Limiting Oxygen Index Research Articles

Construction of epoxy resin with enhanced flame retardancy, mechanical properties, and satisfactory transparency based on a novel bi‐DOPO and hydrogen‐bonding network

AbstractEstablishment of high‐performance epoxy resin with satisfactory fire safety, mechanical properties, and excellent transparency is urgently desirable, but still remains significant challenges. Herein, a super‐tough yet high flame retardant epoxy resin (EP/BTD) was designed and prepared by incorporating bi‐DOPO structure and hydrogen‐bonding networks. Although the phosphorus content was only 0.69 wt% (10 wt% of bi‐DOPO flame retardant [BTD]), EP/BTD‐10 showed a high limiting oxygen index value (33.4%), satisfactory UL‐94 rating (V‐0), and good heat suppression ability (total heat release [THR] and peak heat release rate [PHRR] reduced to 29.0% and 42.2%, respectively). Furthermore, the flame retardant mechanism of EP/BTD was illustrated and attributed to dual‐phase fire‐retardant effect. Additionally, EP/BTD‐7.5 featured notably mechanical properties, of which the tensile strength, elongation at break and impact strength increased by 44.6%, 40.0%, and 232.6%, respectively, due to hydrogen‐bonding network and π–π interaction. More importantly, EP/BTD maintained high visible light transmittance and excellent UV‐blocking properties. In summary, this work provided a guidance for the development of high‐performance epoxy resin and was expected to expand the practical applications.

High rubber elasticity and thermal conductivity in plasticized polyvinyl chloride film with flame retardancy and smoke suppression properties

AbstractFor hydrogenated nitrile‐butadiene rubber (HNBR) modified polyvinyl chloride (PVC), magnesium hydroxide and antimony trioxide are frequently employed as flame retardants. Fume silica is thought to be useful reinforced agent for rubber as well as efficient flame retardant for polymer‐based composites. The plasticized PVC and HNBR blend in this work were combined with three fillers mentioned above to create rubber‐plastic composites that performed well overall, with a notable improvement in combustion. The limiting oxygen index of the composites increased from 23.7% to 33.8% with no droplets falling during combustion, the smoke density rating decreased from 23.8% to 7.9%, and the maximum smoke density dropped from 95.5% to 15.5%. The cone calorimetry test findings revealed that the three fillers simultaneously prevented the emission of smoke and heat from combustion. High thermal conductivity is typically linked to excellent flame retardancy. The thermal conductivity of composites rose from 0.193 to 0.583 W m−1 K−1 with the addition of fillers. Furthermore, the low glass transition temperature and permanent set of improved composites reflect its softness and rubber elasticity. Thermogravimetric analysis was used to examine the thermal stability of the composites in nitrogen and air, and the results indicated the addition of fillers improved the thermal stability.

Synergistic Reinforcing Effect of Hazelnut Shells and Hydrotalcite on Properties of Rigid Polyurethane Foam Composites

Recently, the development of composite materials from agricultural and forestry waste has become an attractive area of research. The use of bio-waste is beneficial for economic and environmental reasons, adapting it to cost effectiveness and environmental sustainability. In the presented study, the possibility of using hazelnut shell (HS) and hydrotalcite (HT) mineral filler was investigated. The effects of fillers in the amount of 10 wt.% on selected properties of polyurethane composites, such as rheological properties (dynamic viscosity, processing times), mechanical properties (compressive strength, flexural strength, hardness), insulating properties (thermal conductivity), and flame-retardant properties (e.g., ignition time, limiting oxygen index, peak heat release), were investigated. Polyurethane foams containing fillers have been shown to have better performance properties compared to unmodified polyurethane foams. For example, the addition of 10 wt% of hydrotalcite filler leads to PU composite foams with improved compression strength (improvement by ~20%), higher flexural strength (increase of ~38%), and comparable thermal conductivity (0.03055 W m–1 K–1 at 20 °C). Moreover, the incorporation of organic fillers has a positive effect on the fire resistance of PU materials. For example, the results from the cone calorimeter test showed that the incorporation of 10 wt% of hydrotalcite filler significantly reduced the peak of the heat release rate (pHRR) by ca. 30% compared with that of unmodified PU foam, and increased the value of the limiting oxygen index from 19.8% to 21.7%.

Enhancing Flame Retardancy in Epoxy Resin with Clever Self-Assembly Method for Optimizing Interface Interaction via Well-Dispersed Cerium Oxide on Piperazine Pyrophosphate

Developing flame-retardant epoxy resins (EPs) is essential to broaden their industrial applications, as their inherent flammability restricts their widespread use. In this study, commercial cerium oxide (CeO2) nanoparticles were modified with oleic acid and successfully assembled onto the surface of pyrophosphate piperazine (PAPP) through a simple solvophobic effect, constructing an integrated superstructure flame retardant, CeO2@PAPP, with enhanced performance integration. Compared to traditional simple blends, the EP composite with 10 wt% CeO2@PAPP displayed superior flame retardancy, thanks to the more subtle synergistic effects between flame retardant components and their favorable interface interactions. The EP composite achieved a UL-94 V-0 rating and increased the limiting oxygen index (LOI) to 34.2%. Significant reductions of 56.3% in peak heat release rate (PHRR) and 38.2% in total heat release (THR) were observed. Furthermore, total smoke release (TSR), carbon monoxide yield (COPR), and carbon dioxide yield (CO2PR) decreased by 52.2%, 50.2%, and 67.3%, respectively. Through comprehensive and detailed characterization, it was discovered that the assembled integrated CeO2@PAPP flame retardant can perform better in both the gas phase and condensed phase, resulting in superior flame-retardant properties. This study offers an effective strategy for developing highly flame-retardant EPs, thereby expanding their potential applications across various industries.

Diphenylphosphine oxide derivative with a symmetrical structure as an efficient flame retardant for application in epoxy resin

AbstractA fresh phosphorus‐containing fireproofing agent (oxybis(4,1‐phenylene))bis((2,5‐dihydroxyphenyl)(phenyl)phosphine oxide) (ODDPO‐HQ) was synthesized by a simple two‐step reaction. The effect of ODDPO‐HQ on the glass transition temperature (Tg), crosslinking density, thermal stability, fire resistance, dielectric performances, hydrophobicity, and water absorption of epoxy resin (EP) was studied. EP/ODDPO‐HQ containing 1.2 wt% phosphorus not only achieved the vertical burning V‐0 grade with a limited oxygen index of 28.9% but also maintained good thermal stability. Compared to unmodified EP, its Tg value has only decreased by 7.2°C. Detailed studies revealed that the excellent flame resistance of ODDPO‐HQ for epoxies was ascribed to the flame suppression both in the gaseous phase and condensed phase, especially the obvious barrier effect. Although the water uptake of the modified epoxies slightly rose with the content of ODDPO‐HQ caused by the reduction of the crosslinking density within the matrix, it did not adversely affect the properties of the polymer. The modified epoxies showed reduced dielectric constant and dielectric loss values, and the contact angle of EP/ODDPO‐HQ samples increased as the flame retardant content rose, which might be due to the symmetrical structure of ODDPO‐HQ reducing the polarity. Our study presents an easy approach for producing high‐performance epoxies.

Effects of Anchovy, Mussel, and Shrimp Powders on the Flame Retardancy of Bacterial Cellulose

ABSTRACT This study aims to fabricate bacterial cellulose with improved flame retardancy by applying anchovy, mussel, and shrimp powders. The elemental analysis confirmed that raw marine powders contained nitrogen and sulfur elements which could play important roles in enhancing the flame retardancy of bacterial cellulose. Thermogravimetric analysis revealed the improved thermal stability of bacterial cellulose following entrapping and crosslinking of the marine powders. The fabricated bacterial celluloses with marine powders had similar levels of flame retardancy as that of bacterial cellulose treated with a commercial flame-retardant, sodium metasilicate nonahydrate, which was confirmed by the vertical flammability test and limiting oxygen index. The char morphology analysis revealed intumescent char on the surface of the samples, confirming the effect of marine powders on the flame retardancy of bacterial cellulose. Moreover, the marine powders were entrapped and crosslinked with bacterial cellulose nanostructures, and the chemical and crystalline structures of bacterial cellulose were retained. This study proposes an efficient method to improve the flame retardancy of bacterial cellulose by introducing marine powders via the combined entrapment and crosslinking method.

Char, gas, and action: Transfer of the flame-retardant modes of action in epoxy resins and their fiber-reinforced composites

Flame retardants are often developed for epoxy resins and then transferred into their fiber-reinforced composites with uncertain results. Understanding this transfer in detail represents a critical scientific challenge. This study systematically compares epoxy resins with their glass-fiber reinforced composites, focusing on bisphenol A diglycidyl ether with the hardener dicyandiamide, the flame retardants melamine polyphosphate, ammonium polyphosphate, and silane ammonium polyphosphate, along with inorganic silicate. The research investigates changes in pyrolysis (thermogravimetry), flammability (UL 94, limiting oxygen index), and fire behavior (cone calorimeter) while also examining the flame-retardant modes of action and overall fire performance. The findings reveal that alterations in the amount of fuel, thermal properties, melt flow, and protective layer significantly impact ignition, flammability, and fire load, with a critical reduction in carbonaceous char within the composites preventing intumescence. This study quantifies the effects and provides a fundamental scientific understanding of the complex transfer process of flame retardants from resins to composites, offering essential insights that are of major importance for developing more effective flame-retardant materials.

Preparation and Characterization of Glucose-Based Self-Blowing Non-Isocyanate Polyurethane (NIPU) Foams with Different Acid Catalysts.

The preparation and application of non-isocyanate polyurethane (NIPU) from biomass raw materials as a substitute for traditional polyurethane (PU) has recently become a research hot topic as it avoids the toxicity and moisture sensitivity of isocyanate-based PU. In the work presented here, self-blowing GNIPU non-isocyanate polyurethane (NIPU) rigid foams were prepared at room temperature, based on glucose, with acids as catalysts and glutaraldehyde as a cross-linker. The effects of different acids and glutaraldehyde addition on foam morphology and properties were investigated. The water absorption, compressive resistance, fire resistance, and limiting oxygen index (LOI) were tested to evaluate the relevant properties of the foams, and scanning electron microscopy (SEM) was used to observe the foams' cell structure. The results show that all these foams have a similar apparent density, while their 24 h water absorption is different. The foam prepared with phosphoric acid as a catalyst presented a better compressive strength compared to the other types prepared with different catalysts when above 65% compression. It also presents the best fire resistance with an LOI value of 24.3% (great than 22%), indicating that it possesses a good level of flame retardancy. Thermogravimetric analysis also showed that phosphoric acid catalysis slightly improved the GNIPU foams' thermal stability. This is mainly due to the flame-retardant effect of the phosphate ion. In addition, scanning electron microscopy (SEM) results showed that all the GNIPU foams exhibited similar open-cell morphologies with the cell pore sizes mainly distributed in the 200-250 μm range.

Co Hybrids modified piperazine pyrophosphate towards efficient flame retardancy, smoke suppression, and high mechanical properties of styrenic thermoplastic elastomer

The highly flammable nature of thermoplastic elastomers (TPE) results in poor fire safety performance. The large addition of flame retardants leads to a significant decrease in mechanical properties. To solve above challenges, we design a multilayer core-shell flame retardant, piperazine pyrophosphate@ tannic acid@ Co amorphous hybrids (PAPP@TA@Co-2-MIM) and add it to TPE to enhance the fire safety and mechanical performance simultaneously. It was found that the addition of 32 wt% PAPP@TA@Co-2-MIM achieved a UL-94 V-0 rating of TPE composites, with a limiting oxygen index of 27 %. Compared to pure TPE, the peak heat release rate, total heat release, total smoke production, and peak CO release rate of TPE/PAPP@TA@Co-2-MIM were reduced by 79.8 %, 37.1 %, 42.9 %, and 82.5 %, respectively, effectively suppressing the release of heat, smoke, and toxic gases. Besides, the flame-retardant mechanism was also explained. In terms of mechanical performance, benefiting by the bridging effect of the core-shell structure, the tensile strength of TPE/PAPP@TA@Co-2-MIM increased by 52.7 %, compared to TPE/PAPP. This study designed a TPE composite material that showed good thermal stability, high fire safety performance and enhanced mechanical properties.

Thiazole-based flame retardant for polyamide vs. a sulfur-free flame retardant with similar phosphorus and nitrogen content

Polyamides are a promising candidate for the research of sulfur-containing flame retardants (FR). A new material based on 2-aminothiazole and 2-methyl-1,2-oxaphospholane-5-on-2-oxide is prepared and introduced into polyamide 12. To understand the effect of sulfur incorporation in its molecular structure, the new flame retardant is compared to a sulfur-free counterpart, revealing distinct variations in their self-extinguishing characteristics. The higher concentration of heteroatoms results in more flame diluting volatiles in the gas phase during thermal decomposition. The addition of the novel flame retardant containing phosphorus, nitrogen and sulfur, named TP, with only 5 m% into polyamide results in a UL-94 V-0 rating. Simultaneously, the limiting oxygen index increased to 31 %, compared to neat polyamide 12 with 24 %. Remarkably, the moisture absorption remains the same with the thiazole-based FR and the mechanical properties are only slightly decreased. This research reveals the flame retardant capabilities and advantages of a thiazole-based phosphorus compounds in polyamide.

Intrinsically Flame‐Retardant Polyamide 6 by Anionic Ring‐Opening Copolymerization with a Phosphorous‐Containing Comonomer

AbstractA three‐step synthetic route is established for the synthesis of a phosphorus‐containing ε‐caprolactam derivative, starting from cyclohex‐2‐enone and diphenylphosphinous chloride, followed by a Beckmann rearrangement. 2D NMR spectroscopy reveals that the phosphorus moiety is selectively localized at the 4‐position of the caprolactam ring. Different amounts of the phosphorus‐containing comonomer are systematically incorporated into polyamide 6 by anionic ring‐opening copolymerization with ε‐caprolactam at elevated temperatures. Polymerization reactions are initiated by a latent, CO2 protected N‐heterocyclic carbene in the presence of N‐acetyl caprolactam and MgCl2. The phosphorus content is determined by inductively‐coupled plasma‐optical emission spectroscopy (ICP‐OES) analysis. Limiting oxygen indices up to 23.5 are found for polymers containing ≈1 wt.‐% of phosphorus. The thermal properties of the copolymers are determined and compared to those of polyamide 6.

CoFe Oxides-Coated 2D Black Phosphorus for Flame-Retardant Nanocoatings with Tunable Mechanical Strength and Efficient Elimination of Toxic Gases.

2D black phosphorus (BP) degrades irreversibly into phosphate compounds under ambient conditions, which limits its application in a variety of fields. In this study, by coating amorphous ferric-cobalt oxides (CoFeO)on BP nanosheets, a multifunctional CoFeO@2D BP is successfully developed that effectively inhibited combustion and catalyzed CO oxidation to eliminate toxic gases. Strong affinity between transition-metal cations and BP allowed the uniform growth of amorphous ferric‒cobalt oxides on the BP surface, which effectively prevented the spontaneous degradation of 2D BP. By combining CoFeO@2D BP with gelatin and kosmotropic salts, the as-obtained nanocoatings are used for surface treatment of flammable polyurethane foam (PU). Kosmotropic ions induced strong hydrophobic interactions and bundling within the gelatin chains which significantly enhanced the mechanical performance of the PU. BP accelerates the carbonization of gelatin to inhibit the combustion of PU, and CoFe oxides, which act as true active centers to accelerate the oxidation of CO, effectively inhibiting the production of harmful gas. The release rate of CO decreases by 73% and the limiting oxygen index (LOI) increases from 17% to ≈32% during PU combustion. The developed novel 2D material opens the way for multifunctional coatings with integrated durability, flame retardancy, and high smoke suppression efficiency.

Construction of a hydrophobicity, phosphorus‐ and nitrogen‐containing layered double hydroxides‐based synergistic effect flame retardant for poly (lactic acid)

AbstractIn this work, a synergistic effect strategy was explored for fabricating hydrophobicity, phosphorus‐ and nitrogen‐containing layered double hydroxides nanosheets (LDHs) based flame retardant (LDHs‐K@DM). This fabricating process was achieved by amination of the surface of LDHs and, subsequently, interfacial self‐assembly with high P content of diethylenetriaminpenta (methylene‐phosphonic acid) (DTPMP) and high N content of melamine (MEL). The chemical construction and thermal stabilization properties of LDHs‐K@DM were confirmed via different characterization approaches. The results revealed that LDHs‐K@DM was successfully prepared and the surface of LDHs‐K@DM was transformed into hydrophobicity with high water contact angle. Moreover, LDHs‐K@DM had better thermal stability. After that, LDHs‐K@DM was molten compounded with biobased polylactic acid (PLA). It was suggested that LDHs‐K@DM were uniformly dispersed in the PLA matrix and could accelerate the decomposition of PLA to form char residues. Most importantly, the addition of 20 wt% LDHs‐K@DM into PLA can endow the composite to achieve a desirable UL‐94 V‐0 rating and the limiting oxygen index value of 30.9%. Finally, the synergistic effect flame retardant mechanism of LDHs‐K@DM was comprehensively analyzed. This synergistic decorating strategy for preparing LDHs‐K@DM flame retardant is promising for industrial production.

A P/Si-containing flame retardant towards simultaneous improvement of the toughness, transparency and fire safety of polycarbonate

Polycarbonate (PC) is a commonly used engineering plastic, but its poor flame retardancy limits its use. In this study, a DOPO-based flame-retardant (DOPO-TMTA) containing P and Si elements was synthesized via a simple method involving 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 2, 4, 6-trivinyl-2, 4, 6-trimethylcyclotrisiloxane (TMTA). The PC/mDOPO-TMTA (m = 4, 6, 8) composites were prepared by melt blending PC with different loadings of DOPO-TMTA. The prepared PC/DOPO-TMTA composites had excellent flame retardancy while maintaining good transparency. The limiting oxygen index (LOI) of PC/8DOPO-TMTA reached 32.5 % and achieved a UL-94 V-0 rating. Moreover, cone calorimetry tests revealed that, compared with those of pure PC, the peak heat release rate (PHRR) and total heat release (THR) of PC/8DOPO-TMTA decreased by 39.0 % and 38.1 %, respectively. Compared with pure PC, PC/mDOPO-TMTA also maintained good mechanical properties, and the tensile and impact strengths were slightly improved. The synergistic flame retardancy of DOPO-TMTA on P/Si elements for the PC matrix was revealed by condensed phase and gas phase product analysis. This work provides a good reference for the preparation of PC composites with high transparency and excellent comprehensive properties.

Preparation of high transparency, thermal stability, flame retardant polymethyl methacrylate nanocomposite via gamma-radiation polymerization

Achieving flame retardancy and thermal stability in poly(methyl methacrylate) (PMMA) while maintaining its inherent high transparency presents a significant challenge. In this work, we successfully fabricated an exceptional composite (P-SiO2-PMMA) with high transparency, flame retardancy, and thermal stability using 60Co γ-ray irradiation-induced copolymerization of methyl methacrylate (MMA), 2-hydroxyethyl 2-methyl-2-propenoate phosphate (HEMAP), and nano-silica (SiO2). The impact of the HEMAP on the crystal, optical, thermal stability, and combustion behavior properties of P-SiO2-PMMA has been investigated. P-SiO2/PMMA forms a three-dimensional network cross-linked molecular chain structure, enhancing the thermal decomposition temperature (Tdi), maximum thermal decomposition temperature (Tmax), glass transition temperature (Tg), and reducing the coefficient of thermal expansion (CTE). HEMAP and SiO2 significantly enhance the flame retardancy of the material. The limiting oxygen index (LOI) value of transparent flame-retardant 20-P-SiO2/PMMA composite material increased from 17.5% for PMMA to 23.2%, with a 47.3% decrease in peak heat release rate (PHRR). The flame retardant mechanism was also investigated. This study offers a novel approach for the industrial application of high transparency, thermal stability, and halogen-free flame-retardant PMMA composite.

Bio-derived epoxy thermosets incorporating imine linkages: Towards sustainable and advanced polymer materials

In the search for sustainable and eco-friendly alternatives, Schiff-based epoxy thermosets are emerging as a promising strategy due to the inherent dynamic and reversible nature of their imine functional groups, which enables thermal reprocessability and chemical recyclability. This article explores the synthesis of Schiff-based epoxy thermosets using sustainable approaches. Starting from vanillin or syringaldehyde, the synthesis involves the incorporation of imine linkages into the epoxy network. A new strategy has been employed by self-polymerization without the use of additional curing agents. This approach conducts to novel thermosets with superior material properties that exceed those reported in previous studies. Thermo-mechanical investigations showed that the designed thermosets have high mechanical properties, with storage moduli at room temperature ranging between 1.5–2.2 GPa, and glass transition values between 138 and 249 °C. Thermal analyses allowed to evaluate the Limit Oxygen Index (LOI) which ranged from 33 % to 36 %, demonstrating excellent flame-retardant properties without the addition of supplementary additives. Their reduced density (0.74–1.09 g/cm3) makes them suitable for applications where weight considerations are critical. These results obtained results place the designed Schiff-based materials as promising candidates for a wide range of high-end applications, particularly in industries that prioritize eco-friendly processes and materials.

Functionalized LDH via intercalation of gluconate anion and surface assembly of ultrafine copper hydroxide for improving mechanical properties and the fire safety of epoxy resin

To impart epoxy resin (EP) with outstanding mechanical properties and fire safety, LDH was systematically functionalized through gluconate anion (GA) intercalation followed by surface assembly of ultrafine Cu(OH)2, resulting in the LDH-GA@Cu(OH)2 hybrid. Comprehensive characterizations confirmed the successful synthesis of the desired product, with a uniform distribution of ultrafine Cu(OH)2 nanoparticles on the GA-intercalated LDH surface. The findings revealed that LDH-GA@Cu(OH)2 improved the mechanical properties of EP due to the increased LDH layer spacing, facilitating EP chain insertion, and the hydrogen bonding between the –OH of GA and the EP matrix. Fire retardancy tests indicated that the EP composite containing 7.5 wt% LDH-GA@Cu(OH)2 achieved a limiting oxygen index (LOI) of 30.1%. Furthermore, compared to pure EP, the composite demonstrated significant reductions in the peak heat release rate (PHRR) and peak CO production rate (PCOP) by 47.4% and 60.5%, respectively, underscoring its superior flame-retardant and toxic smoke suppression capabilities. Mechanistic studies further indicated that ultrafine Cu(OH)2 enhanced char formation through catalytic charring at the interface, which promoted compact and cohesive char layers. Overall, this work proposes a promising functionalization strategy for LDH to endow EP with excellent comprehensive performance.

A multifunctional epoxy composites based on cellulose nanofiber/carbon nanotube aerogels: Simultaneously enhancing fire-safety, thermal conductive and photothermal performance

As 5G technology develops and electronic power density increases, preparing epoxy resin (EP) composites with excellent fire-safety, thermostability, and thermal conductivity remains challenging. Herein, hexaphenoxy cyclotriphosphazene and poly(piperazine methylphosphonic acid pentaerythritol ester) were used as synergistic flame retardants (FR) for EP. The cellulose nanofiber/carboxylated multiwalled carbon nanotubes aerogels (CCA80) were prepared and immersed into the EP and FR mixture to obtain EP/CCA80/FR composites. Compared with neat EP, the limiting oxygen index of EP/CCA80/6 wt% FR increased by 38.9 %, the total heat release and CO2 production rate decreased by 30.61 % and 39.47 %, respectively, achieving the UL-94 V-0 rating. Moreover, its thermal conductivity was 1.06 W · m−1·K−1, 457.9 % higher than neat EP, while maintaining excellent electrical insulation. Its surface temperature maintained at 94.5 °C under 1.0 kW·m−2 irradiation for 2 h, exhibiting good photothermal conversion capability and photobleaching resistance. A novel fabrication methodology of multifunctional EP composites for high-performance electronic component was proposed.

Multi‐component coupling synergistic effect of resourced gold tailings on intumescent flame‐retardant polypropylene

AbstractAddressing the challenge of resource utilization of gold tailings. A high performance flame‐retardant fillers (K‐GTF) were prepared from gold tailings (GTF) by coupling and condensation for application to intumescent flame‐retardant polypropylene (PP). K‐GTF enhances the flame‐retardant, thermal stability, smoke suppression and mechanical properties of flame‐retardant PP through synergistic approach. The results show that K‐GTF demonstrates good flame‐retardant synergism, with PP composites containing 3% additive (PP/G3) exhibiting substantial flame‐retardant and smoke suppression characteristics. Notably, PP/G3 boasts a limiting oxygen index (LOI) of 36.1%, which is substantially higher than the 33.6% LOI of the flame‐retardant PP without added K‐GTF (PP/G0). Furthermore, the peak heat release rate (PHRR), peak smoke production rate (PSPR), total heat release rate (THR), and total smoke production (TSP) of PP/G3 were decreased by 32.5%, 26.9%, 31.6%, and 21.5%, respectively, as compared to PP/G0. According to the synergistic mechanism analysis, K‐GTF exerts a multi‐component coupling synergistic effect, which promotes the production of phosphorus‐rich cross‐linking structures in flame‐retardant PP materials during the combustion, thereby promotes the formation of stable, dense and intumescent char to further enhances the flame‐retardant performance of the PP materials. In terms of mechanical effects, the introduction of K‐GTF alleviates the issue of a substantial decline in mechanical properties typically caused by flame retardants in PP materials. This indicates that K‐GTF improves the compatibility between the flame retardants and the PP matrix, thereby enhancing the mechanical properties of the flame‐retardant PP materials.Highlights Successfully synthesis a flame‐retardant synergist (K‐GTF). K‐GTF has good synergistic flame‐retardant effect. K‐GTF substantially enhances char formation and thermal stability of flame‐retardant PP. K‐GTF exerts a multi‐component coupling synergistic effect. K‐GTF enhances the compatibility between the PP matrix and the flame retardants.

Facile Construction of Flame-Resistant and Thermal-Insulating Sodium Alginate Aerogel Incorporating N- and P-Elements.

In this study, sodium alginate (SA) aerogel cross-linked with Ca2+ was selected as the basic skeleton to construct a lightweight, flame retardant, and thermal insulating composite aerogel via modification with melamine and phytic acid. The resulting aerogel, SA-1.0 MP, achieved a thermal conductivity as low as 0.0379 W/(m·K). Compared to pristine SA aerogel, SA-1.0 MP demonstrated improved fire resistance, evidenced by a substantial increase in the limiting oxygen index (LOI) from 21.5% to 48.8% and a V-0 rating in the UL-94 test. Furthermore, a synergistic mechanism was proposed to explain its remarkable flame-retardant capability.