Retarding Effect Research Articles

Synergetic effect of superabsorbent polymer and shrinkage reducing admixture on the properties of alkali-activated slag binders

This research is to investigate the synergistic effects of superabsorbent polymer (SAP) and shrinkage-reducing admixture (SRA) on autogenous shrinkage, hydration and microstructure of alkali-activated slag system (AAS). Results revealed that the addition of SRA reduced the absorption capacity of SAP, resulting in a smaller size distribution of macrovoids throughout the AAS matrix. Nevertheless, the presence of SAP affected the ability of SRA to effectively reduce the surface tension of the pore solution of AAS. Instead, the addition of SAP resulted in an increase in surface tension by up to 14%. This phenomenon can be explained by the hydrophobic interactions between SAP networks and SRA molecules. The combination of SAP and SRA in AAS exhibited greater effectiveness in controlling autogenous shrinkage compared to using SRA alone, resulting in a reduction of around 53% compared to 46%. On the other hand, incorporating only SAP proved to be more effective, leading to a higher reduction of 90%. However, this combined effect is reported to be counteractive and dependent on the content of each component. Moreover, the hybrid system of SAP and SRA demonstrates a pronounced retardation effect on AAS hydration. The XRD patterns showed no new reaction products were formed. As revealed by SEM analysis, the microstructure of AAS containing SAP and SRA exhibited a distribution of microvoids ranging from 5 to 50 μm. This can explain the reduction of the compressive strength by incorporation a high content of SAP combined with SRA. However, incorporating a lower dosage of SAP is advantageous when combined with SRA in AAS systems. Finally, the integration of SAP and SRA had a positive influence on the properties of AAS mortars, thus compensating for the limitations of each constituent.

Recycling Local Waste Glass Bottles into Cement Paste: Effect on Hydration, Microstructure, and CO2 Emission.

Large amounts of waste glass are generated along with the manufacturing of glass products, causing detrimental effects on the environment. Through crushing and ball-milling, waste glass powder (WGP) can be acquired from glass bottles and has been suggested in cementitious systems due to its potential pozzolanic activity. To better understand the impact of WGP on cementitious composites, experimental tests of rheology, heat of hydration, and strength development were conducted on cement pastes with and without WGP. Results show that the rheological performance of cement paste is improved when WGP with particles passing through 80 μm sieves is incorporated. The retarding effect and pozzolanic reaction were observed through X-ray diffraction patterns and thermo-gravimetric parameter analyses. A calcium hydroxide (CH) content calculation further confirms the secondary reactivity of WGP in cement pastes. Compared with the samples without WGP, the normalized CH content of binder per unit mass containing 35% WGP decreased by 21.01%, 24.94%, and 27.41% at the ages of 1, 28, and 90 days, respectively, which contributes to late-age strength development of pastes. At the same time, the hydration per unit of cement was increased by 21.53%, 15.48%, and 11.68%, which improved the cement efficiency. In addition, WGP particles provide nuclei for hydration products, facilitating the subsequent growth of C-S-H and strength development in late ages. Based on value engineering analysis, WGP was found to reduce the impact of Portland cement on the environment by 34.9% in terms of carbon dioxide emissions, indicating a bright prospect for WGP in the cement industry.

Synthesis of aluminum bis(hydroxy‐phenyl‐methyl)phosphinate and its synergistic flame retardant mechanism in PLA

AbstractIn this paper, we report on the synthesis of a new aluminum bis(hydroxy‐phenyl‐methyl)phosphinate, AlBPi, under mild reaction conditions. The product structure was confirmed via characterization, and its thermal stability and flame retardant properties were assessed. To improve the flame retardant properties, we employed ammonium polyphosphate (APP) as a synergist with AlBPi. The PLA composite material containing 10% AlBPi and 5% APP achieved an LOI of 28.1% and a UL‐94 rating of V‐1. Cone calorimetry tests showed a significant reduction in PHRR, THR, PSPR, and TSP for the PLA/AlBPi/APP composite compared to the pure and PLA/AlBPi materials. SEM analysis revealed a continuous and dense char layer on the residual surface of the synergistic flame retardant sample. AlBPi and APP exhibited excellent synergistic flame retardant effects, with both releasing a large amount of PO·free radicals. APP was also able to release inert gas, exhibiting excellent flame retardant effects in the gas phase. Additionally, APP improved the charring performance of AlBPi and formed a compact char layer on the material surface, achieving good flame retardant effects in the condensed phase. Therefore, the AlBPi and APP synergistic flame retardant system can be considered a viable flame retardant additive for PLA.Highlights A novel flame retardant AlBPi was synthesized. AlBPi and APP demonstrate good synergistic flame retardant performance in PLA. AlBPi and APP play a flame retardant role in both gas and condensed phases.

The early hydration and rheological characteristics of cement paste containing co-combustion fly ash

In this study, the early hydration and rheological characteristics of cement paste containing co-combustion fly ash (CCFA) were studied by using isothermal calorimetry, low-field NMR (LF-NMR), and rheological tests, and the differences between CCFA/cement system and the traditional binding system made with coal fly ash (CFA) were analyzed. The results indicate that co-combustion fly ash has a retarding effect on the early hydration of the cement. This effect becomes more pronounced as the dosage of fly ash increases from 10% to 30%. Additionally, the early hydration rate of samples containing CCFA was found to be faster compared to samples with CFA, even when the same admixture was used. The T2 spectrum analysis reveals that fly ashes primarily influence the early hydration characteristics by affecting the consumption of capillary water. As the admixture of fly ash increases, there is a reduction in moisture loss. The pattern of moisture evolution exhibits a strong correlation with the heat of hydration. At 72 h, the relaxation characteristics of both CCFA and CFA samples were found to be similar. Moreover, the rheological properties of the cement paste are influenced by factors such as the type and admixture amount of fly ash, as well as the degree of hydration. With an increase in the amount of fly ash blending, the rheological properties exhibit an increase as well. Specifically, CCFA samples display higher plasticity compared to CFA samples, even when the same admixture amount is used. The results of different analytical methods in the study were consistent.

Synthesis of a novel biobased tetrapod zinc oxide and synergy with melamine cyanurate to improve the flame retardancy and mechanical properties of epoxy resins

In this paper, based on phytic acid (PA), chitosan (CS) and tetrapod zinc oxide (TZ), a biobased flame retardant material (TZ@PA@CS) was synthesized by solution self-assembly method. A halogen-free green intumescent epoxy resin (EP) flame retardant system was composed of TZ@PA@CS and melamine cyanurate (MCA), and its thermal stability, flame retardancy, mechanical properties and related mechanism were studied in detail. The results show that the thermal stability of EP composites is improved after adding 3 wt% TZ@PA@CS and 5 wt% MCA into EP, and it can easily pass the UL-94 V-1 grade. At the same time, compared with pure EP, its peak heat release rate decreased by 44%, and the char residue rate increased by about 100% in cone calorimeter test. It is found that TZ@PA@CS and MCA have outstanding grading and synergistic flame retardant effects, and can form a dense, expansive and phosphorus-containing char layer. Besides, its impact and compression strength and compression deformation are increased by 41%, 39% and 155% respectively, which shows that it has good energy absorption, impact toughness and compression strength. This work provides a simple strategy for preparing biobased EP composites with excellent flame retardant properties, impact resistance and compression resistance.

Investigation of the Pozzolanic Activity Improvement of Yellow Phosphorus Slag with Thermal Activation.

Yellow phosphorus slag (YPS) is a byproduct from the production of yellow phosphorus. It has potential pozzolanic activity and can be used as a supplementary cementitious material. However, the early strength of cement mortar decreases significantly with increasing YPS dosage, which restricts the utilization of YPS in cement and concrete. This study aimed to increase the pozzolanic activity of YPS ash by thermal activation. The strength method, alkali dissolution method and polymerization degree method were used to evaluate the effect of thermal activation at different temperatures on the pozzolanic activity of YPS ash. The results showed that YPS ash calcined at 800 °C helps to enhance the early strength because the fluorine in cuspidine (Ca4Si2O7F2) is insoluble, reducing the retarding effect on the mortar. The higher late strength of YPS ash calcined at 100 °C was due to the low polymerization degree of [SiO4]. The pozzolanic activity of YPS ash is positively correlated with the dissolution concentration of (Si + Al) and the compressive strength and negatively associated with the polymerization degree. This paper shows a possibility for the large-scale utilization of YPS.

Modification and mechanism of polymer in high-performance concrete with full aeolian sand: An integrated macro-to-micro perspective

Producing high-performance concrete with full aeolian sand (FA-HPC) can achieve efficient utilization of desert resources to combat the shortage issue of aggregates. However, low water–cement ratio and high fine content result in a high risk of brittleness and durability in this concrete. Herein, polyacrylamide (PAM) and styrene-butadiene rubber latex (SBR) were incorporated into the FA-HPC to optimize its performance. Effects and mechanisms modifying the FA-HPC with polymers were compared and studied from macro-to-micro perspectives, with respect to workability, mechanical properties, durability, adsorption, and hydration. The results revealed a negative correlation with the PAM content (contrary to the SBR content) in fluidity and the content-dependent extension in setting time. For strength and shrinkage, the best performance was observed in the PAM-modified FA-HPC at 0.05% content presenting the substantial mitigation in brittleness. Moreover, regarding chloride resistance, SBR showed a more positive effect than PAM, with a 40.9% improvement at 10% content. From the micro-perspective observation, the retarding effect at early stages and acceleration during the late hydration process were verified by phase analysis. The polymer film and polymer bridge as well as the refined pore structure were the primary contributing factors to the performance improvement. Overall, compared to SBR modification, PAM modification with stronger adsorption capacity balances the comprehensive performance improvement of FA-HPC better at 0.05% content. Additionally, the specificity of the FA-HPC and the difference in modification behavior were discussed. This research allows the material-composition optimization of FA-HPC and further promotes the wide application of aeolian sand-based cementitious materials.

The effect of flame retardants on the fire technical characteristics of recycled textiles

The paper deals with the fire technical characteristics of insulation panels made of recycled technical textiles from the automotive industry. The introductory part focuse an of the use of recycled textiles, a description and division of technical textiles, a description of the examined material and its composition, combustion processes, and the method of handling waste textiles. The monitored characteristics were the determination of the ignitability of the material, the gross calorific value as well as the radiant heat resistance. The measurements were carried out on samples from recycled technical textiles before and after their treatment with flame retardants (Isonem Anti-fire Solution, Ecogard B45, HR Prof, woven carbon foil, non-woven carbon foil). The best results in the ignitability test after treatment with liquid flame retardants were obtained after treatment with Ecogard B45. The results show that when flame retardants are used, the released heat during the combustion of the monitored materials treated through the dipping method is significantly lower from 13.7 MJ/kg to 23.7 MJ/kg. The lowest gross calorific values were achieved when using liquid flame retardant HR Prof when applied by dipping. The proportion of material that did not burn was very low (4.61 to 5.63%). After exposure to radiant heat for 10 min, the highest mass loss was 13.6% (dipping in Ecogard B45) and the smallest 1.8% (non-woven carbon foil). Based on results, it shows that flame retardant ECOGARD® B45 for the insulation material Senizol AT XX2 TL60 made from recycled technical textiles is the most suitable fire protection.

Synergistic fire retardancy of melamine resin modified with pentaerythritol and ammonium polyphosphate in PP

AbstractThe synergistic fire retardancy of modified melamine resin with pentaerythritol (MF‐PER, a novel green and effective triazine charring agent), and ammonium polyphosphate (APP) in polypropylene was investigated by UL‐94 test, LOI measurement, and cone calorimetry test. It is found that the synergism of MF‐PER is obviously better than pentaerythritol (PER). MF‐PER/APP imparts a fire retardancy mainly by the following mode: in burning process, MF‐PER, and APP are first pyrolyzed respectively into polyols and polyphosphoric acid, which is esterified to form phosphoric ester, and the inert gases make the molten residues foaming; When the temperature increases, and polyphosphoric acid is dehydrated to polymetaphosphoric acid, which dehydrates phosphoric ester to form an intumescent char layer, inducing a fire retardant effect by barrier effect. The graphitization degree of the cone calorimetry test residues of the FR‐PP with MF‐PER is higher than that with PER, which leads to a better synergism.Highlights Melamine formaldehyde resins modified with pentaerythritol (MF‐PER) as a novel triazine charring agent was designed and synthesized. MF‐PER is synthesized by solid phase method and using hexahydroxymethyl melamine (HMM) instead of cyanuric chloride as raw material, so the emission of three wastes in its synthesis process is very little, only a small amount of formaldehyde and water are produced. MF‐PER has excellent synergistic fire retardancy with APP in polypropylene. The highly efficient and environmentally benign charring agent show great potential for developing more efficient and eco‐friendly IFR.

An overview of the (eco)toxicological effects of flame retardants emerging in water and sediment

An overview of the (eco)toxicological effects of flame retardants emerging in water and sediment

Development of a simplified human embryonic stem cell-based retinal pre-organoid model for toxicity evaluations of common pollutants

Objective To explore the retinal toxicity of pharmaceuticals and personal care products (PPCPs), flame retardants, bisphenols, phthalates, and polycyclic aromatic hydrocarbons (PAHs) on human retinal progenitor cells (RPCs) and retinal pigment epithelial (RPE) cells, which are the primary cell types at the early stages of retinal development, vital for subsequent functional cell type differentiation, and closely related to retinal diseases. Materials and methods After 23 days of differentiation, human embryonic stem cell (hESC)-based retinal pre-organoids, containing RPCs and RPE cells, were exposed to 10, 100, and 1000 nM pesticides (butachlor, terbutryn, imidacloprid, deltamethrin, pendimethalin, and carbaryl), flame retardants (PFOS, TBBPA, DBDPE, and TDCIPP), PPCPs (climbazole and BHT), and other typical pollutants (phenanthrene, DCHP, and BPA) for seven days. Then, mRNA expression changes were monitored and compared. Results (1) The selected pollutants did not show strong effects at environmental and human-relevant concentrations, although the effects of flame retardants were more potent than those of other categories of chemicals. Surprisingly, some pollutants with distinct structures showed similar adverse effects. (2) Exposure to pollutants induced different degrees of cell detachment, probably due to alterations in extracellular matrix and/or cell adhesion. Conclusions In this study, we established a retinal pre-organoid model suitable for evaluating multiple pollutants’ effects, and pointed out the potential retinal toxicity of flame retardants, among other pollutants. Nevertheless, the potential mechanisms of toxicity and the effects on cell detachment are still unclear and deserve further exploration. Additionally, this model holds promise for screening interventions aimed at mitigating the detrimental effects of these pollutants.

Effect of Retarders on the Reactivity and Hardening Rate of Alkali-Activated Blast Furnace Slag Grouts.

Sodium silicate-activated slags have the potential to harden quickly, which limits their practical use in grouting and deep soil mixing works. The open time of grouts is defined as the time period when their rheological properties allow their storage, pumping, and injection into the soil. In this work, the impact of the H2O/Na2O ratio and two acids (citric and boric acid) on the reactivity and hardening rates of slag-based grouts was studied. The H2O/Na2O ratio had a minimal impact on the open time but prolonged the setting time, as observed by ultrasonic characterization. Both acids were effective in delaying the structuration time, as revealed by oscillatory rheology and reaction advancement; however, they caused a decrease in the elastic modulus. Adding the acids resulted in a decrease in the pH of the medium, which may be linked to the extended open time. The analysis of the ion concentration of Ca, Si, and Al disclosed the mode of action of the two retarders.

Investigation of Plasticity Effects on Growing Fatigue Cracks Using the CJP Model of Crack Tip Fields.

A growing fatigue crack gives rise to a plastic enclave that envelops the crack and can exert a shielding effect on the crack from the global elastic stress field driving fatigue propagation. This work presents the potential of the CJP model of crack tip fields to investigate the plasticity-induced shielding effects on growing fatigue cracks as well as its ability to characterise the size and shape of the plastic zone generated at the tip of a growing fatigue crack. The model was specifically developed to consider the influence of the plastic enclave generated around a fatigue crack on the surrounding elastic material. Different aspects related to fracture mechanics and its implications for fatigue crack growth have been investigated, namely plasticity-induced crack shielding, the retardation effect induced on fatigue crack growth due to the application of an overload and the estimate of the size and shape of the crack tip plastic zone. The model has been successfully applied by analysing displacement fields experimentally measured by DIC in different CT specimens made of 2024-T3 aluminium alloy and commercially pure titanium. Results presented in this work intend to contribute to a better understanding of the shielding effects during fatigue crack growth.

Phosphorus‐containing hyperbranched polysiloxanes intercalated graphene oxide and their flame retardant effect on epoxy resin

AbstractIntrinsic flammability significantly impedes practical applications of epoxy (EP), despite many merits. Intercalation‐functionalized graphene oxide (GO) has shown excellent performance in flame retardancy studies of polymers, but research investigating the effect of layer spacing on the flame‐retardant performance of polymers is still lacking so far. Therefore, three GO flame retardants with different layer spacing were prepared to flame retardant EP. When the layer spacing of GO is 1.09 nm, the heat and smoke release from EP composites is effectively suppressed. This is attributed to the barrier effect and maze effect of GO as well as the synergistic effect between the intercalator and GO. Analysis shows that the layer spacing of GO affects the flame retardancy of the composite by influencing the formation of protective char layer.

Hydrogen damage behaviour of X80 steel under high voltage direct current interference

In this paper, the hydrogen damage behaviour of X80 steel under HVDC interference was investigated at different sites and applying voltages. The effect of application of a sustained tensile load during the interference testing on the ductility of steel was also studied. It was found that the interference modestly but consistently reduced the elongation of the steel, with dimples still dominating on the fracture surfaces. Application of a sustained tensile load significantly reduced the ductility of the steel, resulting in cleavage fracture dominant on the fracture surfaces on these samples. It also clearly increased the yield strength of the steel. The test results were explained by hydrogen trapping at dislocations and their retardation effect on dislocation movement during the SSRT.

Synthesis and application of a halogen-free epoxy resin flame retardant curing agent

In this study, the intermediate of SPDPC flame retardant curing agent was successfully synthesized through the reaction between phosphorus oxychloride and pentaerythritol under the catalysis of 4-dimethylaminopyridine. Using 1,2-propylenediamine and the prepared SPDPC, a novel phosphorus and nitrogen flame retardant curing agent named poly1,2-propylenediamine pentaerythritol diphosphate (PDS) was successfully synthesized. The target product was subjected to characterization using infrared spectroscopy, mass spectrometry, hydrogen NMR spectroscopy and thermogravimetric analysis. The molecular structure of the product was determined and its decomposition temperature curve obtained, leading to the conclusion that it could be cured at high temperatures. DDS was selected as the curing agent for epoxy E-51, the specific curing conditions were obtained by DSC test. Subsequently, E-51, DDS and PDS were mixed for high temperature curing resulting in obtaining test spline of PDS-E-51 flame retardant composite material. Then, the flame retardancy and mechanical properties of the spline were tested. It was observed that pure EP cured by DDS had an LOI of only 19.5%, indicating its flammability. However, upon addition of PDS as a flame retardant, the LOI significantly increased with 20 parts resulting in an LOI of 29.7%. The addition of 25 parts results in an increase in limiting oxygen index to 30.3%, while the tensile strength and impact strength are measured at 38.27 MPa and 5.087 kJ/m2 respectively. The CCT test shows that the addition of PDS can significantly reduce the HHR and THR of the system. CCT digital photos show that the addition of PDS can make the combustion residue of the system expand obviously, showing a good expansion and flame retardant effect. TG-FTIR gas phase infrared absorption indicates that the addition of PDS can reduce the concentration of combustible gas in the combustion process. Test results indicate that the mechanical properties of PDS-E-51 flame retardant composites experience a certain degree of decline, but with increasing amounts of PDS curing agent added, their flame retardancy is significantly enhanced.

Eco-friendly lightweight composite prepared with a geopolymer and wheat straw

Agricultural waste shows promise for use in lightweight building materials. The combination of a geopolymer and wheat straw (WS) is adopted to produce a kind of eco-friendly lightweight composite. Using WS pretreated with sodium hydroxide (NaOH) and sodium metasilicate (Na2SiO3) solutions, the influence of WS on the properties of the geopolymer–WS composite (GWSC) is investigated. The pretreated WS avoids the retarding effect of the untreated WS on the hydration of the geopolymer and even presents an accelerating effect. Increasing the content of pretreated WS generally results in a reduction in apparent density and strength. A GWSC with an apparent density of 1000–1500 kg/m3 can be prepared, corresponding to a 28-day compressive strength between 5 and 25 MPa. The water absorption linearly increases with the increase in the pretreated WS content, while an appropriate amount of the pretreated WS can enhance the water resistance of the GWSC. A WS/fly ash ratio lower than 8% can produce a GWSC with qualified thermal insulation performance. Alkaline treatment, particularly sodium hydroxide treatment, significantly improves the bonding strength between the fiber and the geopolymer matrix. In addition, pretreated WS saturated with sodium hydroxide and sodium metasilicate solutions is beneficial to the fluidity of the geopolymer–WS mixture and could act as an internal curing agent for enhancing the hydration of the geopolymer.

Flame retardancy and smoke suppression effect of an organic–inorganic hybrid containing phosphaphenanthrene‐modified magnesium hydroxide/zinc borate on epoxy resin

AbstractTo improve the flame retardancy and smoke suppression effect of epoxy resin (EP), a new organic–inorganic hybrid (MH@ZB‐ODOPB) was fabricated. First, hierarchical‐structured particles (MH@ZB) were prepared by gradually depositing zinc borate (ZB) on the surface of magnesium hydroxide (MH) via a heterogeneous deposition process. Second, MH@ZB was modified with 10‐(2,5‐dihydroxyphenyl)‐10‐hydro‐9‐oxa‐10‐phospha‐phenanthrene‐10‐oxide (ODOPB) to obtain MH@ZB‐ODOPB. Finally, the chemical structure and form of MH@ZB‐ODOPB were analyzed via X‐ray diffraction, Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and scanning electron microscopy. The characterization results show that ZB was loaded onto the surface of MH, and ODOPB was grafted on the surface of MH@ZB. The cone calorimetry test results show that when 7.5 wt% MH@ZB‐ODOPB was added into EP, the peak heat release rates, total heat release, total smoke production, and peak smoke production rates decreased by 51.8%, 42.4%, 58.1%, and 66.1%, respectively. Moreover, EP/MH@ZB‐ODOPB exhibited a limiting oxygen index of 33%. These results show that the incorporation of MH@ZB‐ODOPB into EP composites considerably improved the flame retardancy and smoke suppression properties of EP composites. The double action of MH@ZB‐ODOPB in condensed and gas phases was investigated by analyzing the carbon residue and pyrolysis gas. Furthermore, the implementation of ODOPB improves the mechanical properties of EP composites.

Benefiting from the multiple effects of ferrocene and cyclotriphosphazene bi-based hierarchical layered nanosheets towards improving fire safety and mechanical properties of epoxy resin

Epoxy resin (EP) is widely used in automobiles, aerospace, electrical and electronic fields. However, the overloading of flame retardant will heavily deteriorate the mechanical properties of EP. In this paper, flame retardant nanosheets (FH) with hierarchical layered structure was self-assembled by combining ferrocene formaldehyde (Fc-CHO) and hexa-aminophenoxy-cyclotriphosphazene (HACP) through a nucleophilic reaction. The limiting oxygen index (LOI) of the EP/FH2 nanocomposite with a 2 wt% loading of FH increased to 31.3% and the UL-94 V-0 rating was achieved due to the multiple synergistic flame retardant effects between ferrocene and cyclotriphosphazene, as well as the barrier performance of the FH nanosheets. Simultaneously, in the cone calorimeter (CC) test, the peak heat release rate (pHRR) and total smoke production (TSP) were reduced by 30.2% and 19.0% compared with EP, respectively. What's more, toughness of the EP/FH2 nanocomposite were greatly improved owing to the low loading and good compatibility of FH nanosheets in EP. In short, this work provides valuable insights into the design of flame retardant nanosheets and targets to balance the flame retardancy and mechanical properties of EP with low addition amounts.

The coating based on phenolic resin gives rigid polyurethane foam excellent flame retardant properties

AbstractA flame retardant coating was designed and synthesized using phenolic resin (PF), 9,10‐dihydro‐9‐oxa‐10‐phosphazephenanthrene‐10‐oxide (DOPO), and nano‐SiO2 as raw materials. The coating is applied to the surface of rigid polyurethane foam (RPUF) to give it a flame retardant effect. Based on the excellent adhesion of PF, the coating effectively suppresses heat transfer, and the synergistic effect of DOPO and nano‐SiO2 improves the flame retardancy of RPUF. In addition, vertical combustion experiments have shown that when the ratio of DOPO to nano‐SiO2 is 2:1, there is no dripping, the flame is self‐extinguishing, and the internal structure remains basically unchanged, resulting in the best flame retardant effect. The cone calorimetric test shows that the coating can effectively reduce the total heat release and heat release rate of the substrate, and the smoke release rate and total smoke release data show that its smoke suppression effect is significantly improved. Thermogravimetric analysis shows that the coating can effectively improve the residual carbon rate of RPUF, and its mechanical properties are good. This study confirms that coatings based on PF/DOPO/Nano‐SiO2 can effectively improve the flame retardancy of RPUF, providing a potential direction for the development of green insulation materials.