Specific Extinction Area Research Articles

Facile preparation, pyrolysis and pilot production a bamboo scrimber with halogen-free, flame-resistance and low-smoke

It has been challenging for academia and industry to manufacture fire-safe bamboo materials. In this study, a low-cost, simple, efficient, and environment-friendly composite flame retardant system has been reported for the laboratory preparation and pilot production of bamboo scrimber. Bamboo bundles were immersed in a P-N-B (phosphorus-nitrogen-boron) complex solution derived from halogen-free compounds without external pressure to obtain unique bamboo scrimber construction units. The second exothermic peak of bamboo scrimber was delayed by 478 s, the peak of heat release rate (PHRR), the peak of mass loss rate (PMLR), the peak specific extinction area (PSEA), and the total smoke release (TSR) dropped by 48.0 %, 76.3 %, 81.3 %, and 92.3 %, respectively, in the laboratory study. It’s flame retardancy and smoke suppression properties were substantially improved, which is attributed to the synergistic catalytic carbon formation effect of P, N, and B elements. In the thermal cracking experiments, the combustible gas content from thermal cracking of bamboo decreased while the refractory gas content increased. Pilot test studies showed that the fire performance of large bamboo scrimber blocks with dimensions of 1900 mm × 145 mm× 145 mm and density ≥ 1.26 meet the requirements of flame-retardant class B1 as stipulated in GB 8624-2012. The potential applications of this technology are envisioned for flooring and other industrial applications of decorative bamboo materials.

CHARACTERIZATION OF THE BURNING OF ORIENTED STRAND BOARDS EXPOSED TO FLAME

Since the methods based on the interaction of a relatively low intensity flame on the lignocellulose sample surface often do not allow measuring the heat release rate (HRR), a procedure using oxygen consumption calorimetry was proposed. The method was applied to OSB samples with dimensions of 320 mm x 140 mm x 25 mm placed in a vertical position. During the measurement, in addition to the HRR, the production of smoke, which was significant after stopping the burner, was also monitored. The average net value of HRR at burner outputs of 3 kW, 4 kW and 5 kW was 2.339 kW and the smoke specific extinction area was in the range of 10.88 m2.kg-1 and 13.19 m2.kg-1.

Preeminent Flame-Retardant and Smoke Suppression Properties of PCaAl-LDHs Nanostructures on Bamboo Scrimber.

Bamboo scrimber is widely used in interior decoration, architecture, and many other fields. However, it has caused huge security risks due to its inherent flammability and easy-to-produce toxic volatiles after combustion. In this work, the bamboo scrimber with superior flame retardant and smoke suppression properties was produced via the coupling of phosphocalcium-aluminum hydrotalcite (PCaAl-LDHs) with bamboo bundles. The results demonstrated that the flame-retardant bamboo scrimber (FRBS) heat release rate (HRR) and total heat release (THR) were, respectively, reduced by 34.46% and 15.86% compared with that of untreated bamboo scrimber. At the same time, the unique multi-layer structure of PCaAl-LDHs effectively slowed down the release rate of flue gas by extending its escape path. Cone calorimetry showed that the total smoke emissions (TSR) and specific extinction area (SEA) of FRBS were, respectively, reduced by 65.97% and 85.96% when the concentration of the flame retardant was 2%, which greatly developed the fire safety of the bamboo scrimber. This method not only improves the fire safety of bamboo scrimber but can also be expected to broaden its use scenarios.

Geometrical and environmental effect on fire behaviour of polyurethane foam slabs

AbstractThis study presents the results of a set of large‐scale fire tests performed on horizontal polyurethane foam slabs. Slab thickness, ignition location, and environment (free burn or corner wall) were varied over 23 individual tests. In a continuation of a previous study by the authors, four different slab thicknesses, five different ignition locations, and three environmental modification combinations were tested to examine the potential effects these parameters may have on the test outcomes. Wall configurations were composed of either gypsum plaster board or particle board wall linings and enclosed two sides of the foam slabs. The results obtained were heat release rate, peak HRR, total heat release, and effective heat of combustion, smoke production rate, total smoke production, specific extinction area and soot yield along with flame spread rate calculations obtained using a specifically designed sample tray. These were then analysed to quantify the effects of the test input parameter changes. Results highlight the influence of test input parameter changes on almost all the chosen fire metrics analysed. Slab thickness showed relatively straight forward linear changes to global metrics such as total heat release and total smoke production, while effective heat of combustion showed no change. The smoke production parameters of specific extinction area and soot yield showed minor trends towards higher values with increased slab thickness. Flame spread rates also showed an increased velocity with thicker slabs. Changes to the environment surrounding the foam slabs, from a free‐burning scenario to a corner wall configuration that obstructed two sides of the foam slab generally resulted in faster growth of HRR and higher peak values when compared to the free‐burn tests. This outcome was most obvious for the wall tests using combustible materials, where growth rates were comparative to an ultra‐fast t^2 fire, and peak HRR value rose to over triple that of the free‐burn test results. Flame spread rates were highly impacted by the addition of a corner wall, spread rates increased, and the overall pattern of spread rates across the face of the slabs changed entirely. The influence on smoke production values was minor, and for other smoke metrics, the scenario changes showed little influence. However, the values obtained for soot yields were approximately an order of magnitude lower than those given in standard reference books, such as the SFPE handbook for flexible polyurethane foam. This was an interesting additional finding as soot yield values are often directly used in CFD models to simulate smoke spread and determine life safety criteria in fire safety engineering (FSE).

UV-LED Curable Acrylic Films Containing Phosphate Glass Powder: Effect of the Filler Loading on the Thermal, Optical, Mechanical and Flame Retardant Properties.

In this work, we thoroughly investigate the effects of the incorporation of a phosphate glass micrometric powder on the morphology, as well as on the thermal, optical, mechanical and flame retardant properties of UV-LED curable acrylic films. To this aim, the filler loading was changed within 10 and 50 wt.%. UV-LED initiated curing was selected as a fast and reliable system, as the standard UV-curing process was not suitable because of the presence of the glass powder that decreased the quantum efficiency during the UV exposure, hence preventing the transformation of the liquid system into a solid network. The glass powder slightly increased the glass transition temperature of the acrylic network, hence showing a limited effect on the chain segments mobility; besides, increasing filler loadings were responsible for a progressive decrease of the transparency of films, irrespective of a marginal effect on their refractive index. Conversely, the presence of increasing amounts of phosphate glass improved the thermal and thermo-oxidative stability of the cured products. Besides, phosphate glass was capable of remarkably enhancing the flame retardance of the acrylic network at 50 wt.% loading, which achieved self-extinction in vertical flame spread tests (and was V-0 rated). This formulation, as assessed by forced-combustion tests, also displayed a remarkable decrease of peak of Heat Release Rate and Total Heat Release (by 44 and 33%, respectively) and of Total Smoke Release and Specific Extinction Area (by 53 and 56%, respectively). Further, the filler promoted an increase of the stiffness and surface hardness of the films, at the expense of a decrease in ductility. All these findings may justify the potential use of these composite films as flame retardant coatings for different flammable substrates.

Synergistic interaction between inorganic layered materials and intumescent fire retardants for advanced fire protection

Intumescent fire-retardants (IFR) are widely applied in fire protection coatings of steel and wooden structures. The addition of inorganic fillers, such as layered ionic clays, can improve the fireproof performance of IFR coatings. However, a fundamental insight of how these filler materials synergistically interact with the IFR materials remains elusive. In this study, we address this fundamental knowledge gap by systematically investigating the synergy between the IFR fire protection coatings and the CaAlCO3-layer double hydroxide (LDH) or montmorillonite (MMT) fillers, which render substantially longer fire resistance (>20 min), reduced specific extinction area (by 54.7 and 44.1 m2 kg−2, respectively), and reduced heat release (by 0.9 and 0.7 MJ m−2, respectively). Combining experimental results and density functional theory calculations, we show for the first time that the superior fireproof performance of the MMT-IFR fire coating originates from the chemical modifications of the char layer by Si-doping. The chemical stabilisation of the silicon- and nitrogen-doped graphene (Si–N-G) structures improves the oxidation resistance of the char layer. Additionally, the formation of the Si–N-G structures with limited lattice deformation stabilised the porous morphology of the char layer, thereby promoting its heat-shielding performance.

Nano CaAlCO3-layered double hydroxide-doped intumescent fire-retardant coating for mitigating wood fire hazards

A novel approach was proposed to reduce the risk of fire posed by wood by using a flexible and highly efficient intumescent coating doped with CaAlCO3-layered double hydroxides (LDH). The fire-retardant performance of the coating was investigated through fire tests, cone tests, and thermogravimetry. After the fire tests, the residual char layer was characterized using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The coating with 2.2 wt% CaAlCO3-LDH exhibited the fire resistance of more than 20 min, reduced the specific extinction area by 54.78%, and increased the residual mass to 13.5%. Density functional theory illustrated that the superior porous honeycomb char layer and oxidation resistance obtained are due to the chelation effect of Ca and Al on the changes in polyaromatic structures. This study presents a new type of LDH-doped fireproof coating for minimizing the fire-hazardous nature of wood.

A milligram‐scale flame calorimeter pyrolyzer system used to emulate burning of nonthermally thin solid samples

SummaryA new Milligram‐scale Flame Calorimetry (MFC) pyrolyzer system was developed to approximate heating conditions experienced by material samples in gram‐scale tests, such as cone calorimetry. The main features of this pyrolyzer system are a miniature flat heating coil embedded into a platform supporting the sample crucible. The use of a constant power rather than a constant heating rate operation mode distinguished the new MFC from the other mg‐scale flammability test method—microscale combustion calorimetry (MCC). A series of tests was carried out using the new MFC, cone, and MCC on five synthetic polymers representing a wide range of flammability behavior. All methods produced similar solid residue yields. The MFC peak heat release rate (HRR) was found to correlate linearly with the cone peak HRR (R2 = 0.93). The MCC peak HRR did not exhibit a strong correlation with the corresponding cone data. The new MFC was found to produce heat of combustion (HOC) values nearly identical to those measured in cone calorimetry. The MCC had a tendency to produce higher heats of combustion. Both MFC and MCC measured sample ignition temperatures that showed some correlation with the square root of the time to ignition measured in a cone calorimeter. The MFC airborne particular yield was found to correlate well (linear R2 = 0.91) with the average specific extinction area measured in the cone tests. It was concluded that the newly designed MFC can deliver relatively accurate flammability measurements similar to cone calorimetry while using three orders of magnitude smaller samples.

Are Ionic Liquids Suitable for Suppressing Coal Spontaneous Combustion?

Due to the reported fact that the active functional groups in coal can be dissolved and destroyed by ionic liquids, it is expected that the spontaneous combustion of coal can be affected from a thermodynamic perspective. However, ionic liquids with different thermal stabilities have distinct influences on coal combustion. Here, the thermal stability of long-flame coal in the presence of five pure ionic liquids ([Bmim][BF4], [Bmim][Ac], [Bmim][NO3], [Hoemim][BF4], and [Pmim][BF4]) was analyzed by thermogravimetric analysis, and the flammability of the raw coal, pure ionic liquids, and coal–IL mixtures (mass ratio of 1:1) were tested using a cone calorimeter according to the indexes of the time to ignition (TTI), mass loss rate (MLR), heat release rate (HRR), total heat release rate (THR), specific extinction area (SEA), and CO production. It is shown that the TTIs of mixtures containing coal-[Bmim][BF4], coal-[Hoemim][BF4], and coal-[Pmim][BF4] are relatively long, and the MLR, HRR, THR, and SEA values are relatively low, indicating that these fluorine-containing ionic liquids have a better flame-retardant effect than the other two fluorine-free ones, which may be ascribed to their similar role to halogen inhibitors. In addition, the endothermic process of [Bmim][BF4], [Hoemim][BF4], and [Pmim][BF4] can reduce the temperature of the coal surface and delay the ignition time of coal. In contrast, the TTI of coal-[Bmim][NO3] and coal-[Bmim][Ac] mixtures is much shorter than that of coal alone, and the MLR, HRR, and THR values are larger. This may be caused by the poor thermal stability of the two nonfluorine ionic liquids that began to decompose and release heat prior to coal, providing a large amount of heat for the low-temperature oxidation of coal and thus accelerating coal oxidation and combustion. Although the F-containing ionic liquids show the ability to inhibit spontaneous combustion of coal to some extent, their organic cations are potentially combustible and release large amounts of heat, smoke, and CO under high temperatures.

Study on Combustibility of Key Components of LiFePO4/C Battery with prelithiation technology

Prelithiation technology has greatly improved the service life of LiFePO4/C battery, but its influence on the combustibility of the battery is still unclear. In this paper, the combustibility of the key components (positive electrode, negative electrode and separator) of LiFePO4/C battery with prelithiation technology and conventional LiFePO4/C battery are compared, and the differences in combustion parameters(effective combustion heat, total heat release, heat release rate) and smoke parameters(total smoke production, CO yield, CO2 yield, and specific extinction area) between the two types of batteries are analyzed. The results show that the combustibility of the two types of batteries is basically similar, and there is no significant difference. With the decrease of the capacity retention rate, the combustibility and smoke generation of the battery show a downward trend.

Impact of inclusion of graphene oxide nanosheets on polypropylene thermal characteristics

Thermal steadiness and flame-resistant characteristics of PP/GO nanocomposites were explored. Inclusion of graphene oxide nanosheets (GOs) increased thermal steadiness of the nanocomposites by at least 50 °C through nano-confinement of PP connections and restriction of release of gaseous molecules during degradation. Pyrolysis showed that process of the degradation of PP was not changed in the presence of nanofillers and alkenes consisting of carbon particles that were deterioration products. With addition of GOs to PP, cone calorimetry experiments exposed a substantial deviation in ignition under irradiation. In addition, inclusion of GOs reduced PP's rate of combustion owing to the creation of a carbon shielding sheet acting as the heat and mass transfer barrier. Uniformly dispersed GOs shifted the decomposing onset temperature (Tonset) of PP to around 40 °C higher which induced a great melt flow rate in the composites and dramatically changed their fire behavior. Delayed dripping resulted in considerably enhanced heat absorption and reduced time for ignition. As a result of development of a shielding film in combustion, under flaming conditions, the highest thermal discharge level of 78% was accomplished. The most prominent features that made PP to prefer carbon nanoparticles were demonstrated by the well-exfoliated GO nanosheets in the PP matrix which was evidenced by TEM images. Findings of TGA indicated that the GO's addition enhanced the thermal steadiness and PP's char yields. The nanocomposites of PP/GO 5.0 wt% attained UL-94 with a grade of no dripping and grade V-1. Cone calorimeter test results showed that the PP's burning performance, peak heat release rate (PHRR) and average specific extinction area decreased noticeably when the GOs' combination effects was intervened. PHRR showed a decrease of 46% compared to the neat PP for the PP/GO 5.0 wt% nanocomposite. This role offered a new modified approach to enhance the GO's flame-resistant effectiveness.

Pyrolysis and combustion characteristics of boric acid and borax treated decorative bamboo filaments

A cone calorimeter and thermogravimetric analysis were used in this work to determine the combustion and pyrolysis characteristics of decorative bamboo filaments before and after being treated with boric acid and borax (1:1) flame-retardants. The kinetics were calculated using the Coates-Redfern model. The results showed that in comparison to the control sample, the flame combustion time decreased from 52 s to 40 s, and the peak value of the heat release rate (PKHRR) and total heat release (THR) of the boric acid and borax treated samples were significantly decreased, by 21.0% and 22.2%, respectively. The peak value of the smoke release rate (PKSPR), total smoke production (TSP), and the specific extinction area (ASEA) were reduced substantially, by 90.6%, 93.3%, and 93.0%, respectively. After the boric acid and borax (1 to 1 ratio) flame retardant treatment, the pyrolysis range, the mass loss, the maximum mass loss rate, and the corresponding peak temperature of the samples all significantly decreased with the same heating rate. The activation energy of the BB-treated samples was higher than the control group, which indicated the boric acid and borax flame retardant had flame retardant efficiency.

Fire reaction properties of polystyrene-based composites using hollow silica as synergistic agent

Hollow silica microsphere (h-SiO2) has been widely applied in the field of thermal insulation, catalyst supports and drug storage/delivery containers. In this research, h-SiO2 has been innovatively used as synergistic agent to enhance the flame retardancy of intumescent flame-retardant polystyrene. The synergistic effects of h-SiO2 on intumescent flame-retardant polystyrene have been studied by limiting oxygen index (LOI), UL-94 test and cone calorimeter test (CCT). When 0.5 mass% h-SiO2 was substituted for the intumescent flame-retardant additive, the LOI of polystyrene composite (PS/IFR/Si0.5) increased by 5 units and the composite preserved the V-0 rating. Manipulation of parameters from CCT indicated that the peak heat release rate was reduced by 27% for the PS/IFR/Si0.5 composite, whereas the total heat release decreased by 14.5% and the ratio of residue increased by 85.6% (from 13.2 to 24.5%) compared to those of the composite without h-SiO2. The synergistic effects of h-SiO2 on intumescent flame-retardant polystyrene are attributed to physical and chemical processes in the condensed phase. The morphologies of charred layer after CCT proved that h-SiO2 induced compact charred layer with enhanced thermal and gas barrier effect, which in turn protected the inner matrix from combustion and decreased specific extinction area by 24.2%.

Deposition growth of Zr-based MOFs on cerium phenylphosphonate lamella towards enhanced thermal stability and fire safety of polycarbonate

The fabrication of engineering plastics combining high efficiency flame retardancy and thermal resistance are essential for practical applications. A novel halogen-free binary hybrid with lamellar and porous structure, Zr-BDC@CeHPP, was created by hydrothermal reaction, thereafter blended with polycarbonate (PC) to improve its thermostability and fire safety. With 2 wt% Zr-BDC@CeHPP, temperatures under peak decomposition rates (Tmax1 and Tmax2) of PC were increased by 28 and 34 °C under oxidizing atmosphere. Time to reach PHRR (t-PHRR) and time to ignition (TTI) and of PC were effectively prolonged to 145 and 18 s, respectively. In comparison with pure PC, the peak of heat release rate (PHRR), total heat release (THR), peak specific extinction area (PSEA) and total smoke release (TSR) of PC composites were reduced by 45%, 20%, 74% and 18%, respectively. Moreover, the flame retardant PC reached V-0 rating in UL-94 vertical burning test. The results indicated that the hybrid was able to fully utilize the advantages of Zr-BDC and CeHPP. In the ignition and middle periods of combustion, Zr-BDC@CeHPP played roles in delaying and suppressing explosive combustion. In severe combustion stage, Zr-BDC@CeHPP could catalyze the char-forming process and serve as a barrier.

Fireproof performance of the intumescent fire retardant coatings with layered double hydroxides additives

MgAlCO3-layered double hydroxides (LDHs) and CaAlCO3-LDHs were respectively added as a synergistic agent to intumescent fire retardant (IFR) coatings. The 2.4 wt% of MgAlCO3-LDHs and the 6.7 wt% of CaAlCO3-LDHs were found to possess the best thermal insulation according to the fire performance tests. Further characterization by a cone calorimeter shows that the MgAlCO3-LDHs are superior to decreasing the specific extinction area of IFR coating, and the CaAlCO3-LDHs are advantageous in some other properties such as heat release rate, effective heat combustion and total heat release. Moreover, the X-ray diffraction (XRD) results infer that the flame retardant of char layer is primarily dependent on the amorphous structure formed after exposure to fire, the X-ray photoelectron spectroscopy (XPS) measurements of O1s, C1s, P2p and N1s reveal that the LDHs fillers suppress the oxidation of the IFR coating, and the Fourier transform infrared spectroscopy (FTIR) tests demonstrate that the LDHs protect the bridge frame structures. It is concluded that the LDHs can prevent the degradation and improve the thermal insulation of IFR coatings.

Thermal stability and flame retardance of EVA containing DNA-modified clays

In this paper, two natural clays (namely, Sodium Cloisite and Sepiolite) were modified with low MW DNA from herring sperm and compounded in EVA copolymer (19 % of vinyl acetate) at 10 wt.% loading, using an internal mixer. The effect of the presence of the biomacromolecule-modified fillers on the thermal properties and on the flame retardance of the resulting composites was thoroughly investigated. In particular, thermogravimetric analyses showed that the presence of the DNA-modified filler enhanced the thermal and thermo-oxidative stability of the polymer matrix. Despite a very limited effect on flammability, cone calorimetry tests revealed that the DNA-modified nanofillers were able to significantly decrease the heat release rate, the peak of heat release rate, the total smoke production, and the specific extinction area. Finally, the presence of the modified nanofillers was responsible for the increase of stiffness, as well as for a certain decrease of ductility of the polymer matrix, as assessed by tensile tests.

Montmorillonite-Synergized Water-Based Intumescent Flame Retardant Coating for Plywood

In this study, montmorillonite (MMT) was used as an inorganic synergist to prepare the water-based intumescent flame retardant (IFR) ornamental coating for plywood. Results indicate that the 7 wt.% MMT modified IFR coating (No. 3) possess the best fire resistance (longer than 20 min) of the tested samples according to the fire performance, which significantly declines the specific extinction area by 44.12 m2·kg−1 compared to the coating without MMT by cone calorimeter. In addition, characterizations such as XPS, XRD, TG, SEM and FTIR were characterized to investigate the surface and bulk properties as well as the morphology of MMT synergized water-based IFR coating. It is revealed that the residual nitrogenous polyaromatic structure and 25.5% residual mass in the No. 3 coating are a result of the effect of MMT on the antioxidation properties of the char layer.

Effect of Thickness on Flammability and Fire Performance of Natural Wood Under Incident Heat Flux by Pilot Ignition

In order to study the influence of natural wood thickness on the flammability and fire performance, an experimental studies of fire parameters under external constant heat flux by piloted ignition of wood timber with different thicknesses (8, 10, 13, 15 mm) were conducted using cone calorimeter approach, by testing procedure prescribed in accordance with international organization for standardization. These parameters include: ignitibility, heat release rate, effective heat of combustion, total heat release, mass loss rate, smoke specific extinction area, and the yield of carbon monoxide. Four species of wood timber, namely pine, maple, oak, and walnut, were exposed horizontally under external heat flux 50 kW/m2. Thermal degradation effects of various species were observed. The obtainable data will be reported to develop a distinct national building code in Jordan and to select the suitable materials for designing of fire safety in buildings of different uses. A good compatible agreement between calculated and experimented results has been obtained. The results indicated that total heat release rate increase with increase thickness of specimen. It is observed that, the time to ignition is very small (around 12 seconds) for all species whatever the thickness is. Heat release rate for the different types of specimens with different thicknesses have been presented. Results show as the thickness of oak specimen increased: 8 mm, 10 mm, 13 mm and 15 mm, the corresponding mass loss depletions are 43%, 34%, 25%, and 21%, respectively.

Non-Chloride in Situ Preparation of Nano-Cuprous Oxide and Its Effect on Heat Resistance and Combustion Properties of Calcium Alginate.

With Cu2+ complexes as precursors, nano-cuprous oxide was prepared on a sodium alginate template excluded of Cl− and based on which the calcium alginate/nano-cuprous oxide hybrid materials were prepared by a Ca2+ crosslinking and freeze-drying process. The thermal degradation and combustion behavior of the materials were studied by related characterization techniques using pure calcium alginate as a comparison. The results show that the weight loss rate, heat release rate, peak heat release rate, total heat release rate and specific extinction area of the hybrid materials were remarkably lower than pure calcium alginate, and the flame-retardant performance was significantly improved. The experimental data indicates that nano-cuprous oxide formed a dense protective layer of copper oxide, calcium carbonate and carbon by lowering the initial degradation temperature of the polysaccharide chain during thermal degradation and catalytically dehydrating to char in the combustion process, and thereby can isolate combustible gases, increase carbon residual rates, and notably reduce heat release and smoke evacuation.

Synthesis of decorated graphene with P, N-containing compounds and its flame retardancy and smoke suppression effects on polylactic acid

Functionalized graphene (PNFR@RGO) has been fabricated by decorating chemically reduced graphene oxide (RGO) with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and branched polyethylenimine (BPEI) in this work. PNFR@RGO is then used to reduce the flammability of polylactic acid (PLA) via a melt compounding protocol. X-ray photoelectron spectroscopy (XPS) and Infrared spectroscopy (IR) have confirmed the successful fabrication of the target PNFR@RGO. The chemical decoration introduces phosphorus and nitrogen elements to the GO which can combine the formation of compact char barriers from graphene nanosheets and the elimination of free radicals when ignited or heated. The results show that the degradation temperature in air is increased and the heat release rate (HRR) is reduced. With the addition of 4 wt% PNFR@RGO, the average specific extinction area (ASEA) and the total smoke release (TSR) of PLA are noticeably suppressed by 92% and 79%, respectively. This is attributed to the combination of the corridor barrier functions of RGO and the radical-scavenging effects of PNFR.