Smoke Suppression Properties Research Articles

Preparation of phosphorus-containing organic-hybrid layered double hydroxide as a flame retardant for thermoplastic polyurethane

Developing polymers with both flame-retardant and smoke-suppressing properties is a great challenge in the field of fire-safety thermoplastic polyurethane (TPU). This study involved synthesizing a synergistic organic-hybrid layered double hydroxide (O-LDH) and phosphorus/nitrogen-containing substance (PD) inspired by the observed synergistic effect between them. The incorporation of PD significantly enhanced the flame-retardant properties of TPU in conjunction with cobalt/aluminum- layered double hydroxide. The composite containing 10 wt% O-LDH achieved a limiting oxygen index of 26.5% and met the vertical burning V-0 rating. Moreover, the heat and smoke release were decreased compared to pure TPU in cone calorimeter tests. The systematic characterization of the synergistic flame-retardant mechanism emphasized the crucial contribution of cobalt and phosphorus species in catalyzing charring effects, resulting in the compact and highly carbonized char layer in the condensed phase. The incorporation of the hybrid flame retardant significantly enhanced the advancement of the flame-retardant TPU materials.

Smoke Suppression Properties of Fe2O3 on Intumescent Fire-Retardant Coatings of Styrene–Acrylic Emulsion

The intumescent flame-retardant coatings were prepared using ammonium polyphosphate (APP), pentaerythritol (PER), melamine (MEL), styrene–acrylic emulsion, and iron oxide yellow (FeOOH) as the base material. A cone calorimeter (CCT), smoke density meter (SDA), and scanning electron microscope (SEM) were employed to investigate the smoke suppression and flame retardancy of FeOOH in intumescent fire-retardant coatings. The thermal degradation performance of intumescent fireproofing coatings with varying FeOOH content was investigated through thermogravimetric analysis (TGA). The structure of the carbon slag in the CCT test was analyzed using a scanning electron microscope (SEM). The results of the cone calorimeter (CCT) experiments demonstrated that FeOOH significantly reduced the heat release rate (HRR), total heat release rate (THR), smoke production rate (SPR), and total smoke release rate (TSR) of the coating, while simultaneously increasing the carbon residue rate of the coating. The smoke density analysis (SDA) results demonstrate that adding FeOOH can effectively reduce smoke generation, regardless of whether a pilot flame is used. TGA results demonstrate that FeOOH can enhance the weight of coke residue at elevated temperatures. SEM results indicate that incorporating FeOOH resulted in a more compact coke residue. According to these findings, among all the samples, those containing 2 wt% FeOOH showed low levels of HRR, THR, SPR, and TSR and high levels of SOD, which proves that FeOOH can be used as a smoke inhibitor in flame-retardant coatings.

The impact of DOPO‐derived phosphoramides containing triazine moieties on the flame retardancy and smoke suppression properties of waterborne polyurethane

AbstractWaterborne polyurethane (WPU), which is a novel and environmentally friendly variety of polyurethane, replaces organic solvents with water. It has been extensively utilized in diverse fields encompassing coatings, textile finishing, building decoration, adhesives, plastic chemistry, and others. However, WPU is inherently flammable and releases a significant amount of smoke production during the combustion process. This research presents an original fire‐resistant Waterborne Polyurethane (WPU) with a newly‐integrated flame‐retardant component comprising a triazine phosphoramidate segment derived from 9,10‐dihydro‐9‐oxo‐10‐phosphaphenanthrene‐10‐oxide (DOPO) within its primary structure. In comparison to pure WPU, the limiting oxygen index (LOI) of flame‐retardant WPU (FRWPU) increased from 19.6% to 29.2%. In UL‐94 testing, the FRWPU film achieved a V‐0 rating with only 6% retarding component. Additionally, in cone calorimetry tests, Total Heat Release (THR), peak Heat Release Rate (pHRR), Total Smoke Production (TSP), Smoke Production Rate (SPR), and peak Carbon Monoxide Production Rate (pCOP) are decreased by 27.7%, 16.2%, 64.6%, 61.3%, and 77.8%, respectively. The greater degree of graphitization observed in the residual carbon substantially impeded heat exchange and the emission of smoke during combustion. Flame‐retardant intermediate segments greatly improved the FRWPUs' ability to suppress smoke and remain flame‐retardant. The creation and formulation of aqueous polyurethanes that are flame‐retardant can benefit greatly from the insights and references offered by this research.

Modification with lignin-based N-P flame retardant to improve the flame retardancy and smoke suppression of wood

The development of effective and eco-friendly wood-based functional composites is crucial for maximizing the value of forest resources. In this paper, we propose a novel method for preparing an aqueous-phase flame retardant (MPUC) using carboxymethylation alkali lignin, phytic acid, and melamine-urea-glyoxal resin. This approach aims to manufacture modified wood (MW/MPUC) with exceptional flame-retardant and smoke-suppressing properties. The results from the cone calorimeter test indicate that the modified wood achieved a remarkable reduction of up to 56.8 % in total heat release and an impressive 92.3 % decrease in total smoke production. Furthermore, the limiting oxygen index increased significantly from 23.6 % (natural wood) to 41.5 % (MW/MPUC-2). Notably, all modified wood successfully passed the V-1 test for UL-94 flammability rating. Further, our investigation into the gas-phase products formed during pyrolysis and the condensed-phase system created after combustion has led us to propose potential flame-retardant mechanisms for these flame retardants. Moreover, modified wood had improved mechanical properties and dimensional stability than natural wood. In addition, we extended the application of MPUC-2 flame-retardant to other flammable materials and demonstrated its excellent flame-retardant properties. Thus, the proposed strategy provided a new approach for preparing wood-based flame-retardant composites with lignin-based N-P flame retardants.

Facile-controllable synthesis of 3D cross-shaped ZIF-67 to achieve highly efficient flame retardancy and smoke suppression for TPU composites

Zeolite imidazolium frameworks (ZIFs), as a subcategory of metal-organic frameworks (MOFs), are widely used in many fields. And, the physical morphology, particle size, and shape of ZIFs have an important influence on their application performance, such as flame retardancy for polymer. Here, three types of ZIF-67 were prepared with different physical morphology structures including dodecahedron (ZIF-67), cube (ZIF-67 NC), and cross-shaped (ZIF-67 H), by adjusting the proportion between 2-methylimidazole and cobalt (Ⅱ) nitrate hexahydrate together with the suitable amount of surfactant (CTAB), and they were used to enhance the flame retardancy and smoke suppressing properties of thermoplastic polyurethane (TPU). It has been found the novel ZIF-67 H with 3D cross-shaped superior catalytic and flame-retardant capabilities than the other two during the burning process of TPU composites. Compared with those of pure TPU, the peak heat release rate (pHRR), total smoke production (TSP), and smoke factor (SF) of TPU/2 wt%ZIF-67 H were decreased by 45.4 %, 50.2 %, and 72.9 %, respectively. At the same time, both TPU/1 wt%ZIF-67 H and TPU/2 wt%ZIF-67 H samples showed stronger tensile properties than pure TPU at the same elongation. This work further enriches the study of multi-structured ZIFs for flame retardant TPU.

Ultrafine Fe(OH)3 nanoparticles formation via oxidation-mediated strategies towards remarkable flame-retardant and smoke-suppressant performances

Transition metal nanomaterials are widely applied as flame retardants in materials. Herein, an oxidation-mediated strategy was developed for temporally controlling the in situ growth of Fe(OH)3 nanoparticles on wool/nylon (W/N) fabrics. The formed particles exhibit homogeneous dispersion on the surface of W/N fabrics, with an average particle diameter of about 60 nm. These Fe(OH)3 nanoparticles can simultaneously enhance both the flame retardancy (the limiting oxygen index increased by 18.8 % and passed the UL-94 burning test of V-0 rating) and mechanical performance (the tensile strength increased by 9.13 %) of the W/N fabrics. Meanwhile, the obtained W/N fabrics exhibit remarkable smoke-suppressant properties, demonstrating a reduction of 76.4 % and 65.5 % in smoke production rate and total smoke production, respectively, compared to the pure W/N fabrics. Furthermore, the prepared W/N fabrics exhibit good durability. This innovative strategy may be also extended for synthesizing other nanomaterials and pave a new path to develop high-performance flame-retardant materials.

In situ growth of Ag nanoparticles on the surface of MXene by γ-ray irradiation to fabricate EVA composite: the improvement of flame retardancy, smoke suppression, and mechanical properties

A large amount of toxic smoke and heat generated by the combustion of ethylene vinyl acetate copolymer (EVA) poses a significant threat to human fire escape evacuation. This work aims to use γ-ray to prepare e-MXene@Ag hybrid flame-retardant materials by the method of in-situ reduction, and EVA composites are prepared by melt blending to reduce the smoke and toxic gases produced during combustion significantly. Compared with pure EVA, the total heat release, total smoke release, and the production rate of CO and CO2 produced by the combustion of EVA composite with 1 wt% e-MXene@Ag1.0 decreased by 30.3%, 33.3%, 18.2%, and 20.1% respectively. The fire hazard reduction of EVA composite materials was due to the physical barrier, catalytic carbonization and adsorption of the e-MXene@Ag1.0 hybrid. In addition, e-MXene@Ag1.0 can also further increase the mechanical properties of EVA composites due to its own ‘multi-contact point limit structure’.

Exploiting Waste towards More Sustainable Flame-Retardant Solutions for Polymers: A Review.

The development of sustainable flame retardants is gaining momentum due to their enhanced safety attributes and environmental compatibility. One effective strategy is to use waste materials as a primary source of chemical components, which can help mitigate environmental issues associated with traditional flame retardants. This paper reviews recent research in flame retardancy for waste flame retardants, categorizing them based on waste types like industrial, food, and plant waste. The paper focuses on recent advancements in this area, focusing on their impact on the thermal stability, flame retardancy, smoke suppression, and mechanical properties of polymeric materials. The study also provides a summary of functionalization methodologies used and key factors involved in modifying polymer systems. Finally, their major challenges and prospects for the future are identified.

Self-assembly Fe-Co MOF@BN and epoxy resin nano composites with highly enhanced flame retardancy and smoke suppression properties

A shuttle-shaped Fe-Co bimetallic metal organic frameworks (MOFs) on sheet-like hexagonal boron nitride (h-BN) was fabricated via an organic-inorganic hybrid strategy, forming a novel Fe-Co MOF@BN flame retardant, and the hybrids together with ammonium polyphosphate (APP) were incorporated into epoxy resins to explore their flame retardancy and smoke suppression effects. When combining 0.5 % Fe-Co MOF@BN with 9.5 % APP, the peak heat release rate, peak smoke release rate, CO production rate, and peak CO2 production rate of the EP composite (EP/APP/Fe-Co MOF@BN) were reduced by 73.7 %, 71.4 %, 70 %, and 80 % respectively, compared to epoxy. The limiting oxygen index increases to 30.2 %, indicating the EP/APP/Fe-Co MOF@BN composites have superior fire safety performance. The excellent fire performance of EP/APP/Fe-Co MOF@BN composites benefiting from the barrier effect of Fe-Co MOF@BN lamellar structure, the catalytic carbonization of Fe and Co, the gas phase dilution of APP and the enhancement of the cross-linking degree of the char layer. Meanwhile, Fe-Co MOF@BN improves the dispersion of APP in the EP composites, which broadens the application range of MOF and h-BN. Herein, the EP/APP/Fe-CoMOF@BN composites with high flame retardancy, low smoke production rate, and excellent mechanical properties provide a feasible solution for the use of EP under high temperatures.

Research on the synergistic flame retardation of epoxy resin through surface-modified aluminum diethylphosphinate in conjunction with DOPO and CFA

Surface modification of aluminum diethylphosphinate (ADP) was successfully achieved through the utilization of silane coupling agent KH-560. Simultaneously, the modified aluminum diethylphosphinate (K-ADP) served as the primary flame retardant, with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as the phosphorus-based flame retardant and charring‐forming agent (CFA) as the nitrogen-based synergistic flame retardant. This approach was employed to investigate the flame-retardant modification of epoxy resin. The optimal dosage of the surface modifier was investigated through moisture absorption test and viscosity measurements. Synergistic flame-retardant interactions among K-ADP, DOPO, and CFA were examined using techniques such as cone calorimetry test, thermogravimetric analysis, and residual char infrared analysis. The results indicated that the optimal dosage of KH-560 is 5%, resulting in a significant reduction in moisture absorption to 0.195%. At 80 °C, the addition of K-ADP leaded to only a 22.7% increase in system viscosity, demonstrating a notable viscosity reduction effect. When the addition of K-ADP is 14%, the Limiting Oxygen Index (LOI) value reached 30.5%, achieving a V-0 rating. Moreover, by maintaining the total addition at 14% and introducing DOPO and CFA, it is evident that most of samples meet UL-94 V-0 rating, with the LOI elevated to 32.2%. CCT results indicated a significant decrease in both average heat release rate and total smoke production, reduced by 24.1% and 7.0%, respectively. This notably enhanced the flame-retardant and smoke-suppressant properties of the EP composite material. The addition of K-ADP, DOPO, and CFA improved the mechanical performance of the EP composite material, surpassing the effectiveness of adding ADP individually.

Cyano group‐containing DOPO derivative for improving the flame retardancy, smoke suppression, and mechanical properties of epoxy resins

AbstractIn order to obtain an efficient flame retardant and smoke suppressor without sacrificing mechanical properties of epoxy resin (EP). A cyano group‐containing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) derivative (CP‐DOPO) was proposed and synthesized through one‐step Atherton–Todd reaction between DOPO and 4‐cyanophenol. The comprehensive performance analysis of CP‐DOPO‐based EP composite was conducted by measuring the flame retardancy, smoke suppression, and mechanical properties. The flame‐retardant test findings shows that the EP/4CP‐DOPO sample achieves UL‐94 V‐0 rating with 4 wt% low addition of CP‐DOPO. Moreover, EP/6CP‐DOPO sample presents a LOI of 36.5%, a 28.1% reduction in the peak heat release rate, and a 42.1% substantial decrease in total smoke production, demonstrating its desirable flame retardancy and smoke suppression properties. Significantly, different from the traditionally additive flame retardants, the mechanical properties of EP matrix will not be affected by the incorporation of CP‐DOPO but a 17.7% increasement of flexural properties compared to EP. This research not only provides an ingenious strategy for designing and preparing high‐effective flame retardant but also enhances the comprehensive performance of EP resins in practical applications.

Construction of functional epoxy resin coatings based on acid-doping polyaniline coated APP: Preparation, characterization and properties

Waterborne epoxy resin (WER) coatings have attracted more and more attention because of their excellent physical and chemical properties, however, WER's flammability and high insulation limit its application. In this paper, polyaniline (PANI) doped with four different acids (sulfuric acid, phosphoric acid, citric acid and amino trimethylene phosphonic acid) was used as the shell material to coat ammonium polyphosphate (APP), and a series of multifunctional WER fillers (PANIacids/APP) integrating flame retardant, smoke suppression and antistatic properties were prepared. Then, the PANIacids/APP was compounded with WER to prepare a functional WER coating. The structures and morphologies of the PANIacids/APP fillers were characterized by Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), the results showed that acids doping could promote the formation of polyaniline coating on the surface of APP, and the PANIacids/APP filler doped by amino trimethylene phosphonic acid (ATMP) exhibits the best coating effect. Furthermore, the effects of PANIacids/APP fillers on the flame retardant property, smoke suppression property, electrical property and adhesion property of waterborne epoxy resins were explored. The results indicated that the carbon residue of WER coatings with PANIacids/APP fillers at 800 °C could reach 24.1 %-29.6 %, among which ATMP doping group has a residual carbon of 27.3 %. Also, the WER coating containing PANIATMP/APP filler possesses the best comprehensive performance, the coating has a limiting oxygen index of 31.7 % and passed V-0 level in the vertical burning test (UL-94). Compared with pure EP coating, the peak heat release rate of the PANIATMP/APP modified coating decreased by 78.1 % and the total heat release decreased by 37.8 %. Additionally, the surface resistance and adhesive force of the PANIATMP/APP modified coating reached 3.14×106 Ω and 11.8 MPa, respectively, which could meet the usage needs of anti-static application of the WER coatings.

Synthesis of CoMn‐LDH@MXene Hybrid Materials as Flame Retardant to Effectively Improve the Fire Safety of Thermoplastic Polyurethane

AbstractIn recent years, MXene 2D materials have shown good performance in enhancing the flame retardant properties of composite materials, but it is still tricky to improve the compatibility with the polymer matrix. This work explores a simple method for the synthesis of MXene based nanohybrids (CoMn‐LDH@MXene) by hydrothermal synthesis using MXene and layered double hydroxides (CoMn‐LDH) to construct a flame retardant system with excellent performance. The results show that the MXene nanosheets are less built up and more dispersed in the TPU collective due to the inclusion of LDH, giving the TPU composites excellent flame retardant and smoke suppressant properties. Compared to TPU without flame retardant, TPU composites with 2 wt% CoMn‐LDH@MXene reduced PHRR by 33.7 % and THR by 28.7 %. The TPU/2wt %CoMn‐LDH@MXene composites also showed better flame and smoke suppression performance, PSPR, TSP, PCO and PCO2 were reduced by 44.4 %, 22.7 %, 37.7 % and 27.2 % respectively, the production of Hydrocarbons and HCN were also reduced. Barrier effect of transition metal oxide catalysed carbon layer formation, combustion blocking effect of hybrid material nanosheets, cooling effect of water vapour from thermal decomposition of LDH and the gas phase dilution effect are the main reasons for the increased fire safety of TPU composites.

Preparation of flame retardant and antibacterial polyacrylonitrile based on Cu2+ chelated six-armed star-type flame retardant SCCP and chitosan

In this work, a six-armed star-type flame retardant (SCCP) contained phosphorus, nitrogen and sulfur contents was developed, which was then combined with chitosan (CS) to chelate Cu2+ (SCCP@CS-Cu) and blend with polyacrylonitrile (PAN) to produce flame retardant and antibacterial PAN composite (PAN/SCCP@CS-Cu). TG showed that the residual char of PAN/SCCP@CS-Cu in air and nitrogen atmosphere was as high as 16.41 % and 48.48 % at 800 °C, respectively, which were greater than that of PAN. The LOI value of PAN/SCCP@CS-Cu improved to 33.0 % and the peak heat release rate (PHRR) and total heat release (THR) of the composite were all greatly reduced. In addition, the total smoke production (TSP) of PAN/SCCP@CS-Cu decreased by 73.6 % compared to the control sample. Interestingly, the antibacterial properties of PAN/SCCP@CS-Cu against E. coli and S. aureus reached 98.45 % and 99.33 %. This work provides an insight into developing an environmentally friendly PAN composite with flame retardancy, smoke suppression and antibacterial properties, greatly expanding its application field.

Construction of a hybrid flame retardant based on mesoporous silica for enhancing fire safety, smoke suppression, and mechanical properties of epoxy resins

AbstractIn order to improve the fire safety of epoxy resins (EPs), the SBA‐15 based hybrid flame retardant (SNAZD) was synthesized via an organic–inorganic hybridization strategy of mesoporous silica SBA‐15. Relying on electrostatic interaction, the zinc amino‐tris‐(methylenephosphonate) (Zn‐ATMP) was successfully introduced into the pore channels of SBA‐15. Then, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) was successfully loaded into the pores of SBA‐15 under vacuum. The results show that the EP composites with the 5%SNAZD sample (sample EP‐5%SNAZD) showed a LOI value of 30.9% and achieved the vertical burning V‐0 rating. In comparison to EP, the peak heat release rate, peak smoke production rate, and production rate of CO of EP‐3%SNAZD were reduced by 32.2%, 31.9%, and 20.0%, respectively. This is due to the presence of Si, P, N, and Zn elements in the SNAZD, which promoted the generation of a high yield of dense char residue and inhibited the release of toxic gasses. And the impact strength and flexural strength of EP‐1%SNAZD were increased by 19.5% and 15.6%, respectively, and the E' of EP‐5%SNAZD increased by 49.1% when compared with the neat EP. This work provides a general strategy for the design of mesoporous hybrid flame retardant and creates additional opportunities for applications of EP.

Mechanical and Fire Properties of Flame-Retardant Laminated Bamboo Lumber Glued with Phenol Formaldehyde and Melamine Urea Formaldehyde Adhesives.

This study investigated the effects of different adhesives, phenol formaldehyde (PF) and melamine urea formaldehyde (MUF), on the mechanical and fire properties of flame-retardant laminated bamboo lumber (LBL). The results demonstrated that the flame-retardant treatment using phosphorus-nitrogen-boron compounds endowed the LBL with excellent flame retardancy and smoke suppression properties, even though the bending strength and bond shear strength were slightly reduced. The PF-glued LBL exhibited superior mechanical and shear properties to the MUF-glued ones, primarily due to its higher processing temperature and deeper adhesive penetration. In addition, the MUF-glued flame-retardant LBL displayed better heat release reduction and smoke suppression properties than the PF-glued LBL, which resulted from the synergistic flame retardancy between the melamine element in MUF and the applied flame retardant. The analysis of the influence of adhesive type on the mechanical and fire properties of flame-retardant LBL holds significant importance for the future design and production of high-performance LBL material.

Green vanillin coupled with P/N/Si flame retardant for poly (L-lactic acid)

To better solve the flammability of poly (l-lactic acid) (PLLA) and meet environmental concerns, developing bio-derived flame retardants for PLLA is an alternative method. A green flame retardant (VKD) was synthesized in the work. Vanillin was modified using 3-amino-propyl-triethoxysilane (KH550) prior to coupling with 9, 10-dihydro-9-oxa-10-phosphafi-10-oxide (DOPO). As the blend ratio of VKD to PLLA was 20 wt%, the limiting oxygen index (LOI) and UL-94 were 25.5% and V-0 rating, respectively; and the residual carbon rate reached 9.14% at 600 °C, which was 3.3 times higher than that of PLLA. In the cone calorimetry test, the peak heat release rate (pHRR) and total heat released (THR) reduced by 9.9% and 20.5%, respectively, and total smoke production (TSP) decreased by 26.8%, indicating that VKD/PLLA had good flame retardancy and smoke suppression properties. It was mainly attributed to initial condensation phase obstacle and following combination of gaseous phase quenching and carbon/silicon composite barrier. The VKD/PLLA maintained balanceable mechanical properties and good degradation. Then green VKD would broaden PLLA in the application of engineering such as electronic products and automotive interior materials.

Flame-retardant thermoelectric responsive coating based on poly(3,4-ethylenedioxythiphene) modified metal–organic frameworks

Abstract Poly(3,4-ethylenedioxythiophene) (PEDOT) is introduced on the surface of a metal–organic framework material by solvothermal method to prepare nanorods (TE@Zn-MOFs) with both flame retardant and thermoelectric properties. Data from cone calorimeter and TG-IR show that TE@Zn-MOFs effectively improves the flame retardant and smoke suppression properties of epoxy-based coatings. At a high TE@Zn-MOFs content of 10 wt%, the coating oxygen index increased from 18.2% to 29.0%, the total smoke release decreased from 25.26 to 22.60 m2, and the V-0 level was achieved in vertical combustion classification. Moreover, PEDOT enables epoxy-based coatings to output a certain current value at different heating temperatures (50–200°C). This work demonstrates that MOFs with flexible and variable structures can serve as effective flame retardants for epoxy-based coatings and endow coatings with fire warning characteristics, providing a way to develop multifunctional coatings for different application scenarios.

A novel phosphorus/nitrogen-containing polyacrylonitrile fiber with excellent flame retardancy and mechanical properties

To improve the flame retardancy, smoke suppression and mechanical properties of polyacrylonitrile (PAN) fiber, it was first modified with diethylenetriamine to prepare the aminated PAN fiber (A-PAN). Second, diethyl phosphite (DEP) was grafted onto the A-PAN to fabricate flame retardant PAN fiber (DEP-A-PAN). XPS and FTIR analysis confirmed that phosphorus and nitrogen elements were covalently bonded to the surface of PAN fiber. TGA revealed that the incorporation of DEP promoted char formation of PAN matrix and suppressed the thermal degradation. DEP-A-PAN exhibited a significantly reduced peak heat release rate (pHRR) compared to the control sample. Moreover, the limiting oxygen index (LOI) of DEP-A-PAN was up to 34.3 %, and remained at 26.6 % even after 50 laundering cycles (LCs), demonstrating excellent durable flame retardancy. Interestingly, DEP-A-PAN exhibited improved tensile strength of 2.97 cN/dtex. This work developed a simple and feasible method for preparing mechanical-enhanced flame retardant and smoke suppressive PAN fiber, which could be large-scale preparation.

A novel phosphorus-modified silica aerogel for simultaneously improvement of flame retardancy, mechanical and thermal insulation properties in rigid polyurethane foam

Due to the wide application of rigid polyurethane foam (RPUF) in the fields of building structural materials and thermal insulation materials, the development of high-performance RPUF composites with exceptional flame retardancy, smoke suppression, and mechanical properties is of paramount importance. In this study, we present an approach involving the amalgamation of a phosphorus-containing diol with ammonium polyphosphate to fabricate phosphorus-hybridized silica aerogel (P-SiA). The unique dual hydroxyl configuration of DDP exhibits a remarkable reactivity with silica sol, thereby facilitating the effective dispersion of APP within the silica sol. Additionally, the polyhydroxyl structure within the P-SiA enhance its compatibility with the RPUF. The compressive strength of RPUF/P-SiA-5 increased by approximately 46.4% in comparison to pristine RPUF. Furthermore, in contrast to pristine RPUF, the thermal insulation effect of RPUF/P-SiA composites were further enhanced. In addition, the effective integration of two distinct phosphorus-containing compounds in P-SiA effectively enhances the flame retardancy of RPUF composites, as substantiated by the achievement of a limiting oxygen index value of 23.2% for RPUF/P-SiA-15. Besides, relative to RPUF containing pure silica aerogel, both heat release and smoke release of RPUF/P-SiA composites are effectively suppressed. The implications of these findings propose a new strategy of tailoring material interactions and optimizing composite formulations to obtain the high-performance RPUF composites, which has a broad application prospect.