-g-2CS-PAA) could encourage it to gain its lowest water contact angle of 00, as well as impersonating a positive effect in improving the flame retardant coating durability in washing and sustaining even after 10 home laundering cycles. This phenomenon suggests that an actual hydrophilic and durable flame retardant finishing procedure for polyamide 66 fabrics might be applied with the novel, plentiful, sustainable, and environmentally friendly bio-based green PAA ingredient.

Facile modification of aluminum hypophosphate and its flame retardancy for polystyrene

A phosphorus-containing flame retardant, aluminum hypophosphite (AHPi), has been modified by (3-aminopropyl) triethoxysilane (KH550) to prepare flame-retardant polystyrene (PS). The influence of modified AHPi on the morphology and characterization was investigated, and differences in flame retardant properties of the PS/AHPi and PS/modified AHPi were compared. The PS composite can pass the vertical burning tests (UL-94 standard) with a V-0 rating when the mass content of modified AHPi reaches 20%, compared with the mass content of 25% AHPi. The element mapping of the PS composite shows that modified AHPi has better dispersion in PS than AHPi. Thermogravimetric analysis results indicated that adding modified AHPi can advance the initial decomposition temperature of the composite material. With the addition of modified AHPi, the decrease in peak heat release rate (pHRR) is more evident than AHPi, and the char yield of the resultant PS composites gradually increased. With the addition of 25% modified AHPi, the pHRR and total heat release of PS composites decreased by 81.4% and 37.6%. The modification of AHPi promoted its dispersion in the PS matrix and improved the char formation of PS composites. The results of real-time infrared spectrometry of PS composites, Fourier transform infrared spectra and X-ray photoelectron analysis of the char layer indicated that modified AHPi has flame retardancy in condensed and gas phases.

Enhancement of flame retardancy of solid polymer electrolyte based on phosphorus-containing ionic liquid polyurethane membrane for safe lithium batteries

The inherent defects such as flammable and inadequate cycle performance of polyurethane solid electrolytes impede their practical application in lithium batteries. Herein, phosphorus-containing flame retardant ionic liquid polyurethane (FR-ILPU) membrane is regard as an effective approach for overcoming the potential deficiencies. The FR-ILPU is fabricated by grafting phosphorus-containing diols and ionic liquids to polyurethane molecular segments. The FR-ILPU membrane exhibits benign flame retardancy, accompanying by the limiting oxygen index (LOI) value increases from 17.2% to 32.3%, while the total heat release (THR) and total smoke release (TSR) decrease 54.8% and 73.7%, respectively. Moreover, the SPE(15,5) electrolyte composed of FR-ILPU membrane, 15 wt% Li1.4Al0.4Ti1.6(PO4)3 (LATP) along with 5 wt% lithium bis-(trifluoromethanesulfonyl)imide) (LiTFSI) displays a wide electrochemical window of 4.84 V (vs. Li+/Li). In addition, an all-solid-state battery which assembled with lithium iron phosphate (LiFePO4), SPE(15,5), and Li anodes presents excellent cycling performance (157.3 mAhg−1, 0.2 C) and coulombic efficiency (99.1%) after 140 cycles at 70 °C, illustrating an enhancement of cycling performance than the cell assembled by R–PU(15,5) electrolyte. Thus, FR-ILPU is argued to provide potential for the practical application with high safety lithium batteries.

High-Efficient Flame-Retardant Finishing of Cotton Fabrics Based on Phytic Acid.

In this study, an efficient phosphorus-containing flame retardant, PAPBTCA, was synthesized from phytic acid, pentaerythritol, and 1,2,3,4-butane tetracarboxylic acid, and its structure was characterized. PAPBTCA was finished on cotton fabrics by the pad-dry-curing process, and the flame retardancy, flame-retardant durability, and wrinkle resistance of the obtained flame-retardant fabrics were investigated. It should be noted that the heat release rate value of the flame-retardant cotton fabrics treated with 200 g/L PAPBTCA decreased by 90% and its excellent flame retardancy was maintained after 5 washing cycles. Meanwhile, the wrinkle resistance of flame-retardant cotton fabrics has been significantly improved. In addition, compared with the control, the breaking force loss of PAPBTCA-200 in the warp and weft directions was 24% and 21%, respectively. This study provides a new way to utilize natural phosphorus-based flame retardants to establish multifunctional finishing for cotton fabrics.

A Bridge-Linked Phosphorus-Containing Flame Retardant for Endowing Vinyl Ester Resin with Low Fire Hazard

The high flammability of vinyl ester resin (VE) significantly limits its widespread application in the fields of electronics and aerospace. A new phosphorus-based flame retardant 6,6'-(1-phenylethane-1,2 diyl) bis (dibenzo[c,e][1,2]oxaphosphinine 6-oxide) (PBDOO), was synthesized using 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and acetophenone. The synthesized PBDOO was further incorporated with VE to form the VE/PBDOO composites, which displayed an improved flame retardancy with higher thermal stability. The structure of PBDOO was investigated using Fourier transformed infrared spectrometry (FTIR) and nuclear magnetic resonances (NMR). The thermal stability and flame retardancy of VE/PBDOO composites were investigated by thermogravimetric analysis (TGA), vertical burn test (UL-94), limiting oxygen index (LOI), and cone calorimetry. The impacts of PBDOO weight percentage (wt%) on the flame-retardant properties of the formed VE/PBDOO composites were also examined. When applying 15 wt% PBDOO, the formed VE composites can meet the UL-94 V-0 rating with a high LOI value of 31.5%. The peak heat release rate (PHRR) and the total heat release (THR) of VE loaded 15 wt% of PBDOO decreased by 76.71% and 40.63%, respectively, compared with that of untreated VE. In addition, the flame-retardant mechanism of PBDOO was proposed by analyzing pyrolysis behavior and residual carbon of VE/PBDOO composites. This work is expected to provide an efficient method to enhance the fire safety of VE.

Synergistic Function between Phosphorus-Containing Flame Retardant and Multi-Walled Carbon Nanotubes towards Fire Safe Polystyrene Composites with Enhanced Electromagnetic Interference Shielding.

As a universal polymer material, polystyrene (PS) is widely applied in electrical devices and construction. Thus, it is necessary to improve the flame retardancy and electromagnetic shielding properties of PS material. In this work, PS/silicon-wrapped ammonium polyphosphate/Inorganic acid-treated multi-walled carbon nanotubes composites (PS/SiAPP/aMWCNT, abbreviated as PAC) were prepared via methods of filtration-induced assembly and hot-pressing. Morphology and structure characterization demonstrated that SiAPP and aMWCNT had good dispersion in PS and excellent compatibility with the PS matrix. Thermogravimetric analysis revealed that the addition of aMWCNT to PS improved its thermal stability and carbon-forming characteristics. The peak heat release rate, the peak carbon monoxide production rate, and the peak smoke production rate of the PAC10 composite decreased by 53.7%, 41.9%, and 45.5%, respectively, while its electromagnetic shielding effectiveness reached 12 dB. These enhancements were attributed to the reason that SiAPP and aMWCNT synergistically catalyzed the char generation and SiAPP produced free radical scavengers and numbers of incombustible gases, which could decrease the oxygen concentration and retard the combustion reaction. Therefore, the assembled PS/SiAPP/aMWCNT system provides a new pathway to improve the flame retardant and electromagnetic shielding properties of PS.

Carbon Dots as smoke suppression agents for the reduction of CO release in combustion and improvement of UV resistance towards Phosphorus-containing polyester

2-Carboxyethyl(phenyl) phosphinic acid (CEPPA) is an effective phosphorus-containing flame retardant for PET. However, the release of poisonous and harmful smoke increases when CEPPA is added to PET matrix (CEPPA-PET) during the combustion process. To address this, biomass gelatin-based Carbon Dots (gCDs) was adopted as nontoxic green smoke suppression agent. When the gCDs was copolymerized into CEPPA-PET matrix by in situ polymerization (CEPPA-gCDs-PET), the peak smoke production rate was reduced by 59.38% and the CO yield was decreased by 13.83%. It was found the limited oxygen index of CEPPA-gCDs-PET rose to 31% from 21% and could achieve a V-0 rating in the UL-94 test when the content of gCDs and CEPPA were only 1.0 wt% and 5.0 wt%, respectively. What is more, in comparison with neat PET, the peak heat release rate significantly decreased by 42.66% and the total heat release was reduced by 48.10%, the peak smoke production rate is also reduced by 59.38%. Besides, the tensile strength of CEPPA-gCDs-PET increased by 11.93% for CEPPA-PET. At the same time, the addition of gCDs was beneficial for the improvement of UV resistance for CEPPA-PET, and the transmittance of sleeves prepared from the fiber of CEPPA-gCDs-PET is less than 5% from 240 nm to 400 nm. Thus, a higher efficiency flame retardant, mechanical enhancement and UV resistance system was constructed with only 5 wt% CEPPA and 1 wt% gCDs toward CEPPA-PET copolymer.

DOPO-BASED FLAME RETARDANT: PREPARATION AND ITS APPLICATION IN SILICONE RUBBER BLENDS

ABSTRACT In this study, a phosphorus-containing flame retardant, polybis(4-hydroxypheyl)-2-(6-oxo-6-H-dibenzodibenzo [c,e][1,2] oxaphosphino-6-yl) methylene succinate (PHDO) was prepared by melt condensation between (6H-dibenz[c,e][1,2]oxaphosphorin-6-ylmethyl)-p-oxide-butanedioic acid (DDP) and 1,4-benzene dimethanol (PXG). Then, Fourier transform infrared spectroscopy (FTIR) and hydrogen nuclear magnetic resonance (1H NMR) were used to characterize the structure of this novel additive. It was added to silicone rubber (SR) in different proportions, and the flame retardant properties together with tensile behaviors of the SR blends were investigated. Results showed that the thermal stability was improved and the burning rate was slowed down after addition of this novel flame retardant. Vertical burning test, cone calorimetric evaluation, and limited oxygen index (LOI) measurement of the samples revealed that the SR with 15 phr of PHDO owned the best flame retardant properties and may pass UL-94 V-0 grade. This improved flame retardant performance may be ascribed to the formation of dense carbon layers, which effectively prevented the surface oxidation and inhibited combustion of the silicone matrix.

A bio-based macromolecular phosphorus-containing active cotton flame retardant synthesized from starch

A novel phosphorus-containing flame retardant, ammonium starch phosphate (ASTP) based on biomass starch, was synthesized for cotton fabrics, and its structure was characterized by 1D and 2D NMR. The limiting oxygen index (LOI) of the cotton fabric treated with 30 % ASTP reached 45.2 %, and the LOI remained at 32.1 % after 50 laundry cycles, indicating that the cotton fabrics treated with ASTP had a high flame retardancy and semi-permanent wash durability. The semi-permanent wash durability, Fourier transform infrared spectroscopy (FT-IR) and the SEM results suggested ASTP was grafted on the surface of cotton fibers by P-O-C covalent bonds. Vertical flammability, the thermogravimetry (TG) and cone calorimetry results showed that the cotton fabrics treated with ASTP had excellent flame retardancy. There were some reductions in the physical properties of the treated cotton fabric. Overall, these results suggested that starch can replace polyhydric alcohols to prepare a more durable formaldehyde-free P-based flame retardants.

Polybenzoxazine binders for polymeric composite materials

Phosphazene-containing benzoxazine compounds based on diamines of various structures were obtained as a result of the work performed. The resulting compounds were characterized by 1H NMR spectroscopy, the thermal and rheological properties of benzoxazines based on diamines were studied, and data of flammability were presented. The effect of the structure of the initial diamine on the properties of the resulting monomer and polymer has been studied. The curing kinetics of compositions of benzoxazines with different contents of phosphorus-containing flame retardant catalysts based on hexachlorocyclotriphosphazene and m-toluidine was studied. The synthesized monomers and the resulting compositions of benzoxazines with flame retardant catalysts can be used as heat and fire resistant binders for polymer composite materials, as well as hardeners for epoxy resins.

A triazine-based hyperbranched char-forming agent for efficient intumescent flame retardant Poly(lactic acid) composites

It still remains a challenge to address the issues of high flammability, severe dripping and toxicants emission of poly(lactic acid) (PLA) under fire conditions, restricting its widespread usage. In this work, a triazine-based hyperbranched charring agent (TBHCA) was synthesized via the polymerization of A2 + B3 type reaction, and further incorporated into PLA matrix in combination with ammonia polyphosphate (APP) for achieving fire hazard suppression. The resultant PLA/APP/TBHCA composites exhibited superior fire safety, including low heat release, reduced carbon monoxide (CO) emission and anti-dripping behavior, as proved by the results of limiting oxygen index (LOI) and cone calorimeter tests. With the incorporation of 13.33 wt% TBHCA and 6.67 wt% APP into PLA matrix, the LOI value of PLA composite reached 29% and passed UL-94 V0 rating in vertical burning test. Additionally, significant reductions in peak heat release rate (by 54.7%), peak CO production (by 60.2%) and anti-dripping performance can be acquired, resulting from the synergistic effect between the phosphorus-containing flame retardant and triazine-based hyperbranched char-forming agent. This work provides a simple approach to the construction of phosphorus-containing and triazine-based intumescent flame retardant systems for polymeric materials.

Synergic effects of dimethyl methylphosphonate (DMMP) and nano-sized montmorillonite (MMT) on the flammability and mechanical properties of flax fiber reinforced phenolic composites under hydrothermal aging

In this study, a phosphorus-containing flame retardant (FR) DMMP was applied to solve the flammability of flax fiber reinforced phenolic composites (FFRPCs), and the phenolic resin was further modified with nano-sized MMTs in order to enhance the flame retardancy. The water absorption performance of the composites was obtained by weighing method and the flammability of the composites was evaluated through the vertical burning test and limiting oxygen index (LOI) test. The effect of water absorption on the interlaminar properties of the composites was investigated. Then, the morphology of the composites and thermal stability of the composites were analyzed with the aid of scanning electronic microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and cone calorimeter test before and after water immersion. The results revealed that using DMMP to pretreat flax fiber is a simple and effective method to improve the flame retardancy of FFRPCs. Adding MMTs into the phenolic resin facilitated the formation of more carbonization layers within the composites during burning, which would synergistically retard flame with the DMMP. On the other hand, it restrained water absorption of the composites and hindered the precipitation of DMMP from the composites to some extent. Therefore, the effects of water absorption on the reduction of the flammability and mechanical properties of DMMP/MMT treated composites were less than those being merely treated by DMMP due to less water absorption of the composites by adding MMTs.

A phosphorus-containing flame retardant with thermal feature suitable for polyamide 6 and its filaments with enhanced anti-dripping performance

The absence of flame retardant with suitable thermal feature and high flame retardancy has greatly limited the development of flame-retardant polyamide 6 (PA6). In this work, a phosphorus-containing flame retardant (CBPB) with appropriate flame responsive nitrile groups was synthesized, and its melting temperature, cross-linking temperature and initial degradation temperature exactly matched the thermal feature of flame retardant suitable for PA6. PA6/CBPB composites (FR-PA6s) were prepared by melt-blending various contents of CBPB into PA6 matrix. The UL-94 and limiting oxygen index (LOI) of FR-PA6s reached V-0 and 32.0% respectively once 8 wt% of CBPB was added to PA6 matrix. As a representative, FR-PA6-6 (6 wt% of CBPB in PA6 matrix) was successfully melt-spun into filaments with good mechanical properties. The filament strand was self-extincted within 4 s and only one droplet was generated after ignited in the vertical burning tests. The corresponding anti-dripping and flame-retardant mechanism were also explored. Suppression of melt-dripping of FR-PA6s was formed due to the chemical cross-linking of nitrile groups of CBPB at ∼290 °C, which significantly exceeded the general processing temperature of PA6 (∼260 °C) and so the processability of FR-PA6s was slightly affected. The enhanced flame resistance of FR-PA6s was contributed to the quenching effect of PO· and PO2· radicals as well as the diluting effect of NH3 in the gas phase.

Effect of phosphorus-containing modified UiO-66-NH2 on flame retardant and mechanical properties of unsaturated polyester

A novel phosphorus-containing flame retardant PZN@UiO-66-NH2 was synthesized by covalent bonding between HCCP and UiO-66-NH2, and applied in unsaturated polyester (UPR). The Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron energy spectra (XPS), scanning electron microscopy (SEM) was used to confirm the chemical structure of PZN@UiO-66-NH2. The appearance of new P-N-C bond indicated that HCCP was successfully reacted with UiO-66-NH2. The thermal stability and the flame-retardant properties of the UPR composites were characterized by thermogravimetric analysis (TGA), limiting oxygen index (LOI) and cone calorimeter test. The limiting oxygen index (LOI) of UPR composite with 4 wt% PZN@UiO-66-NH2 can reach 23.9%. Compared with pure UPR, the peak heat release rate (PHRR) value, total heat release (THR) value and average effective heat of combustion (av-EHC) value of UPR composite with 4 wt% PZN@UiO-66-NH2 dropped by 36.53%, 28.70%, 23.50%, respectively. The addition of PZN@UiO-66-NH2 slightly improved the impact performance of UPR composite. PZN@UiO-66-NH2 can solve UiO-66-NH2's agglomeration dilemma in UPR to some extent.

Modeling the formulation of the PVC cable composition

Increasing the fire-retardant characteristics of polymeric cable materials has attracted the close attention of experts all over the world for many years, since fires are often associated with the ignition of cable products, followed by the spread of fire through cable communications. In this regard, the development of new modern formulations of fireproof compositions with improved performance properties is especially relevant for the production of PVC cable composites. The article describes the production of a new phosphorus-containing flame retardant phenyldixylol phosphate and investigated its physicochemical properties. The new flame retardant was tested in an industrial formulation of a PVC cable composition using dibutoxyethyl adipate as a plasticizer. Using the methods of correlation-regression analysis and optimization, the optimal ratio of the resulting additive and tricresyl phosphate was selected, which provides the best technological and operational parameters of the PVC composite.

Eco-friendly thermally insulating cellulose aerogels with exceptional flame retardancy, mechanical property and thermal stability

BackgroundEco-friendly thermally insulating cellulose aerogels made from environmentally friendly resources are very attractive in materials chemistry, but the high flammability limits their application. MethodHerein, a novel phosphorus-containing flame retardant modifying agent (DOPO-IA) was incorporated into the cellulose nanofiber aerogel and the cellulose composite aerogels were prepared by esterification and followed by a freeze-drying process. FindingsThe thermal conductivity of the resultant cellulose composite aerogels was in the range of 28.6–31.2 mW/(mK). Meanwhile, the cellulose aerogels modified with DOPO-IA showed significantly enhanced thermal stability, mechanical property, and flame retardant performance compared with the pure cellulose aerogel. The CNF-DI-3 showed a high char residue (19.8 wt%) at 700 °C, which was 187% higher than CNF. Specifically, CNF-DI-3 exhibited remarkable reductions in its PHRR and THR values which were 67% and 60%, respectively, as compared to those of CNF. In summary, it is of significance to synthesize mechanically robust and flame-retardant cellulose aerogels.