Search Results (881)

Epoxy resins are widely used in advanced engineering applications, including coatings, adhesives, and electronics. Therefore, improving their flame resistance is important for enhancing fire safety and extending their range of applications. A series of flame retardants based on melamine phosphate derivatives, such as melamine phosphate (MP), melamine dibutyl phosphate, and melamine bis(2-ethylhexyl) phosphate, as well as a zinc borate-modified system (ZnB-MP) has been incorporated into commercially available epoxy resin (Epidian® 601). The blends were characterized using Fourier transform infrared spectroscopy (FTIR) to confirm their chemical structure. Thermal behaviour was investigated using differential scanning calorimetry and thermogravimetry coupled with FTIR gas analysis (TG-FTIR). The flammability performance of the epoxy blends was evaluated using pyrolysis combustion flow calorimetry, which allowed parameters such as heat release rate, total heat release, and heat release capacity to be determined. The incorporation of melamine phosphate-based flame retardants was found to significantly reduce the flammability of epoxy blends, leading to substantial decreases in heat release rate, total heat release, and heat release capacity. The most pronounced effect was observed in systems containing higher concentrations of MP and in cooperative ZnB-MP formulations. Full article

A novel material, chitosan oligosaccharide@melamine polyphosphate (CMP), with enhanced flame-retardant and hydrophobic properties, was synthesized by cross-linking melamine polyphosphate (MPP) with chitosan oligosaccharide. Compared with MPP, the CMP overcomes its inherent drawbacks when used as a flame retardant in polylactic acid (PLA) composites, namely the high loading demand and unsatisfactory interfacial compatibility with the polymer matrix. The results demonstrated that the peak heat release rate (p-HRR) dropped significantly in comparison to pure PLA, from 304.69 kW·m⁻² to 210.39 kW·m⁻², while the fire performance index (FPI) increased from 0.1 to 0.48 s·m⁻²·kW⁻¹. Furthermore, the fire growth index (FGI) decreased from 1.51 kW·m⁻²·s⁻¹ to 1.03 kW·m⁻²·s⁻¹. Additionally, the CMP demonstrated enhanced thermal stability, making the pyrolysis activation energy E_α increase from 135.04 to 191.97 kJ/mol during 308~416 °C by pyrolysis kinetics. Compared to composite PLA incorporating pristine MPP, the CMP-modified counterpart exhibits superior mechanical properties and significantly enhanced hydrophobicity, evidenced by a maximum water contact angle reaching 93.96°. It provides a strategy for adapting phosphorus-based flame retardants for PLA, thereby broadening their applicability across diverse scenarios. Full article

The growing application of nanotechnology in wood modification has led to significant improvements in the durability, fire resistance, and biological stability of wood-based building materials, such as glued laminated timber (GLT), as well as related chemical products, including fire retardants and anticorrosion preservatives. While numerous review papers have focused on material performance and functionalisation strategies, a comprehensive analysis of the research methodologies employed in this field remains limited. This review addresses this gap by systematically examining the experimental and analytical methods used in studies on nanomaterial-modified wood surface treatments. Scientific articles published and indexed in the Web of Science and Scopus databases within the last ten years were selected using keywords related to wood, nanotechnology, and surface applications simulating industrial timber treatment processes applied in factories and construction sites. Publications were screened according to predefined inclusion and exclusion criteria. The study selection process was conducted according to the PRISMA methodology, and 74 studies meeting the inclusion criteria were selected for the final analysis. Extracted methodological features were coded and analysed using frequency-based descriptive statistics. Considerable methodological heterogeneity was observed among the analysed studies. Softwood species, TiO₂- and ZnO-based nanomaterials, and brushing or immersion treatments represented the most frequently investigated research configurations. Scanning electron microscopy (SEM), often combined with EDS and XRD analyses, occupied a central role within the analytical framework of nanomodified wood research. In contrast, long-term durability assessments, biological resistance testing, and fire-performance evaluations were comparatively underrepresented. The review also revealed substantial variability in the use of testing standards and statistical methods. By linking research methodologies to normative requirements for construction materials, this work provides a methodological framework supporting future research, standardisation, certification, and commercial implementation of nanomaterial-based wood protection systems. Full article

Conventional polyurethane (PU) grouting materials face a severe trade-off between curing exotherm safety, flame retardancy, and mechanical performance in deep coal mining. Herein, we propose a synergistic strategy combining chemical prepolymerization with fly ash (FA) incorporation to develop high-performance prepolymer-based polyurethane/fly ash (PUP/FA) composite grouting materials. Prepolymerization combined with FA addition successfully mitigated the maximum reaction temperature to 98.3 °C while sustaining a rapid curing rate within 3 min. At an optimal FA loading of 20 wt%, the PUP/FA-20% composite sustained a robust compressive strength of 42.5 MPa, satisfying underground reinforcement standards. Crucially, limiting oxygen index (LOI) and cone calorimetry tests demonstrated outstanding flame retardancy and smoke suppression; the LOI reached 28.5%, and the total smoke production plummeted to 21.3 m². This performance enhancement is governed by a synergistic mechanism where dimethyl methylphosphonate acts via gas-phase radical scavenging, while uniformly dispersed FA particles serve as rigid barrier nodes to construct a dense protective shield in the condensed phase. This work offers a highly effective, waste-valorized, and fire-safe grouting solution for sustainable deep-underground engineering reinforcement. Full article

Despite their high effectiveness in reducing material flammability, modern brominated flame retardants (BFRs) remain poorly understood with respect to the toxic substances they generate during combustion. BFRs such as 1,2-bis(pentabromodiphenyl)ethane (DBDPE) and tetrabromophthalate diol (PHT4-DIOL) have been introduced following the limitations on legacy brominated additives. However, their thermal decomposition pathways and toxic product emission profiles under real fire conditions remain poorly characterized. Exposure to elevated temperatures may promote the formation of halogenated toxicants and environmentally persistent compounds, raising concerns that extend beyond conventional fire-safety performance. The combustion behavior of DBDPE-, PHT4-DIOL-, and BFR-containing epoxy resins was investigated using a steady-state tube furnace designed to reproduce realistic fire scenarios. Controlled temperature and ventilation conditions were applied to simulate representative stages of fire. Combustion emissions were comprehensively characterized using Fourier transform infrared spectroscopy (FT-IR) to analyze asphyxiant and irritant gases and solid-phase microextraction gas chromatography–mass spectrometry (SPME-GC-MS) for volatile and semi-volatile organic compounds. The results presented that the incorporation of BFRs substantially altered combustion emission profiles, promoting the formation of brominated and mixed-halogenated species alongside toxic gaseous products. Significant differences in the composition and distribution of combustion byproducts were observed between non-modified and BFR-containing materials, indicating that the environmental and toxicological consequences of these additives cannot be adequately assessed solely through flammability-reduction metrics. These conclusions provide new knowledge of the environmental impacts of brominated flame retardants and highlight the importance of integrated fire-safety assessment strategies that simultaneously consider flame-inhibition efficiency, combustion toxicity, and environmental persistence. Full article

To investigate the effects of different surface coating treatments on the fire resistance of Qing Dynasty traditional corridor-style timber structures, the Long Corridor of the Beijing Summer Palace was selected as the case study. Two representative timber species, red pine and larch, were examined under three treatment conditions, including no treatment, traditional treatment (“San-dao-hui” and “Yi-ma-wu-hui”), and composite treatment combining traditional treatment with modern flame-retardant coatings. Cone calorimeter (CC) testing and Fire Dynamics Simulator (FDS) simulation were used to systematically investigate their combustion performance and fire spread patterns. Results indicate a clear, gradual improvement in timber reaction to fire: composite treatment coating performed best, followed by plaster layer protection, and untreated wood performed the worst. Among these, the composite treatment of red pine with “Yi-ma-wu-hui” (one hemp layer and five lime plaster layers) combined with modern flame-retardant coating showed the highest overall efficacy. The time to ignition (TTI) reached 76.7 s, a 210.5% increase compared with untreated wood. Meanwhile, peak heat release rate and carbon monoxide production were both significantly reduced. Notably, the selected modern flame-retardant coating cures colorless and transparent, preserving the original appearance of the wood, and the composite treatment maintains the historical texture and color consistency required for heritage restoration. The flame-retardant efficiency of the “Yi-ma-wu-hui” plaster layer was superior to that of the “San-dao-hui” (three lime plaster layers), owing to its denser structure that provides a stronger physical barrier effect. Larch exhibited better inherent reaction to fire than red pine, and surface coating treatments effectively reduced differences between substrates. FDS simulations confirmed that the composite treatment could keep peak heat release rate below 6000 kW under the most adverse meteorological conditions, confining high temperatures and dense smoke near the ignition point and effectively restraining sequential fire spread in traditional corridor-style timber structures. These findings provide a scientific basis and practical guidance for the fire-resistant restoration of Qing Dynasty traditional corridor-style timber structures and similar heritage buildings. Full article

Fire is the core safety threat to the survival and development of timber-framed buildings, and passive fire prevention intervention is the core foundation of fire protection systems for timber-framed buildings. Existing reviews suffer from limitations such as incomplete scenario coverage, insufficient breakdown of intervention mechanisms, and a lack of methodological standardization. This study strictly followed the PRISMA 2020 systematic review guidelines, searching the relevant literature from January 2016 to April 2026 on the Web of Science, Scopus, and Science Direct databases. After standardized screening, 89 valid articles were finally included and a systematic study was conducted through bibliometric analysis, keyword visualization, and multi-dimensional classification coding. The results show that the number of publications in this field has been continuously increasing from 2016 to 2025, with China accounting for 31.46% of the total, ranking first globally. The study constructed a core intervention mechanism system for passive fire prevention in timber-framed buildings, covering four categories: intrinsic flame-retardant modification, isolation protection, structural optimization, and spatial control. The working principles, application effects, advantages and disadvantages, and engineering application scenarios of each mechanism were clarified. This study systematically sorts out the core intervention mechanisms of passive fire prevention in timber-framed buildings, clarifies the research status and development trends in this field, and can provide evidence-based support for the design optimization, technology development, and engineering practice of passive fire protection for timber buildings. Full article

There is growing interest in the development of sustainable thermal insulating materials from renewable resources, a strategy which can stand as an alternative to conventional petroleum-based insulating materials. In this study, bio-based porous insulating materials derived from partially hydrolyzed collagen (rabbit-skin) and containing ammonium polyphosphate (APP) as flame retardant and miscanthus fibers as reinforcement are prepared. Four freeze-dried formulations were prepared: pure partially hydrolyzed collagen (COL), partially hydrolyzed collagen with APP (COL-APP), partially hydrolyzed collagen with miscanthus particles (COL-M) and a ternary formulation that included both additives (Col-APP-M). The density, porosity, thermal conductivity, specific heat capacity, compressive mechanical properties and fire behavior were evaluated. The neat collagen foam had the lowest density (122 kg·m⁻³), highest porosity (91%), and lowest thermal conductivity (0.045 W·m⁻¹·K⁻¹). The addition of APP and/or miscanthus increased density and showed limited change in thermal conductivity, which remains comparable with insulating materials (0.0445–0.0510 W·m⁻¹·K⁻¹). Specific heat capacities of partially hydrolyzed collagen foams were also relatively high (1319–1390 J·kg⁻¹·K⁻¹) as compared to some other typical insulating materials. Mechanical experiments demonstrated that APP had considerably improved the compression stiffness and strength through the physical crosslinking and densification effects in the partially hydrolyzed collagen network. Analysis of fire behavior with both Pyrolysis Combustion Flow Calorimetry (PCFC) and cone calorimetry further indicated that the addition of APP yielded improved flame retardancy with a very low heat release. These results showed that partially hydrolyzed collagen-based foams reinforced by APP and lignocellulosic particles are sustainable thermal insulation materials with desired thermal performances, improved mechanical stability, and enhanced flame retardancy. Full article

Wood’s inherent flammability, arising from its cellular organic composition, demands effective protective strategies. This study aimed to develop a multifunctional bio-based wood coating simultaneously integrating flame retardancy, optical transparency, moisture-triggered self-healing, and surface hydrophobicity within a single formulation. An intumescent flame retardant (PAGHR) was synthesized via ionic assembly of a phytic acid–phosphorylated polyethylene glycol conjugate (PgP) with a piperazine–etidronic acid salt (HEPHR), subsequently blended with gelatin (G) and surface-finished with fluorosilane. The optimized coating (G/PAGHR-4) achieved a limiting oxygen index (LOI) of 37.2% and passed the UL-94 V-0 rating. Cone calorimetry demonstrated reductions of 75.1% in peak heat release rate (pHRR) and 50.0% in total heat release (THR) relative to the neat gelatin control. Char yield at 700 °C increased substantially from 17.8 wt% to 41.0 wt%, confirming effective condensed-phase char promotion. Beyond fire performance, the coating maintained high visible-light transmittance, preserved natural wood aesthetics, and achieved macroscopic scratch healing within 40 min upon ambient water contact. Fluorosilane finishing elevated the water contact angle to 122°. These results establish a scalable, environmentally friendly strategy for multifunctional bio-based protective coatings applicable to wood, textiles, and polymer substrates. Full article

Polymeric materials face serious fire-safety challenges in construction, electrical and electronic devices, and aerospace because of their high heat release, melt-dripping tendency, and severe smoke and toxic emissions during burning. This review systematically summarizes the roles of nanofillers in the fire safety of polymer nanocomposites across three interconnected levels: functional mechanisms, regulatory factors, and macroscopic fire behavior. It focuses on four main mechanisms, namely physical barriers, catalytic charring, free-radical scavenging, and rheological network reconstruction, and further discusses how filler geometry, loading level, interfacial compatibility, dispersion state, and spatial orientation regulate fire-safety performance. By linking these factors to time to ignition, thermal stability, heat release, flame spread, and smoke emission and toxicity, the review clarifies the intrinsic structure–mechanism–property relationships. Current studies indicate that the fire-safety improvements provided by nanofillers do not arise from any single effect, but from their coupled regulation of heat transfer, mass transfer, radical reactions, and high-temperature rheology throughout thermal degradation, ignition, heat release, flame spread, and smoke and toxic-gas emission. Remaining challenges include the lack of unified evaluation criteria, limited in situ mechanistic evidence, and insufficient application-oriented rational design. Future work should establish verifiable, comparable, and predictive structure–mechanism–property relationships for polymer nanocomposites. Full article

This study reports the physicochemical characterization and structure–property relationships of rigid sheep wool/phenolic novolac panels developed as bio-based thermal insulation for building envelopes. Mixed Polish sheep wool was washed, mechanically opened, and formed into nonwoven mats, then impregnated with either neat or flame-retardant novolac resin to obtain lightweight boards with a fiber content of about 50 wt%. Elemental analysis, ICP-OES, FTIR spectroscopy, and laser and electron microscopy were used to evaluate the fiber composition, keratin structure, morphology, and fiber–matrix interfaces. Mechanical performance under three-point bending and shear, differential scanning calorimetry, thermogravimetric analysis, and transient hot-probe thermal-conductivity measurements were applied to link microstructure with functional behavior. Novolac impregnation transformed the compliant wool mat into self-supporting panels, increasing the flexural modulus to the 0.8–1.4 GPa range and flexural strength to approximately 48–52 MPa, while the shear modulus and work to failure rose by more than an order of magnitude relative to the loose wool reference. Thermal conductivity remained in a typical range for natural-fiber insulations (λ = 0.061 W·m⁻¹·K⁻¹ for the wool mat and 0.071–0.074 W·m⁻¹·K⁻¹ for the composites), although higher than that of expanded polystyrene. DSC and TGA confirmed that wool fibers remain thermally stable up to about 200–220 °C, that the novolac resin cures around 140 °C, with typical phenolic reaction enthalpies, and that both formulations generate high char residues of roughly 60–80 wt% at 600 °C under nitrogen, evidencing a strong charring propensity rather than directly quantifying fire resistance. Overall, the results position sheep wool/novolac panels between conventional bio-based insulation and structural composites and highlight their potential as sustainable, circular insulation materials for energy-efficient building envelopes. Full article

To meet the requirements of forest fire prevention, a water glass-based composite gel foam was developed by introducing hydroxypropyl methylcellulose (HPMC) and nanosilica sol into a sodium silicate/sodium bicarbonate matrix. The resulting water glass/HPMC/silica sol ternary system (SGF-HPMC-SOL) was designed to improve water retention, foam stability, substrate adhesion, and fire-barrier durability. The results indicate that HPMC and silica sol contributed to network reinforcement through hydrogen bonding, polymer-chain entanglement, nanoscale filling, and possible interfacial condensation. The optimized SGF-HPMC-SOL retained 20.4% of its initial mass after heating at 100 °C for 5 h, compared with 4.65% for SGF and 9.54% for SGF-HPMC; reached a carbonization time of 164 s under direct-flame exposure, versus 100 s for SGF and 137 s for SGF-HPMC; and maintained a residual mass of 76% at 800 °C in TGA, compared with 58.3% for SGF and 55.1% for SGF-HPMC. These improvements were associated with the formation of a denser silica-rich protective layer after combustion, which delayed heat transfer to the wood substrate. Under the adopted direct-flame screening conditions, SGF-HPMC-SOL exhibited enhanced flame-retardant performance compared with the reference gel foams, indicating its potential for enhanced flame-retardant performance under laboratory screening conditions for forest fire prevention. Full article

Magnesium hydroxide is attracting growing interest as a versatile, halogen-free flame retardant, and this review surveys its production routes, structure–property relationships and use in polymer systems from commodity polyolefins to advanced bio-based materials. Industrial Mg(OH)₂ is still predominantly obtained from mining or hydration of MgO, but increasing attention is being devoted to recovery from seawater and saltwork brines, where precipitation from Mg²⁺-rich streams followed by controlled rehydration or direct precipitation yields fine, high-purity powders suitable for flame retardant use and simultaneously valorizes saline wastes. In parallel, hydrothermal synthesis has been extensively explored to tailor particle size and morphology by adjusting the precursor, solvent, temperature and time, enabling high-surface-area Mg(OH)₂ or MgO with narrow size distributions that are attractive for high-performance composites also evaluated via ball milling, crushing and refining. More recently, process intensification strategies such as microwaves and ultrasounds have been proposed to shorten reaction times, lower temperatures and better control nucleation and growth, opening paths toward energy efficient production of structured Mg(OH)₂ from both conventional and brine-derived precursors. The second part of the review analyzes how the intrinsic endothermic decomposition and basic character of Mg(OH)₂ can be utilized across a broad range of polymer matrices and how surface functionalization strategies extend its applicability. In addition to “as received” powders, stearic acid and other fatty acids, metal soaps and various organic coupling agents are widely used to render the surface more hydrophobic, enhance dispersion and interfacial adhesion, and in some cases introduce additional char-forming or barrier functionality. In terms of the application, the review methodically synthesizes and contrasts fire and mechanical data for Mg(OH)₂-containing polyolefins (HDPE, LLDPE, PP and EVA) utilized in cables and building products, expandable polymers and foams, biopolymers (PLA and PBS), and elastomers. The review places particular emphasis on the balance between loading level, processability, flame performance and mechanical integrity. This review aims to provide a comprehensive framework for designing next-generation Mg(OH)₂-based flame-retardant systems for both conventional and emerging polymer technologies. To this end, it integrates advances in sustainable feedstocks, controlled synthesis and surface engineering with the rapidly expanding application space. Full article

Waterborne polyurethane (WPU) is widely used in flexible films and textile finishing, but its intrinsic flammability, severe melt dripping, and sensitivity to polar additives restrict its fire-safe applications. Herein, a phosphorous acid-protonated chitosan (PCS) was designed as an emulsion-adaptable bio-based modifier and incorporated into cationic WPU via a facile aqueous blending route, yielding transparent multifunctional composite films and flame-retardant textile coatings. Unlike conventional flame-retardant WPU systems that rely on reactive monomers or suffer from poor emulsion compatibility, this work proposes an emulsion-compatible strategy based on PCS, enabling the simultaneous integration of dispersion stability, flame retardancy, and antibacterial functionality within a single system. PCS could be stably accommodated in the WPU latex without visible precipitation or demulsification after centrifugation, and the resulting films preserved a continuous matrix structure with uniformly distributed PCS-rich nanodomains. Rheological analyses revealed that the polar groups of PCS established strong intermolecular associations with urethane segments, strengthening the physical network. The char residue at 700 °C increased from 0.7 wt% for neat WPU to 32.7 wt% for WPU/PCS-5. Meanwhile, WPU/PCS-5 achieved a limiting oxygen index of 35.4% and a UL-94 V-0 rating, while its peak heat release rate and total heat release were reduced by 73.4% and 41.8%, respectively. The composite films also showed nearly complete antibacterial efficiency against Escherichia coli and Staphylococcus aureus. As a textile coating, WPU/PCS-5 enabled immediate self-extinguishing of cotton fabric, increased the limiting oxygen index from 18.5% to 27.2%, and reduced the damaged length from 30.0 to 11.0 cm. This work demonstrates that an emulsion-compatible strategy based on PCS can effectively integrate dispersion stability, fire safety, multifunctionality, and coating applicability into WPU materials. Full article

Materials applied in interior and non-structural aircraft components are required to satisfy rigorous safety and performance criteria, especially with respect to flame retardancy and wear resistance. Ultem 9085, a high-performance polyetherimide thermoplastic, is extensively used in aerospace applications owing to its advantageous strength-to-weight ratio and compliance with flame, smoke, and toxicity (FST) requirements. Nevertheless, the application of surface coatings, including paints, may modify their fire-retardant and tribological performance, with potential implications for service behavior and regulatory compliance. This work provides new insight into the behavior of painted Ultem 9085 components under fire exposure and frictional loading, addressing the critical need to determine whether surface finishing affects the material’s inherent performance advantages. Thus, the effects of different paint coatings on the fire-retardant and tribological properties of Ultem 9085 are investigated. Test specimens were manufactured using a Stratasys F900 system with 100% infill density and geometries adapted for standard vertical burn and heat release tests. Fire performance testing, including vertical burn, smoke and toxicity, and heat release rate, was performed in accordance with CS/FAR 25 Appendix F and AITM 3-0005 requirements. Tribological behavior was assessed using a ball-on-flat tribometer under dry-sliding conditions, while surface texture was analyzed using 3D profilometry. Seven polymer–coating composites were examined. It was experimentally confirmed that all coatings reduced vertical burn length but increased peak heat release rate and smoke density relative to unmodified Ultem 9085. Tribological results varied significantly, highlighting the critical role of paint selection in achieving optimal fire safety and wear resistance. Full article