Fire Properties Research Articles

A multiscale model for wood combustion

AbstractUnderstanding wood combustion has become increasingly critical as fire safety engineering moves toward a performance‐based approach to building design. Although different kinetic models have been developed for wood burning, chemical kinetics remains a significant challenge for accurate prediction. This work has developed a novel multiscale model by implementing kinetic parameters calculated from molecular dynamics simulations using reactive forcefield into a kinetic model of wood burning. The calculated kinetic parameters of the main components in wood, namely, cellulose, hemicellulose, and lignin, are first utilized to model microscale thermogravimetric experiments for validation. Subsequently, the mesoscale and full‐scale fire tests have been simulated by the multiscale model. Furthermore, the fire properties of various wood species at different heat fluxes have been predicted and compared with results from the cone calorimeter test. Our multiscale model outperforms existing kinetic models in predicting wood combustion and can effectively discern the influence of chemical components on fire properties.

Flame Retardancy of Short Flax Fibers Modified by Radiation-Induced Grafting of Phosphonated Monomers: Comparison between Pre- and Simultaneous Irradiation Grafting.

Short flax fibers have been modified by radiation-induced grafting using methacrylate monomers containing phosphorus to give them a flame-retardant character. Two methodologies, namely pre-irradiation and simultaneous irradiation grafting, were examined. Certain parameters, notably the dose and the irradiation source (e-Beam and γ rays), were evaluated. The grafting efficiency, in terms of phosphorus content (mass percentage), was measured by X-ray fluorescence spectrometry (XRF). Using simultaneous irradiation, 2.39 wt% phosphorus could be obtained from 10 kGy, compared to 100 kGy in pre-irradiation. Furthermore, for similar phosphorus levels, the location of the grafted polymer chains was different for the two methodologies. The effect of phosphorus content on thermal properties and fire behavior was evaluated on a microscopic scale using a pyrolytic flow combustion calorimeter (PCFC) and on a laboratory scale using a cone calorimeter. It was then pointed out that flammability was linked to the phosphorus content and likely its location, which is associated with the radiation-induced grafting methodology, showing that the grafting conditions influence the final fire properties. Simultaneous irradiation, thus, proved to be more interesting in terms of efficiency and final properties.

Thermal insulation and flammability of composite waste polyurethane foam encapsulated in geopolymer for sustainable building envelope

Polyurethane foam (PUR) is a lightweight, thermally insulating, widely used, and highly flammable material that has after its use an adverse effect on the environment, i.e., PUR disposal is considered hazardous. Its flammability can be mitigated using various fire retardants, but they do not change the hazardous nature of waste PUR. Therefore, in the current study, waste PUR with and without flame retardants based on N and P was incorporated into a geopolymer, the alkali-activated material (AAM) based solely on metakaolin, to evaluate the potential recycling route of waste PUR while taking into account its flammability, so it can enter safely into the circular economy through the building industry. To enhance the mechanical properties of the composite, a fresh mixture was irradiated with microwaves. However, the irradiation of geopolymer containing PUR negatively influenced mechanical performance, which led to the evaluation of the behaviour of the complex dielectric constant of PUR and fire retardants. Materials and composites were evaluated regarding their chemistry, mineralogy, microstructure, and porosity to connect the structure with extrinsic properties like geometrical density, thermal conductivity, and fire properties. Nonetheless, positive influences of PUR being encapsulated in the geopolymer were lowered density (from 1.8 to 1.6 kg/l) and improved thermal insulation ability (from 940 to 860 mW/(m·K)) of the composites: with the inclusion of <5 % of PUR, thermal insulation improved by nearly 10 %. However, the contribution of PUR to the composite originated from its skeleton, which has more than 15 times bigger geometrical density (0.81 kg/l) compared to the density of the skeleton (0.047 kg/l). This offers an open field for further advancements of thermal properties, but would also lead to a decrease of the compressive strength, which was already lowered from 90 MPa for 30 % with <5 % of added grated PUR. Furthermore, the flammable nature of PUR and its other drawbacks can be controlled by permanent embedding in the noncombustible structure of geopolymer, making the envelope of sustainable buildings green and safer. Overall, including grated waste PUR in geopolymer represents a promising, easy, cost-effective recycling path with low energy consumption, where the composite cannot develop fire on a scale of pure PUR, even in the worst-case scenario, but only if the composite is designed in a way, that flammable materials cannot join flames during their combustion. This paper gives prospects to other flammable waste materials to be safely used in the circular economy, and to porous materials to shape properties of the composite by their intrinsic and/or extrinsic properties.

Mechanical and ballistic performance of ramie fiber-reinforced polymer composites: A review

Natural fiber composites (NFCs) have seen an increased innovation and research activities due to their strength, environmental impact, and low cost. NFCs are used in aerospace, construction, leisure, packing, sport, and automotive industries. One such NFC, ramie fiber-reinforced composite has gained more importance due to its high mechanical strength, stiffness, and easy availability to all other natural fibers. In this review, an insight of the research works focusing on ramie fiber, and its reinforced polymer composite has been summarized. Factors such as fiber content, surface treatment, manufacturing techniques, and coupling agents influencing the mechanical properties (tensile, flexural, and impact) have been summarized. It is evident that the surface modification of ramie fiber through chemical treatment and the addition of coupling agents directly impact the mechanical properties of the composite. Furthermore, the usage of ramie fiber composite is still inadequate due to its poor fire and moisture-resistant properties.

Effects of sepiolite addition to acrylic-latex paint on pull-off adhesion strength in nanosilver-impregnated and thermally-modified beech (Fagus orientalis L.) wood

Sepiolite is a silicate mineral that improves the fire properties in solid wood when mixed with a water-based coating. The present study was carried out to investigate and evaluate the effects of sepiolite addition to acrylic-latex paint on the pull-off adhesion strength, as an important characteristic of paints and finishes used in the modern furniture industry and historical furniture as well for preservation and restoration of heritage objects. Sepiolite was added at the rate of 10%, and brushed onto plain-sawn beech (Fagus orientalis L.) wood specimens, unimpregnated and impregnated with a 400 ppm silver nano-suspension, which were further thermally modified at 185 °C for 4 h. The results showed that thermal modification had a decreasing effect on the pull-off adhesion strength, primarily as a result of the thermal degradation of cell-wall polymers (mostly hemicelluloses). Still, a decreased wettability as a result of condensation and plasticization of lignin was also partially influential. Based on the obtained results,thermal modification was found to have a significant influence on pull-off adhesion strength. Sepiolite addition had a decreasing effectin all treatments, though the effect was not statistically significant in all treatments. The maximum and minimum decreases due to sepiolite addition were observed in the unimpregnated control (21%) and the thermally-modified NS-impregnated (4%) specimens. Other aspects of the sepiolite addition, and further studies that cover different types of paints and coatings, should be evaluated before coming to a final firm conclusion in this regard.

Synthesis of FePP@MoS2@Ni‐MOF composites for improving thermal and flame retardant safety properties of polyurea

AbstractPolyurea (PUA) is widely used as a coating in construction, tunnels, bridges, and other fields because of its excellent performance. However, its combustion emits toxic gases and smoke, hindering escape and posing potential fatality risks. Enhancing the flame retardancy of PUA is crucial for safety and expanding its applications. The synthesis of two‐dimensional FePP nanosheets was reported in this paper, employing the solvothermal method, followed by the sequential growth of MoS2 and Ni‐MOF to establish a multilayer composite structure. The elemental composition and morphology of the synthesized FePP@MoS2@Ni‐MOF flame retardants were characterized and analyzed. The flame retardant properties of polyurea composites with varying amounts of FePP@MoS2@Ni‐MOF were investigated using Cone calorimeter tests. The results showed that the prepared flame retardant had good thermal stability and significantly improved fire safety properties. The PUA/FePP@MoS2@Ni‐MOF 3.0 composite exhibited notable improvements compared to pure PUA. Specifically, the peak heat release rate, total heat release rate and peak smoke production rate were reduced by 39.76%, 29.33% and 17.86%, respectively, while total smoke production and total CO production (COP) were reduced by 21.30% and 54.47%. This study provides new insights and experimental basis for the technological development of novel flame retardant coating materials.

Charcoal analysis for temperature reconstruction with infrared spectroscopy

The duration and maximum combustion temperature of vegetation fires are important fire properties with implications for ecology, hydrology, hazard potential, and many other processes. Directly measuring maximum combustion temperature during vegetation fires is difficult. However, chemical transformations associated with temperature are reflected in the chemical properties of charcoals (a by-product of fire). Therefore, charcoal could be used indirectly to determine the maximum combustion temperature of vegetation fires with application to palaeoecological charcoal records. To evaluate the reliability of charcoal chemistry as an indicator of maximum combustion temperature, we studied the chemical properties of charcoal formed through two laboratory methods at measured temperatures. Using a muffle furnace, we generated charcoal from the woody material of ten different tree and shrub species at seven distinct peak temperatures (from 200°C to 800°C in 100°C increments). Additionally, we simulated more natural combustion conditions by burning woody material and leaves of four tree species in a combustion facility instrumented with thermocouples, including thermocouples inside and outside of tree branches. Charcoal samples generated in these controlled settings were analyzed using Fourier Transform Infrared (FTIR) spectroscopy to characterize their chemical properties. The Modern Analogue Technique (MAT) was employed on FTIR spectra of muffle furnace charcoal to assess the accuracy of inferring maximum pyrolysis temperature. The MAT model temperature matching accuracy improved from 46% for all analogues to 81% when including ±100°C. Furthermore, we used MAT to compare charcoal created in the combustion facility with muffle furnace charcoal. Our findings indicate that the spectra of charcoals generated in a combustion facility can be accurately matched with muffle furnace-created charcoals of similar temperatures using MAT, and the accuracy improved when comparing the maximum pyrolysis temperature from muffle furnace charcoal with the maximum inner temperature of the combustion facility charcoal. This suggests that charcoal produced in a muffle furnace may be representative of the inner maximum temperatures for vegetation fire-produced charcoals.

High temperature and fire properties of sustainable syntactic foam reinforced by end‐of‐life tyre‐derived rubber particles

AbstractThe management of end‐of‐life tyres faces challenges due to insufficient recycling infrastructure and technologies, as well as limited markets for the materials recovered from them. To mitigate this, waste rubber can be upcycled and used as filler material for polymer matrix composites. Before rubber‐reinforced composites can be certified for fire‐prone applications, their thermal and flammability properties must be understood. This research investigates the effect of rubber fillers on the thermal stability, flammability and flame spread characteristics of epoxy matrix syntactic foam. Thermogravimetric analysis, Fourier Transform Infrared spectrometry (FTIR), scanning electron microscopy and attenuated total reflection FTIR spectrometry were employed to elucidate changes in thermal degradation behaviours. The influence of rubber fillers on the flammability of syntactic foam was assessed using the cone calorimeter. The fire reaction properties of rubber‐reinforced foam were affected by the intensity of the incident heat flux. Regardless of the incident heat flux, an increase in rubber content led to higher total heat release. At the lower heat flux of 35 kW/m2, the fire growth rate increased with rubber content, but at the higher heat flux of 50 kW/m2, the fire growth rate decreased as the rubber content increased. Importantly, all rubber‐reinforced syntactic foams achieved a UL94 HB ranking and exhibited reduced flame spread rates compared to the unmodified foam. This study demonstrated the potential for upcycling waste rubber into sustainable engineering products and expanded the knowledge base on fire reaction properties and flame spread characteristics of such hybrid composite materials.

Investigating the efficacy of expanded graphite/NaCl composite powder as an extinguishing agent for metal combustion suppression

Advancements in fire safety technology have led to the development of expanded graphite (EG)/NaCl composite powder, a dry powder fire extinguishing agent specifically for metal fires. This study used custom apparatus to examine the fire suppression properties of this composite powder in relation to its constituent elements, EG and NaCl. Compared to pure EG, this composite powder has a smaller particle size and better thermal stability. The flames of a sodium metal fire were effectively suppressed using only 8 g of the EG/NaCl composite powder. The powder suppressed the flames within 22 s. This performance surpassed that of the use of EG or NaCl alone. Moreover, after the fire was extinguished, the temperature decreased at a rate of 1.23 °C/s within the temperature range of 350–250 °C. This rate was 15.44% and 44.78% faster than those of EG and NaCl, respectively. The suppressive effects of the EG/NaCl composite powder are primarily attributed to heat absorption—which prevents contact between combustible metals and air—and the adsorption of depleting H∙ and OH∙ radicals. These results indicate that EG/NaCl composite powder has promising firefighting applications, particularly in fires involving the burning of metals.

Effect of Applied Pressure on the Performance of Biodegradable Fiber Insulation Board Manufactured from Camphor Branches (Cinnamomum camphora)

Currently, the predominant thermal insulation materials in the construction industry are primarily derived from inorganic sources. While these materials demonstrate commendable thermal insulation capabilities, their widespread use raises significant environmental concerns. The utilization of wood fiber materials presents a promising solution to mitigate these drawbacks. This study focuses on the fabrication of biodegradable fiber insulation board (BFIB) using camphor branches. The manufacturing process avoids the use of chemical additives, employing a physical method that utilizes hot pressing and relies on the formation of intermolecular hydrogen and hydroxide bonds between the fibers. The study evaluates the influence of applied pressure on the properties of BFIB. SEM images reveal that, with an increase in applied pressure, the fibers exhibit a more regular pattern, subsequently enhancing the mechanical properties, hygric behavior, and fire resistance properties of BFIB. As an environmentally friendly and renewable material, BFIB holds the potential to substitute conventional insulation materials. It is particularly intriguing for energy-saving purposes when applied as building insulation for walls or ceilings.

Preparation and properties of gradient fire & corrosion protection magnesium phosphate cement coatings

Fire and corrosion protection are the main problems limiting the application of steel. Gradient fire & corrosion protection coating for steel structures was prepared by magnesium phosphate cement (MPC) with high bond strength, excellent anti-corrosion, and high-temperature resistance. The interface inside the MPC coating and of the MPC coating and steel plate were observed. The bonding strength, corrosion, and fire performance of MPC coating were investigated before and after dry-wet cycles. The results showed MPC had high bond strength with itself even under dry-wet cycle conditions. Only 6 mm MPC coating can meet the fire and corrosion resistance of steel structures. When the total thickness of MPC coating was 6 mm, the rising thickness (0–1.6 mm) of MPC paste improved the bond strength to 2.5 times and anticorrosive performance but reduced the fireproof performance of MPC coating. Even though the thickness of the MPC paste was 1.6 mm, the fireproof performance of MPC coating remained abundant. After 28 dry-wet cycles, the fireproof performance of MPC coating with 0.4 mm MPC paste was comparable to that before the dry-wet cycle. The bond strength was still more than 0.3 MPa, which can still meet the requirements of the specification.

Fire Performance of Endospermum malaccense Cross Laminated Timber (CLT) Treated with Fire Retardant

This study assessed the fire performance of cross-laminated timber (CLT) made from sesenduk (Endospermum malaccense) painted with a fire retardant. Teknoksafe 2407 (Tk-Exterior) and Teknoksafe 2457 (Tk Interior) fire retardants were prepared and applied to the sesenduk CLT. Fire properties such as surface spread of flame test, charring rate test, fire resistance test, and chemical property changes before and after fire testing were evaluated and compared to Control CLT. The results showed that using fire retardant effectively prevented the fire from spreading.

Fire retardants giving special properties to fibers and textile materials based on them

The fire-retardant properties of modified polyacrylonitrile fibers with phosphorus-containing polymers, as well as nitrogen and brominecontaining flame retardants, have been studied. It has been shown that, in contrast to low molecular weight fire retardants, polymer and oligomer fire retardants give fibers higher fire-retardant properties. The results of determining the flammability of samples showed that the treatment of polyacrylonitrile fibers with oligomeric flame retardants based on the developed flame retardants improves the fire-retardant properties of fibers and materials based on them. As a result of comprehensive research, it was established that for the manufacture of fire-resistant material it is advisable to use the optimal ratio of “polyacrylonitrile fiber - fire retardant”. Carrying out fire-retardant treatment of polyacrylonitrile material with compositions of 3-chloro-1,2-hydroxypropane with 2,4,6-triamino-1,3,5-triazine makes it possible to obtain fabrics with a reduced fire hazard and with the required strength parameters. Also, in the work, based on kinetic and spectroscopic studies and taking into account literature data, a mechanism of oligomeric fire retardant is proposed, which gives fibers and textile materials special fire resistance properties.

Экспериментальное определение давления насыщенного пара жидких моторных топлив

Purpose. Currently, new brands of liquid motor fuel are produced, whose fire hazardous properties are not reflected in regulatory documents and reference literature. The values of saturated vapour pressure of petroleum products presented in them differ significantly from each other and that may affect the results of assessing fire and explosion hazard of the facility under protection. The article provides the results of experimental evaluation of motor gasolines and diesel fuel saturated vapour pressure. Methods. Analytical and experimental methods for determining saturated vapour pressure of motor gasolines and diesel fuel have been used during the research process. Findings. The saturated vapour pressures of motor gasoline and diesel fuel of different brands have been determined experimentally. It has been found that saturated vapour pressure of petroleum products is different and varies over a wide range. Research application field. Experimental studies allowed obtaining the numerical value of saturated vapour pressure of currently marketed brands of liquid motor fuel. Conclusions. During the experiments, the values of the saturated vapour pressure of liquid motor fuels, significantly different from those given in the regulatory documents or determined by calculation have been obtained. The application of the obtained results will make it possible to assess fire and explosion hazard of storing flammable liquids in tank farms of the facilities under protection.

The Strength and Fire Properties of Paper Sheets Made of Phosphorylated Cellulose Fibers.

Phosphorylated cellulose can be an intrinsic flame retardant and a promising alternative for halogenated fire inhibitors. In this study, the mixture of di-ammonium hydrogen phosphate (DAP) and urea (U), containing phosphate and nitrogen groups, was applied to attain fire inhibitor properties. Functional groups of cellulose were grafted with phosphorous by keeping the constant molar ratio of 1/1.2/4.9 between anhydroglucose units of cellulose/DAP/U in different concentrations of bleached kraft pulp. Phosphorus concentrations were determined using the ICP hrOES method, and paper sheets were made using the Rapid Köthen apparatus. The tensile strength of phosphorylated cellulose increased twice compared with unmodified cellulose when the phosphorous concentration increased to 10,000 g/kg. An increase in the tensile index comes from the higher freeness of pulp and cross-linking of the phosphorous group between cellulose fibers. Remarkable fire retardancy effects were achieved in cellulose concentrations above 5 wt%. The raised phosphorous concentration above 10,000 g/kg due to the phosphorylation process caused the formation of a char layer on a cellulose surface and the nonflammable gas emission. That effect was indirectly confirmed by reducing the combustion temperature and HRR by 50 and 45%, respectively. Due to increasing phosphorus concentration in cellulose sheets, cellulose's fire and strength properties increased significantly.

A comprehensive study on the fire resistance properties of ultra-fine ceramic waste-filled high alkaline white cement paste composites for progressing towards sustainability

The most practical sustainable development options to safeguard the local ecology involve reducing the use of raw materials and guaranteeing proper recycling of the principal destroyed solid wastes. Preventing the creation of hazardous waste and the subsequent pollution that results from improper disposal is a top priority. Based on this, the study's authors recommend reusing the ultra-fine ceramic shards (CW). High-alkaline white cement (WC) has been partially replaced by ultra-fine CW because it is a cheaper, more abundant, and more lasting environmental material used in the production of trendy blended white cement pastes composites. In this context, we look at ultra-fine CW, a material that has been suggested for use as a hydraulic filler due to its high performance, physicomechanical qualities, and durability. XRF, XRD, FTIR, and SEM measurements are used to characterize the microstructure, thermal characteristics, and thermodynamics. Because of the effect of ultra-fine ceramic waste, the firing test reduces the mechanical strength by default, but with active filler, decreases slowly and increase its physicomechanical features and compressive strength compared to the control sample (WC), setting a new benchmark. The maximum amount of crystallization formed in the presence of ultra-fine ceramic waste in WC-matrix, resulting in a decrease in total porosity and early cracking. Together, the improved workability and energy-saving features of cement blends with ultra-fine ceramic waste, reflect their economic and environmental benefits, which may reduce building costs and boost the durability of the raw materials used in the mix.

Radiative characteristics of large-scale fire whirl: An experimental study

Flame radiative characteristics, depending on the flame type, flame scale, and fuel type, are key parameters that determine fire spread and thermal hazards. Accurate prediction of flame radiation in large-scale natural fires requires detailed information on radiative characteristics. This paper presented an experimental study on the radiative properties of large-scale fire whirls with RP-5 aviation fuel. The maximum flame height and mean width reached 21.40 m and 3.60 m, respectively. Unlike large-scale free pool fires, the radial stabilization effect of the fire whirl suppressed the unstable toroidal vortex structures and the smoke production significantly. Most of the flame was high-temperature and high-emissive power areas in the large-scale fire whirl, and the emissive power exceeded 100 kW/m2 on about 60 % flame area. The flame temperature and emissive power first increased with height, then stabilized and decreased in the upper part of the fire whirl. The peak flame temperature, mean flame temperature, and mean emissive power all increased with an increase in the flame width. The mean emissive power ranged from 93.06 to 157.47 kW/m2, 2.3–3.9 times the values in free pool fires of the same scale. The solid flame radiation model could effectively predict the instantaneous radiative heat fluxes from large-scale fire whirls to distant external targets with the corrections of atmospheric transmissivity. The semi-empirical correlation of the radiative fraction based on the turbulent dissipation showed that neither the flame size nor heat release rate affects the radiative fraction, consistent with the our and other researchers’ experimental data from medium to large-scale fire whirls.

Facile construction strategy for intrinsically fire-safe and thermal-insulating bio-based chitosan aerogel

Bio-based aerogels have become a research hotspot in the emerging fields because of their remarkable biocompatibility, degradability and light weight, but their low strength and flammability limits their further application. In this study, chitosan (CS) containing flame retardant element was selected as the matrix, and a lightweight, flame retardant and thermal insulating CS aerogel was successfully prepared by the ion exchange between methylphosphonic acid (MPA) and acetic acid (HAc), and directional freeze-drying technology. The compressive strength and elastic modulus of CS@MPA aerogel were 15.2% and 8.5% higher than that of CS@HAc aerogel due to the 3D cross-linking structure between MPA and CS. Compared with CS@HAc aerogel, CA@MPA1.1 aerogel demonstrated excellent thermal insulating properties, and its thermal conductivity (25.46 mW/mK) was significantly lower than that of air (26.7 mW/mK). The introduction of MPA promoted the degradation and charring of CA@MPA aerogel, and the formation of high quality char layer efficiently exerted the barrier effect. Meanwhile, the phosphorus oxygen radicals and inert gases from the decomposition of CS@MPA aerogels effectively decreased the combustion intensity in gas phase. Therefore, the PHRR and THR of CS@MPA1.1 aerogels were decreased by 91.7% and 69.5% compared to CS@HAc aerogels. In summary, CS@MPA aerogel not only conforms to the current concept of sustainable development, but also possessed excellent thermal insulation, mechanical, and fire safety properties. It is expected to replace the traditional petrochemical-based materials, and shows broad application prospects in the fields of building insulation and energy storage.

Development of super dimensional stable poplar structure with fire and mildew resistance by delignification/densification of wood with highly aligned cellulose molecules

Wood is one of the most popular materials for construction purposes because of its environmentally friendly and sustainable characteristics. However, the use of wood is constrained by the lengthy time it takes for trees to mature. Consequently, fast-growing wood species have become popular as substitute options due to their ability to rapidly reach maturity and high yields. Although the problem of low density and strength has been effectively addressed in recent years by densifying wood, the problem of large thickness swelling due to moisture and water absorption has limited its application. Therefore, we reported an effective modification strategy to overcome the thickness swelling issue of densified wood by preparing a cellulosic reinforced material through the synergistic action of alkaline chemical pretreatment, multi-step cyclic impregnation and high-temperature densification. The results showed that the alkaline chemical pretreatment was effective for removing a large amount of lignin and hemicelluloses, creating a large number of hydrogen bonds among the remaining strong celluloses. The impregnated sodium silicate solution bonded celluloses tightly, and the densification treatment contributed to the production of Si-O-Si structure, forming the shuttle hybridized structure through Si-O-C bonds. The hardness, flexural strength, elastic modulus, and compressive strength of the modified wood increased by 3.9, 6.0, 3.4 and 28.2 times, respectively. In addition, 0 % thickness swelling for 30-day moisture absorption and 1.0 % thickness swelling for 72-hour water absorption were achieved, realizing super dimensional-stable poplar structures. Furthermore, the high-performance densified wood prepared by this method has excellent fire and mildew resistance properties, which lays the foundation for the application of fast-growing wood in outdoor engineering structures.

Effect of Borax-Boric Acid Treatment on Fire Resistance, Thermal Stability, Acoustic, and Mechanical Properties of Mycelium Bio Composites

Mycelium biocomposite materials have been established as a sustainable alternative to polystyrene in single use applications like packaging. However only little investigations are done on improving their resistance to fire and heat, which can find use in newer applications. This paper focuses on the development and characterization of a mycelium-based sawdust-coir pith biocomposite material treated with a combination of fire-retardant compounds (borax and boric acid). The outcomes of fire resistance tests, such as flammability, flame penetration and rate of burning demonstrated a significant improvement in values with respect to untreated samples. However, samples having 30% boron compounds by weight in it exhibited the best fire resistance properties. The thermal analysis of treated samples indicated that the presence of fire-retardant chemicals has not significantly affected their thermal stability. The glass transition temperature (Tg) of treated mycelium composite material was found to be 212.75 °C against a value of 207.78 °C for untreated samples. The fire retardant treated mycelium composite samples having 30% boron by weight in it, exhibited an average sound absorption coefficient of 0.38 compared with a sound absorption coefficient of 0.29 for polyurethane foam. The prepared mycelium biocomposite has a self-extinguishing nature and exceptional fire resistance capabilities with an LOI value of 50%. The mechanical testing revealed that the presence of fire-retardant chemicals has significantly improved the flexural properties. However, only a marginal increase was visible in the compression strength of mycelium biocomposites.