Bio-based Rigid Polyurethane Foams Research Articles

Improved thermal insulation, mechanical properties, energy absorption and flame retardancy of bio-based rigid polyurethane foam modified with calcium hydroxystannate

Improved thermal insulation, mechanical properties, energy absorption and flame retardancy of bio-based rigid polyurethane foam modified with calcium hydroxystannate

Upcycling PVC and PET as Volume-Enhancing Functional Fillers for the Development of High-Performance Bio-Based Rigid Polyurethane Foams

Polyvinyl chloride (PVC) and polyethylene terephthalate (PET) contribute significantly to global plastic waste, with only 9% recycled in recent years. In this work, these plastic wastes were upcycled as functional fillers to improve the rigid polyurethane foam (RPUF) properties. To attain this target, we leveraged the intrinsic polarity of the C=O and C-Cl groups of PVC and PET to induce intermolecular attractions with the N-H groups of the polyurethane matrix, evidenced by the observed IR peak shifts. This enhanced the nucleating effect during foaming, increasing the foams’ compressive strengths by 77% and 22% with the addition of 10% PVC and 5% PET filler, respectively. Furthermore, the addition of PVC and PET fillers increased the foam volume. Thus, the collective utilization of PPW and its corresponding impact on the CO-based RPUF’s properties signifies a reduction in carbon dioxide emissions by 14.15% and 17.52% for PVC and PET, respectively. Moreover, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed improved thermal stability and degradation profiles of the produced RPUFs. Overall, this work highlights potential advancement in environmentally responsible upcycling strategies for common end-of-life plastic wastes, while enhancing rigid foam properties.

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.

Thermal, mechanical property and flame retardant analysis of bio-based rigid polyurethane foam modified with expandable graphite

As an energy-efficient building material, rigid polyurethane foam (RPUF) has attracted attention. However, there are still great challenges in how to easily prepare RPUF materials with good mechanical properties, flame retardant properties, thermal insulation and other properties. In the current work, expandable graphite (EG)-modified lignin-based polyol (RPUF) was prepared by a one-step method. Thermogravimetric analysis was used to study the pyrolysis of modified foams under nitrogen conditions. It was found that the RPUF-4 with an EG of 10 wt% had the highest the apparent activation energy (E), integral procedural decomposition temperature (IPDT), initial temperature and residue rate. And RPUF-4 also had excellent thermal insulation properties. In addition, RPUF-4 exhibited excellent flame retardancy and smoke suppression properties (peak heat release rate (RHRR), total heat release rate (THR) and Ds were 65.46 %, 23.92 % and 45.94 % lower than those of the unadded RPUF, respectively). At the same time, RPUF-4 also had good mechanical properties and energy absorption properties. These results will lay the foundation for the development and application of RPUF in the field of building insulation.

Green flame-retardant rigid polyurethane foam with cobalt hydroxystannate to improve the thermal stability, flame retardancy and smoke suppression properties

The ecological benefits and concerns surrounding fossil fuels had led to increased interest in bio-based rigid polyurethane foam (RPUF). Nonetheless, due to its flammability, it had limited application in various fields. To solve this problem, a green bio-flame retardant, cobalt hydroxystannate (CoSn(OH)6), was prepared and compounded with montmorillonite (MMT) and chick feather protein (CF), and applied to RPUF, which not only realized the regeneration of resources, but also provided RPUF with better thermal stability, flame retardancy and smoke suppression properties. The experimental results showed that when 3 wt% CoSn(OH)6 was added, the RPUF (CF1/MMT3/Co3) had the greatest activation energy. In addition, the peak heat release rate (PHRR) and total heat release (THR) of CF1/MMT3/Co3 decreased by 12.73%, and 11.16% respectively, compared with no CoSn(OH)6. In addition, its Ds decreased by 28.9% and the light transmittance increased by 17.6% compared with the RPUF without CoSn(OH)6. At the same time, its peak smoke production rate (PSPR) and the total smoke release (TSR) decreased by 25% and 18%. And CF1/MMT3/Co3 also had the lowest fire risk evaluation index. This study presented possibilities for practical utilization of the RPUF substances founded on bio-based flame inhibitors.

Liquefaction optimization of grape pulp using response surface methodology for biopolyol production and bio-based polyurethane foam synthesis.

Both environmental and economic disadvantages of using petroleum-based products have been forcing researchers to work on environmentally friendly, sustainable, and economical alternatives. The purpose of this study is to optimize the solvothermal liquefaction process of grape pomace using response surface methodology coupled with a central composite design. After investigating the physicochemical properties of the liquified products (biopolyol) in detail, a bio-based rigid polyurethane foam (RPUF) was synthesized and characterized. The hydroxyl and acid numbers and viscosity values of all the biopolyols were analyzed. According to variance analysis results (%95 confidence range), both the reaction temperature and catalyst loading were determined as significant parameters on the liquefaction yield (LY). The model was validated experimentally in the following reaction conditions: 4.25% catalyst loading, 50 min reaction time, and 165 °C reaction temperature, which yields an LY of 81.3%. The biopolyols produced by the validation experiment display similar characteristics (hydroxyl number: 470.5 mg KOH/g; acid number: 2.31 mg KOH/g; viscosity: 1785 cP at 25 °C) to those of commercial polyols widely preferred in the production of polyurethane foam. The physicochemical properties of bio-based foam obtained from the biopolyol were determined and the thermal conductivity, closed-cell content, apparent density, and compressive strength values of bio-based RPUF were 31.3 mW/m·K, 71.1%, 33.4 kg/m3, and 105.3 kPa, respectively.

Fabrication of green montmorillonite modified bio-based rigid polyurethane foam with improved flame retardancy and enhanced mechanical properties

A low-carbon and sustainable green rigid polyurethane foam was prepared by compounding montmorillonite (MMT) with homemade barium phytate (BAPA). The flame retardancy, thermal stability and mechanical properties of the modified RPUFs investigated using the limiting oxygen index (LOI) method, cone calorimetry (CONE) and thermogravimetry. The results showed that the BAPA/MMT2 composite containing 2 wt% MMT had the highest LOI (25.1 %), and its peak heat release rate (PHRR) and total heat release (THR) were reduced by 14.33 % and 34.68 %, respectively, compared with that of the BAPA/MMT0 material without added MMT. In addition, the smoke production rate (SPR) and total smoke release (TSR) were reduced by 20.54 % and 30.77 %, respectively. BAPA/MMT2 had good flame retardancy and smoke suppression effect. The mechanical properties of BAPA/MMT2 with 2 wt% MMT were improved. The flame retardant mechanism confirmed that BAPA and MMT synergistically improved the quality of the carbon layer. At the same time, phosphorus-containing compounds (PO·), CO2 and water vapor were produced, which diluted the combustible gas in the gas phase and inhibit the flames spread. The current results provided a new strategy for the preparation of high-performance RPUFs.

Investigation of bio-based rigid polyurethane foams synthesized with lignin and castor oil

In this study, polyurethane (PU) foams were manufactured using kraft lignin and castor oil as bio-based polyols by replacing 5–20 wt% and 10–100 wt% of conventional polyol, respectively. To investigate the effects of unmodified bio-based polyols on PU foam production, reactivity and morphology within PU composites was analyzed as well as mechanical and thermal properties of the resulting foams. Bio-based PU foam production was carried out after characterizing the reagents used in the foaming process (including hydroxyl group content, molecular weight distribution, and viscosity). To compare the resulting bio-based PU foams, control foam were produced without any bio-based polyol under the same experimental conditions. For lignin-incorporated PU foams, two types, LPU and lpu, were manufactured with index ratio of 1.01 and 1.3, respectively. The compressive strength of LPU foams increased with lignin content from 5 wt% (LPU5: 147 kPa) to 20 wt% (LPU20: 207 kPa), although it remained lower than that of the control foam (PU0: 326 kPa). Similarly, the compressive strength of lpu foams was lower than that of the control foam (pu0: 441 kPa), with values of 164 kPa (lpu5), 163 kPa (lpu10), 167 kPa (lpu15), and 147 kPa (lpu20). At 10 wt% lignin content, both foams (LPU10 and lpu10) exhibited the smallest and most homogenous pore sizes and structures. For castor oil-incorporated PU foams with an index of 1.01, denoted as CPU, increasing castor oil content resulted in larger cell sizes and void fractions, transitioning to an open-cell structure and decreasing the compressive strength of the foams from 284 kPa (CPU10) to 23 kPa (CPU100). Fourier transform infrared (FT-IR) results indicated the formation of characteristic urethane linkages in PU foams and confirmed that bio-based polyols were less reactive with isocyanate compared to traditional polyol. Thermogravimetric analysis (TGA) showed that incorporating lignin and castor oil affected the thermal decomposition behavior. The thermal stability of lignin-incorporated PU foams improved as the lignin content increased with char yields increasing from 11.5 wt% (LPU5) to 15.8 wt% (LPU20) and from 12.4 wt% (lpu5) to 17.5 wt% (lpu20). Conversely, the addition of castor oil resulted in decreased thermal stability, with char yields decreasing from 10.6 wt% (CPU10) to 4.2 wt% (CPU100). This research provides a comprehensive understanding of PU foams incorporating unmodified biomass-derived polyols (lignin and castor oil), suggesting their potential for value-added utilization as bio-based products.

Combining hyperbranched polyol containing three flame retardant elements, P, N and Si, with expanded graphite to improve the flame retardancy of bio-based rigid polyurethane foam

The preparation of rigid polyurethane foam (RPUF) from vegetable oil and the improvement of its flame retardant properties are of great importance to broaden the application field of RPUF, which can satisfy the green environment and reduce the fire accidents caused by its flammability. In this paper, a reactive hyperbranched flame retardant polyol (DOPO-MASi) containing three flame retardant elements of P, N and Si was prepared by reacting 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), a phosphorus-containing compound, with maleic anhydride, diethanolamine and Triethoxy(3-glycidyloxypropyl)silane (KH-561), respectively, and mixed with expandable graphite (EG) to obtain a vegetable oil-based flame retardant RPUF with the multi-flame retardant system. This foam has excellent flame retardant properties and smoke-suppressing effect, with a limiting oxygen index (LOI) of 30% and a “V-0″ level in the UL-94 vertical burning test, as well as its pHRR, THR, and TSP were reduced by 47.5%, 57.9% and 62.8%, respectively. More importantly, 5% EG/20% FR-RPUF also has good mechanical properties. The above properties provide a reference for the practical application of RPUF in environmental protection and flame retardant.

Effective removal of phenol from polluted water via bio-based rigid polyurethane foams in collaboration with Alcaligenes faecalis

In this study, the removal efficiencies of bio-based rigid polyurethane foams (“RPUFs” group), Alcaligenes faecalis subsp. faecalis NBRC 13111T (“strain” group), and the combined use of RPUFs and A. faecalis subsp. faecalis NBRC 13111T (“RPUFs + strain” group) were investigated. The concentration of NaCl, number of RPUFs, initial pH and initial phenol concentration were sequentially examined. The results showed the adsorption of phenol in “RPUFs” group and “RPUFs + strain” group was improved with the increased number of RPUFs, and the highest adsorption was about 200 mg/L when 40 pieces of RPUFs were used. Under all conditions, the phenol removal efficiency of “RPUFs + strain” group was higher than that of the “strain” group. With the increased concentration of NaCl, the complete removal time of phenol in “strain” group and “RPUFs + strain” group was correspondingly prolonged. In neutral and weakly alkaline conditions, the phenol removal efficiency of “strain” group and “RPUFs + strain” group was much improved, and the phenol-removed time of 500 mg/L of “RPUFs + strain” group was only 30 h at the pH of 7. With the increase of initial phenol concentration, the complete removal time in “strain” group and “RPUFs + strain” group was delayed, especially at the high concentration of 1100 mg/L, the “strain” group had nearly no ability to remove phenol, while the “RPUFs + strain” group could still completely removed phenol at 78 h. The phenol removal mechanism of the “RPUFs + strain” group was attributed to “physical adsorption - biodegradation”.

Effect of Crosslink Density on Thermal Aging of Bio-Based Rigid Low-Density Closed-Cell Polyurethane Foams

Gradual replacement of the traditional raw materials in polyurethane (PU) synthesis by bio-based ones and introduction of environmentally friendly physical blowing agents (PBAs) motivate the analysis of thermal aging of bio-based foams in order to optimize the chemical structure of the PU matrix so that its permeability to PBA is minimized. With the aim of elucidating the effect of the PU chemical structure on thermal aging of foams, rigid low-density closed-cell PU foams were produced solely from bio-based polyols. The effective diffusivities of PBA and atmospheric gasses were evaluated based on the measured thermal conductivity aging of foams and validated by gas chromatography measurements of gas composition in foam cells. Gas permeability of the PU polymer was estimated based on effective diffusivity in foams and foam morphology and found to decrease with increasing crosslink density, apparently due to reduction in the fractional free volume in the polymers.

A comprehensive research of low-density bio-based rigid polyurethane foams from sugar beet pulp-based biopolyol: From closed-cell towards open-cell structure

The effective using of industrial agricultural crop residues in the polymer industry is still challenging. Herein, sugar beet pulp-based polyol (SBpol) was synthesized using an acid-catalyzed solvothermal liquefaction method, and then a series of bio-based rigid polyurethane foams (sPUFs) was produced using one-shot and free-rising technique by replacing up to 100 php of the petroleum-based polyol with biopolyol. The effects of an increasing amount of SBpol on the morphological, physico-mechanical, thermal, and flame retardant properties of sPUFs were evaluated. SEM pictures revealed that the cell windows of sPUFs opened as the amount of biopolyol increased, and in parallel with these results, the decreases in the closed-cell contents were determined. While the insulation properties of sPUFs containing up to 40 php biopolyol are superior, the mechanical properties of sPUFs containing 20 php biopolyol are higher than that of reference petroleum-based foam. The water absorption ratio of sPUF100 was almost 5 times higher than that of the reference foam at the end of 76 h due to the high porosity. A 6-week abiotic hydrolysis test showed that the sPUF100 sample started a partial degradation. Thermogravimetric analysis indicated that all the sPUFs were thermally stable at temperatures up to 247 °C. The flame retardant properties of sPUFs were not satisfactory because the addition of biopolyol increased both heat release rate and total smoke production; therefore, the flame resistance of sPUFs has to be increased by the incorporation of flame retardant chemicals. This study proves a useful, promising, and sustainable strategy for the development of sugar beet pulp-based polyurethane foams in the polyurethane industry.

Bio-Based Polyurethane Foams from Kraft Lignin with Improved Fire Resistance

Rigid polyurethane foams (RPUFs) were synthesized using exclusively lignin-based polyol (LBP) obtained via the oxyalkylation of kraft lignin with propylene carbonate (PC). Using the design of experiments methodology combined with statistical analysis, the formulations were optimized to obtain a bio-based RPUF with low thermal conductivity and low apparent density to be used as a lightweight insulating material. The thermo-mechanical properties of the ensuing foams were compared with those of a commercial RPUF and a RPUF (RPUF-conv) produced using a conventional polyol. The bio-based RPUF obtained using the optimized formulation exhibited low thermal conductivity (0.0289 W/m·K), low density (33.2 kg/m3), and reasonable cell morphology. Although the bio-based RPUF has slightly lower thermo-oxidative stability and mechanical properties than RPUF-conv, it is still suitable for thermal insulation applications. In addition, the fire resistance of this bio-based foam has been improved, with its average heat release rate (HRR) reduced by 18.5% and its burn time extended by 25% compared to RPUF-conv. Overall, this bio-based RPUF has shown potential to replace petroleum-based RPUF as an insulating material. This is the first report regarding the use of 100% unpurified LBP obtained via the oxyalkylation of LignoBoost kraft lignin in the production of RPUFs.

Effective Removal of Phenol from Polluted Water Via Bio-Based Rigid Polyurethane Foams in Collaboration with Alcaligenes Faecalis

Effective Removal of Phenol from Polluted Water Via Bio-Based Rigid Polyurethane Foams in Collaboration with Alcaligenes Faecalis

Bio-Based Rigid Polyurethane Foams Modified with C-MOF/MWCNTs and TBPBP as Building Insulation Materials: Synergistic Effect and Corresponding Mechanism for Enhancing Fire and Smoke Safety.

Rigid polyurethane foams (RPUFs) as building insulation materials quickly burn and release a lot of heat, smoke, and carbon monoxide, and cause human safety risk and severe environmental pollution. To mitigate these disadvantages, MOF/MWCNTs were fabricated via mixing Cu ions’ partly substituted framework of ZIF-67 and MWCNTs, and further calcinated MOF/MWCNTs (C-MOF/MWCTs) was newly generated by calcinating MOF/MWCNTs in air. Then, MOF/MWCNTs and C-MOF/MWCNTs were respectively employed together with a phosphorus–nitrogen-containing reactive flame retardant (TBPBP) to prepare renewable bio-based rigid polyurethane foam, including RPUF-T/MOF/MWCNTs 2 and RPUF-T/C-MOF/MWCNTs 2. The characterization results showed that RPUF-T/C-MOF/MWCNTs 2 had better performance than RPUF-T/MOF/MWCNTs 2 and neat RPUF. Compared to neat RPUF, the compressive strength, limiting oxygen index value, and the mass char residue in cone calorimetry test of RPUF-T/C-MOF/MWCNTs 2, respectively, were increased by 105.93%, 46.35%, and 347.32%; meanwhile, the total heat release rate, total smoke production, total carbon monoxide product, and total carbon dioxide product were reduced by 47.97%, 50.46%, 41.38%, 43.37%, respectively. This study provides a referable method for preparing RPUFs with good physical properties, fire, and smoke safety, which is favorable for human safety and environmental protection as new building insulation materials.

Anisotropic thermal expansion of bio-based rigid low-density closed-cell polyurethane foams

Rigid low-density polyurethane (PU) foams containing bio-based components are being increasingly considered as a sustainable substitute for petrochemical resources-based foams for thermal insulation in ambient conditions. However, for applications involving high temperature gradients, the thermal expansivity of foams also has to be characterised. With this aim, rigid low-density polyurethane foams have been manufactured using polyols derived from renewable resources (tall oil fatty acids) and their thermal expansion in the temperature range from 20 to −150 °C was studied. The mean coefficients of linear thermal expansion (CTE) in this range and the differential CTEs at 20 and -150 °C were determined. Increasing the cross-link density of the PU polymer matrix resulted in reduction of the CTEs of both monolithic polymer and closed-cell PU foams. Changing the molecular weight per branching unit of PU from 442 to 318 g/mol caused reduction of the differential CTE of the monolithic PU by about 30% at 20 °C and by 11% at −150 °C. The CTEs of anisotropic foams were expressed in terms of CTE of the polymer and mechanical characteristics of the foams. The predicted CTEs were found to be in good agreement with experimental ones within the temperature range considered.

Bio-Based Rigid Polyurethane Foam Composites Reinforced with Bleached Curauá Fiber.

This study aims to evaluate the influence of using a bleached Curauá fiber (CF) as filler in a novel rigid polyurethane foam (RPUF) composite. The influence of 0.1, 0.5 and 1 wt.% of the reinforcements on the processing characteristics, cellular structure, mechanical, dynamic-mechanical, thermal, and flame behaviors were assessed and discussed for RPUF freely expanded. The results showed that the use of 0.5 wt.% of CF resulted in RPUF with smoother cell structure with low differences on the processing times and viscosity for the filled pre-polyol. These morphological features were responsible for the gains in mechanical properties, in both parallel and perpendicular rise directions, and better viscoelastic characteristics. Despite the gains, higher thermal conductivity and lower flammability were reported for the developed RPUF composites, related to the high content of cellulose and hemicellulose on the bleached CF chemical composition. This work shows the possibility of using a Brazilian vegetable fiber, with low exploration for the manufacturing of composite materials with improved properties. The developed RPUF presents high applicability as enhanced cores for the manufacturing of structural sandwich panels, mainly used in civil, aircraft, and marine industries.

Evaluation of the Performance of Bio-Based Rigid Polyurethane Foam with High Amounts of Sunflower Press Cake Particles.

In the current study, rigid polyurethane foam (PUR) was modified with 10–30 wt.% sunflower press cake (SFP) filler, and its effect on performance characteristics—i.e., rheology, characteristic foaming times, apparent density, thermal conductivity, compressive strength parallel and perpendicular to the foaming directions, tensile strength, and short-term water absorption by partial immersion—was evaluated. Microstructural and statistical analyses were implemented as well. During the study, it was determined that 10–20 wt.% SFP filler showed the greatest positive impact. For instance, the thermal conductivity value improved by 9% and 17%, respectively, while mechanical performance, i.e., compressive strength, increased by 11% and 28% in the perpendicular direction and by 43% and 67% in the parallel direction. Moreover, tensile strength showed 49% and 61% increments, respectively, at 10 wt.% and 20 wt.% SFP filler. Most importantly, SFP filler-modified PUR foams were characterised by two times lower water absorption values and improved microstructures with a reduced average cell size and increased content in closed cells.

Vacuum-Based Impregnation of Liquid Glass into Sunflower Press Cake Particles and Their Use in Bio-Based Rigid Polyurethane Foam.

The study analyses rigid polyurethane (PUR) foam modified with 10–30 wt.% sunflower press cake (SFP) and liquid glass-impregnated sunflower press cake (LG-SFP) particles and their impact on performance characteristics of PUR foams—foaming behaviour, rheology, thermal conductivity, compressive strength parallel and perpendicular to the foaming directions, tensile strength, dimensional stability, short-term water absorption by partial immersion, and thermal stability. Even though the dynamic viscosity and apparent density were increased for SFP and LG-SFP formulations, thermal conductivity values improved by 17% and 10%, respectively, when 30 wt.% of particles were incorporated. The addition of SFP and LG-SFP particles resulted in the formation of more structurally and dimensionally stable PUR foams with a smaller average cell size and a greater content of closed cells. At 30 wt.% of SFP and LG-SFP particles, compressive strength increased by 114% and 46% in the perpendicular direction, respectively, and by 71% and 67% in the parallel direction, respectively, while tensile strength showed an 89% and 85% higher performance at 30 wt.% SFP and LG-SFP particles loading. Furthermore, short-term water absorption for all SFP and LG-SFP modified PUR foam formulations was almost two times lower compared to the control foam. SFP particles reduced the thermal stability of modified PUR foams, but LG-SFP particles shifted the thermal decomposition temperatures towards higher ones.

Enhancing the Fire Safety and Smoke Safety of Bio-Based Rigid Polyurethane Foam via Inserting a Reactive Flame Retardant Containing P@N and Blending Silica Aerogel Powder.

Rigid polyurethane foams (RPUFs) are widely used in many fields, but they are easy to burn and produce a lot of smoke, which seriously endangers the safety of people’s lives and property. In this study, tetraethyl(1,5–bis(bis(2–hydroxypropyl)amino)pentane–1,5–diyl)bis(phosphonate) (TBPBP), as a phosphorus–nitrogen–containing reactive–type flame retardant, was successfully synthesized and employed to enhance the flame retardancy of RPUFs, and silica aerogel (SA) powder was utilized to reduce harmful fumes. Castor oil–based rigid polyurethane foam containing SA powder and TBPBP was named RPUF–T45@SA20. Compared with neat RPUF, the obtained RPUF–T45@SA20 greatly improved with the compressive strength properties and the LOI value increased by 93.64% and 44.27%, respectively, and reached the V–0 rank of UL–94 testing. The total heat release (THR) and total smoke production (TSP) of RPUF–T45@SA20 were, respectively, reduced by 44.66% and 51.89% compared to those of the neat RPUF. A possible flame–retardant mechanism of RPUF–T45@SA20 was also proposed. This study suggested that RPUF incorporated with TBPBP and SA powder is a prosperous potential composite for fire and smoke safety as a building insulation material.