Fire Reaction Research Articles

Sustainable insulation panel for buildings made of rice husks and posidonia

The design of the building envelope is crucial to achieve adequate thermal comfort by means of insulating materials that prevent heat flow without excessive energy costs. Generally, materials based on fossil fuel content a large carbon footprint, so when environmental criteria are becoming increasingly important, it is necessary to search for more sustainable insulation materials with a low environmental impact, lower energy use or few CO2 emissions. The aim of this work is focussed on using the agricultural residue or plant debris that sea expels, specifically rice husk and posidonia oceanic leaves. The properties of both materials are studied by experimental tests at different densities to define appropriate thermal conductivity. In addition, acoustic performance, sensitivity to water, durability (mould fungus), mechanical properties and fire reaction are tested to evaluate their behaviour in comparison to other commercial insulation materials. The results highlight the proper performance of rice husks and posidonia as material for insulation panels with 0.055 and 0.045 W/mK of thermal conductivity, respectively. Furthermore, rice husks and posidonia offer a promising reaction to fire with low heat release and smoke production for an element that has been critical in buildings in past catastrophic fires.

Experimental and Numerical Studies on the Fire Performance of Thin Sustainable Wood-Based Laminated Veneers

Wood and wood-based products are abundantly used, especially in structural applications, due to the impetus for sustainable development. The present work helps highlight the fire performance of plywood, one of the most used wood-based laminated structural components, under three different heat fluxes of 35 kW/m2, 50 kW/m2, and 65 kW/m2. The effects on the various fire reaction properties, namely, time to ignition, heat release rate, peak heat release rate, time to peak heat release rate, time to flameout, total burn time, and mass loss, were observed and reported. The times to ignition (42.2% and 35.4%), peak heat release rate (27.7% and 18.9%), flameout (22.2% and 28.6%), burn time (10.6% and 16.1%), and residual mass (25% and 53.3%) were reduced with the increase in heat flux from 35 kW/m2 to 65 kW/m2, respectively, whereas the peak heat release (21.7% and 2.4%) and ignition temperature (6.5% and 6.6%) were observed to increase. The vertical burning test (UL-94) illustrated the plywood samples to have a V-1 rating, with self-extinguishing capabilities. A numerical predictive model has also been developed based on the Fire Dynamics Simulator to predict the time to ignition, time to flameout, and heat release rate trend along with the peak heat release rate—it is shown to have good agreement with the experimental results, with an average correlation coefficient of 0.87.

Keratinous Natural Fibres as Sustainable Flame Retardants and Reinforcements in Polymer Composites

Natural fibres have been used as fibre reinforcements in composites as they offer eco-friendly and economic advantages, but their susceptibility to deterioration when exposed to heat and flames has limited their practical application in fibre-reinforced polymeric composites. Fire-reaction properties have been explored in reasonable detail for plant fibres, but a gap exists in the understanding of animal fibre-reinforced composites. Understanding the thermal and fire reactions of these keratin-rich animal fibres is crucial for material selection and advancing composite product development. The current paper critically discusses the existing research landscape and suggests future research directions. The use of keratinous fibres in composites can definitely improve their thermal stability and fire performance, but it also appears to adversely affect the composite’s mechanical performance. The main part of this paper focuses on the flame-retardant treatment of keratinous fibres and polymer composites, and their behaviour under fire conditions. The final part of this paper includes a brief look at the environmental impact of the treatment methods; the overall processing of keratinous fibre-reinforced composites is also presented to gain further insight.

Assessment of Elaboration and Performance of Rice Husk-Based Thermal Insulation Material for Building Applications

Developing environmentally friendly building materials with low environmental impacts is receiving more attention nowadays to face the global challenges of climate change; building insulation materials made from agricultural waste can be used for their low environmental impact and to generate responsible supplies that utilize natural resources adequately. The study aims to assess a panel made from rice husk using the pulping method. An experimental design established the proportion of rice husk, the percentage of additive (NaOH concentration), boiling time and blending time. Taguchi’s method was applied to investigate the effect on density and thermal conductivity; the final panel with optimum conditions was morphologically analyzed using scanning electron microscopy (SEM); the thermal behavior was studied by thermogravimetric analysis (TGA); fire reaction and smoldering behavior were analyzed; and characterization in water absorption and acoustic absorption performances were established. The results show thermal conductivity values between 0.037 and 0.042 W/mK, a smoldering velocity of 3.40 mm/min, and a good acoustic absorption coefficient in octave frequency bands between 125 Hz and 4 kHz greater than 0.7. These characteristics are competitive with other insulating bio-based materials available on the market. This study employed chemicals utilized by other biomaterials for the pulping process and in flame retardants. However, it is important to investigate natural treatments or those with a diminished environmental impact.

Experimental investigation of conductive heat transfer and fire protection in a polymer-based plate heat exchanger

Polymer-based heat exchangers offer several attractive features for thermal management applications such as low-cost, lightweight, antifouling, and anti-corrosion characteristics. However, their thermal performance is compromised primarily by the low thermal conductivity and high-flammability. This work consists of developing new polymer-based plate heat exchangers, which are made from epoxy resin reinforced by banana fibres and manufactured using the vacuum bag resin transfer moulding technique. The aim of this research is to improve both the heat transfer efficiency and thermal protection. The proposed approach involves incorporating silicon carbide powder as charge into samples to increase their thermal conductivity, and applying an intumescent fire-retardant coating to improve their capacity to withstand heat and flames. To determine the efficacy of this approach, a cone calorimetry test was performed to examine the thermal distribution within the plate heat exchanger samples and to assess fire reaction parameters during a fire scenario. The results revealed a notable increase in thermal conductivity, due to the addition of silicon carbide powder. Furthermore, the intumescent fire-retardant coating substantially improved the samples’ thermal resistance. This result has been verified by thermogravimetric analysis conducted during this work. These findings suggest that using banana fibres-reinforced epoxy resin, combined with silicon carbide powder and intumescent fire-retardant coating, has the potential to enhance the overall thermal performances of plate heat exchangers. The addition of silicon carbide powder increases the thermal conductivity by 36%. This demonstrates the feasibility of utilizing sustainable and biodegradable materials to manufacture heat exchangers that are more efficient and eco-friendly.

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.

Evaluating the fire behaviour of cement-based lightweight materials with textile waste incorporation using a cone calorimeter

The conscientious utilization of natural resources and the efficient waste management have become a matter of great concern in recent years due to the harmful impacts on the environment. The construction sector presents itself as one of the sectors that most contributes to raw materials consumption and waste generation, demanding the investigation of more sustainable and eco-friendly building materials, where the valorisation of wastes originated from other industries can be promising. Following the sustainability concept in construction materials, this work investigates the potential use of textile waste in cement-based lightweight construction material, evaluating the fire reaction of the material using the cone calorimeter equipment. The samples were tested at three different radiant heat fluxes (35 kW/m², 50 kW/m², 75 kW/m²) to simulate different fire situations. For the highest heat flux, the lightweight construction element with textile waste incorporation showed a Heat Release Rate Average ≤ 18 kW/m², a peak Heat Release Rate Average ≤ 60 kW/m², and a Total Heat Release Average ≤ 33 MJ/m². These results reveal a very satisfactory fire behaviour compared to other materials and show the suitability of using textile waste as lightweight cement-based materials.

Enhancement of fire resistance and mechanical performance of polypropylene composites containing cellulose fibres and extracellular biopolymers from wastewater sludge

In the present research, a bio-based flame retardant (FR) was prepared using a biopolymer derived from wastewater sludge to improve the fire performance of polypropylene (PP). Extracellular polymeric substances (EPS), which were extracted from wastewater aerobic granular sludge, were absorbed into cellulose-based fibres, such as flax and toilet papers. Thermogravimetric analysis results indicated that the EPS-cellulose fibres played a significant role in enhancing the char formation of PP composite. Furthermore, the incorporation of the bio-based FR into PP restricted its vertical burning characteristics, and at the same time enhanced the tensile moduli of the composites. The reaction between phosphoric acids from EPS and hydroxyl groups of cellulose fibres improved dehydration and char formation of the composites to enhance the overall fire reaction properties. This study opens up new possibilities for the wastewater-derived biopolymer “EPS” to prepare the bio-inspired FRs for cellulose-based fibres and composites, and enhance sustainability of wastewater sludge treatment.

Physico-mechanical properties of plastic waste-containing gypsum composites exposed to elevated temperature

This study presents the characterization of residual physico-mechanical performance of gypsums incorporating two types of plastic waste (i.e. polypropylene and nylon), after exposure to high temperature (23 °C–300 °C). The bulk density, ultrasonic pulse velocity, young’s modulus and mechanical strength were analysed. Furthermore, the fire reaction performance was evaluated according to standards. Also, an experimental toxicity assessment of gases released during combustion was conducted. As a results, the residual properties of the composites present a higher dependence on the reactions that take place in the gypsum matrix than on plastic waste content. Moreover, plastic-containing composites could be classified as A2 non-combustible material.

Flammability of Thick but Thermally Thin Materials including Bio-Based Materials

The fire reaction of various types of flammable lightweight materials is investigated using a cone calorimeter. The influences of parameters such as sample density, sample mass, effective heat of combustion and heat flux on the mass loss after exposition are discussed. Interpretations of the hemp fibers’ tests results lead us to propose a phenomenological model able to calculate the peak of heat release rate (pHRR) of such thermally thin materials, with or without flame retardant. A database gathering the whole results of tests performed on a large set of materials including fibers, bio-resources panels, bio-based concretes and fabrics is used to validate the proposed model. Interestingly, the model is found to be relevant also for denser wood specimens. The model is based on the distinction of the contributions of the exposed top layer and the deeper layer to the combustion. Indeed, in such materials, the heat conduction is limited (either by the intrinsic properties of the material or by the formation of an insulating char) and therefore the pHRR only depends on a limited volume of materials directly absorbing the heat flux from the radiant cone. Accuracy and limitations of the model are discussed.

Synergistic Effect of Nano-Silica and Intumescent Flame Retardant on the Fire Reaction Properties of Polypropylene Composites.

Silica nanoparticles (nano-silica) were used as synergistic agents with ammonium polyphosphate (APP) and pentaerythritol (PER) to enhance flame retardancy of polypropylene (PP) in this research. The composites were prepared using a melt-mixing method. The influences of nano-silica on the fire performance of composites were thoroughly discussed, which promotes understanding of nano-silica on the flame-retardant performance of polypropylene composite. Scanning electron microscope (SEM) and energy-dispersive spectrometer (EDS) results indicated that the nano-silica with a diameter of about 95 ± 3.9 nm were dispersed favorably in the composite matrix, which might elevate its synergistic effect with intumescent flame retardant and improve the flame retardancy of polypropylene composite. The synergistic effects between nano-silica and intumescent flame retardant on PP composites were studied using the limiting oxygen index (LOI), UL-94 test, and cone calorimeter test (CCT). The total amount of flame retardant was maintained at 30%. When the dosage of nano-silica was 1 wt.%, the LOI value of PP/IFR/Si1.0 composite reached 27.3% and its UL-94 classification reached V-1. Based on the parameters of the CCT, the introduction of nano-silica induced composites with depressed heat release rate (HRR) and peak heat release rate (PHRR). The PHRR of PP/IFR/Si0.5 was only 295.8 kW/m2, which was 17% lower than that of PP/IFR. Moreover, the time to PHRR of PP/IFR/Si0.5 was delayed to 396 s, which was about 36 s later than that without nano-silica. EDS was used to quantitatively analyze the distribution of silica in charred residue. The EDS results indicated that the silica tended to accumulate on the surface during the fire. The surface accumulation characteristic of silica endows it with the enhanced flame-retardant properties of polypropylene composite at a very small dosage (as low as 1 wt.%).

Fire reaction properties of bio‐based aggregates used in thermally insulated building components

AbstractBio‐based aggregates can be seen as one of the promising alternatives to reduce the environmental impacts of buildings due to their lower carbon footprint and energy efficiency. They have great potential to be incorporated into inorganic matrices and produce insulating materials. However, there is a lack of information about the flammability of these materials. This work presents the results of an experimental investigation of the fire behaviour of bio‐based materials. In this study, wastes of bamboo, wood shavings and rice husk were used and were evaluated for their fire performance in the natural state and after treatment in an alkaline solution. The fire reaction properties were determined by using a Mass Loss Cone Calorimeter in order to obtain the parameters of heat release rate (HRR), total heat released (THR), effective heat of combustion (EHC), total mass loss (TML), ignition time (IT) and time of combustion (TC). In addition, physical characterization and thermogravimetric tests were carried out as well as scanning electron microscopy analyses. The results show that the alkaline treatment of the bio‐based aggregates is able to reduce the average HRR and the EHC of all bio‐aggregates but does not delay the ignition of these materials. Among the residues studied, rice husk presented the lowest peaks and averages of HRR, THR, total mass loss, EHC and time to flameout; however, the ignition occurred faster.

Fireproofing flammable composites using mycelium: Investigating the effect of deacetylation on the thermal stability and fire reaction properties of mycelium

This paper presents research findings on the influence of alkaline deacetylation on the thermal stability and fire reaction properties of non-pathogenic Basidiomycota fungi (mycelium) grown in molasses. The relationship between deacetylation conditions, such as incubation time and NaOH concentration, and the thermal and fire reaction properties of mycelium was investigated. The degree of deacetylation was also examined for its influence on the high-temperature thermal stability of mycelium, such as char formation. The findings indicated that the high-temperature thermal stability increased as the degree of deacetylation increased due to the conversion of chitin into chitosan as well as the presence of char-promoting hydroxyl‑terminated polysaccharide moieties. The study further investigated the influence of hollow glass microspheres on the thermal properties and microscale combustion behaviour of unmodified and deacetylated mycelium. This study provides an in-depth analysis of the thermal degradation mechanisms that govern the thermal stability and char-forming ability of unmodified and deacetylated mycelium. Additionally, the link between the thermal stability and fire reaction properties of mycelium and its deacetylated derivatives was established. Finally, the effectiveness of unmodified and deacetylated mycelium mats for fireproofing flammable glass fibre-reinforced epoxy laminates exposed to a simulated moderate-intensity fire was evaluated.

Flammability study of decking sections found at the Wildland–Urban interface at different scales

This work presents a study of the fire reaction of two types of decking sections (wood and thermoplastic) exposed to a radiant heat source. The flammability was studied at two scales: a cone calorimeter was used at product scale (36 cm2) and at assembly scale (around 1300 cm2), experiments were performed under a Large Scale Heat Release calorimeter with a radiant burner. Since the wood decking sections have gaps, the influence of the orientation of the sections facing the burner was further investigated. At product scale, the wood sections ignite sooner than the thermoplastic sections whereas the thermoplastic sections have a higher peak of heat release rate. At assembly scale, the thermoplastic decking sections ignite sooner and have a higher peak of heat release rate than wood decking sections, regardless of the orientation adopted. Wood sections with boards oriented perpendicular to the burner ignite sooner and have a higher peak of heat release rate than those oriented parallel. The fire tests at both scales highlighted the influence of the shape of the products on their ability to ignite. Flame retardant should be included in decking assemblies to decrease the fire risk at WUI.

Effect of fire-retardant coating on bamboo and banana-based biocomposites: A comparative study thermogravimetric analysis and cone calorimeter tests

In this work, a thermal behaviour comparison of a new bamboo-based and banana-based Green Bio-Composites (GBC) is conducted using thermogravimetric analysis (TGA) and cone-calorimeter experiments. An Intumescent Fire-Retardant (IFR) coating (a mixture of Exolit IFR36 and boric acid) has been applied on the investigated GBC materials in order to explore the flammability resistance of such GBCs. Vacuum Bag Resin Transfer Moulding (VBRTM) technique has been used to manufacture the samples. TGA test have been conducted under oxidative atmosphere with three different heating rates while cone calorimeter tests have been performed with a horizontally exposure on the top surface of the sample. The outcomes of TGA revealed that Bamboo-based (BM-GBC) and Banana-based (Bn-GBC) materials exhibited similar thermal degradation patterns. However, BM-GBC outperformed Bn-based in the cone calorimetry analysis, this is proven by the fire reaction parameters as well as the higher char residue. In addition, IFR coating improved the flame retardancy of both GBCs, reduced the Peak Heat Release Rate (PHRR) by approximately 40–50% and smoke production (SEA) by 26%. SEM and EDS analysis of char residue were performed to deeply investigate the effectiveness of the IFR as a protecting layer.

The Components' Roles in Thermal Stability and Flammability of Cork Powder.

In this study, an analysis of the influence of extractives, suberin and lignocellulosic components on the pyrolysis decomposition and fire reaction mechanisms of a cork oak powder from Quercus suber L. is presented. The summative chemical composition of cork powder was determined. Suberin was the main component at 40% of the total weight, followed by 24% of lignin, 19% of polysaccharides and 14% of extractives. The absorbance peaks of cork and its individual components were further analyzed by means of ATR-FTIR spectrometry. Thermogravimetric analysis (TGA) showed that the removal of extractives from cork slightly increased the thermal stability between 200 °C and 300 °C and led to the formation of a more thermally stable residue at the end of the cork decomposition. Moreover, by removing suberin, a shift of the onset decomposition temperature to a lower temperature was noticed, indicating that suberin plays a major role in enhancing the thermal stability of cork. Furthermore, non-polar extractives showed the highest flammability with a peak of heat release rate (pHRR) of 365 W/g analyzed by means of micro-scale combustion calorimetry (MCC). Above 300 °C, the heat release rate (HRR) of suberin was lower than that of polysaccharides or lignin. However, below that temperature it released more flammable gases with a pHRR of 180 W/g, without significant charring ability, contrary to the mentioned components that showed lower HRR due to their prominent condensed mode of action that slowed down the mass and heat transfer processes during the combustion process.

Experimental Study of Thermal and Fire Reaction Properties of Glass Fiber/Bismaleimide Composites for Aeronautic Application.

Thermal behavior and fire reaction properties of aerial glass fiber (GF)/bismaleimide (BMI) composites were tested using thermogravimetric analysis (TGA), thermogravimetric coupled with Fourier transform infrared spectroscopy (TG-FTIR), cone calorimeter, limiting oxygen index, and smoke density chamber. The results showed that the pyrolysis process was one stage in a nitrogen atmosphere with the prominent volatile components of CO2, H2O, CH4, NOx, and SO2. The release of heat and smoke increased with the increase in heat flux, while the time required to reach hazardous conditions decreased. The limiting oxygen index decreased monotonically from 47.8% to 39.0% with increasing experimental temperature. The maximum specific optical density within 20 min in the non-flaming mode was greater than that in the flaming mode. According to the four kinds of fire hazard assessment indicators, the greater the heat flux, the higher the fire hazard, for the contribution of more decomposed components. The calculations of two indices confirmed that the smoke release in the early stage of fire was more negative under flaming mode. This work can provide a comprehensive understanding of the thermal and fire characteristics of GF/BMI composites used for aircraft.

Bio-Based Phosphate-Containing Polyester for Improvement of Fire Reaction in Wooden Particleboard.

A new phosphate-containing bio-polyester based on glycerol and citric acid was synthesized and evaluated as fire-retardant (FR) in wooden particleboards. Phosphorus pentoxide was used to first introduce phosphate esters in the glycerol followed by esterification with citric acid to produce the bio-polyester. The phosphorylated products were characterized by ATR-FTIR, 1H-NMR and TGA-FTIR. After polyester curing, they were grinded and incorporated in laboratory produced particleboards. The fire reaction performance of the boards was evaluated by cone calorimeter. An increased char residue was produced depending on the phosphorus content and the THR (Total Heat Release), PHRR (Peak of Heat Release Rate) and MAHRE (Maximum Average of the Rate of Heat Emission) were considerably reduced in presence of the FRs. Highlights: Phosphate containing bio-polyester as fire retardant in wooden particle board; Fire performance is improved; Bio-polyester acts in the condensed and gas phases; Additive effectiveness similar to ammonium polyphosphate.

Medium-Scale Fire Resistance Testing of Timber Structures with Composite Cement Fibre Materials

The combustibility of natural wood presents a negative impact for using this material in buildings. Timber elements can be cladded with boards made of non-combustible materials. This study represents a group of options for increasing the resistance of timber against the effects of fire and the possibility of slowing down the effect of thermal degradation of wood. The aim of this study is focused on an experimental testing of structures with timber elements protected by cement fibre boards as a non-combustible fire retardant. Cement fibre boards are fibre-reinforced composite materials used for systems of dry constructions. These boards present the highest degree of fire reaction class (A1). The behaviour of the structure, loaded by the effects of fire, was monitored during the experiment. The specimen was tested with reduced dimensions. The temperature loading corresponded to the procedure according to the standards. The final fire resistant (FR) results were evaluated in accordance with the requirements for the selected limit states of FR. This was assessed based on the measured temperatures and the whole condition of the tested specimen. The specimen fulfilled the fire-separating function of the structure for the classification times.

Fire reaction and post-fire impact properties of flax fibre reinforced composites containing intumescent flame retardants

The current research aims at investigating the fire reaction and post-fire impact characteristics of flax fibre reinforced composites based on different polymer matrices, such as epoxy resin and polypropylene (PP). The effects of stacking sequences of polymer sheets and flax fabrics within the composites are explored by a cone calorimeter. Heat release and smoke production results indicate that a top surface and number of flame-retardant polymer layers played significant roles in determining the fire reaction properties. Furthermore, post-fire impact properties of flax-epoxy and flax-PP composites depending on burning periods are analysed in this study at the first time. A fully instrumented drop-weight impact testing demonstrates that an increase in heat exposure time led a gradual decrease in impact properties of the composites due to fire-induced damages on fibres and polymers. However, pre-melting and re-consolidation of PP are beneficial to have higher impact energy and force of the flax-PP composite over those of the flax-epoxy counterpart. In addition, the char formation of composites due to intumescent flame retardant enhances the fire reaction properties of composites, whereas there is no significant influence on the post-fire impact characteristics due to highly brittle nature of carbonaceous char.