Fire Properties Research Articles

Halloysite infused jute fiber/poly (3-hydroxy-butyrate-co-3-valerate) bionanocomposites: Thermal, mechanical and fire retardant properties

Biocomposites have become more mainstream over the past decades for preserving the environment and producing sustainable materials as a potential substitute to synthetic polymer based composites derived from scarce petroleum materials. However, it is essential to investigate their mechanical, thermal and fire retardancy performance to answer the question of their suitability in automobile, biomedical, construction, film packaging, and commercial industries. In this work, we have studied one such promising biocomposites, jute fiber/poly (3-hydroxy-butyrate-co-3-valerate) (PHBV) and investigated their aforementioned properties. At first, 3–15 wt% halloysite nanotubes (HNTs) were dispersed in PHBV/chloroform mixture using an ultrasound process. PHBV/HNTs thin films were then prepared using the solvent casting method. Finally, jute fiber/PHBV-HNTs bionanocomposites were prepared using the compression mold method. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) tests were performed to study the thermal and fire retardancy properties. Uniaxial tensile and flexure tests were also performed to investigate the mechanical properties. In addition, scanning electron microscopy (SEM) was carried out to analyze the fracture surfaces of flexure tested samples. Results of jute/PHBV composites showed a significant increase in thermal and mechanical properties at 5 wt% HNTs loading in comparison to neat composites (without HNTs). In contrast, the composites with 15 wt% loading showed superior fire retardancy. SEM images of flexure tested samples showed enhanced interfacial bonding and less fiber pullout when compared to neat counterparts.

Preparation of a cobalt metal-organic framework (Co-MOF) and its application as a polypropylene flame retardant by compounding with melamine polyphosphate

A cobalt metal-organic framework (Co-MOF) was successfully prepared, and its combination with melamine polyphosphate (MPP) was studied to enhance the fire retardant properties of polypropylene (PP) composites. The morphology, composition, and structure of PP/MPP/Co-MOF composites were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The maximum limiting oxygen index of the PP/MPP/Co-MOF composite was 26.8%, which is 49% higher than that of pure PP and its combustion grade reached the V-0 level. When 2 wt% Co-MOF was added, the carbon residue of the composite reached 19.6 wt%, peak heat release rate was significantly reduced, smoke emission was suppressed, fire growth index was significantly reduced, and the fire risk of the composite was effectively reduced. Analysis of the carbon residue showed that aggregated carbon spheres were present on the carbon residue surface of the composite material supplemented with Co-MOF. The generation of carbon spheres effectively prevented the heat exchange and release of combustible gas during the combustion of the composite material, significantly improving the flame retardancy and stability of the material. As a new material, MOF has great innovation and necessity in researching polymer flame retardant. Moreover, the latest composite materials synthesized in this paper contribute to environmental safety to a great extent.

Fire safety performance of 3D GFRP nanocomposite as a cladding material

Vertical fire spread along highly flammable claddings is a major safety issue for buildings. In this project, a potential new type of cladding material, 3D Glass Fibre Reinforced Polymer (3D GFRP) with improved thermal stability, and fire performance is developed. 3D GFRP nanocomposite samples were fabricated with different percentages of Sepiolite (Sep), Sepiolite-phosphate (SepP), Ammonium Polyphosphate (APP) flame retardant, and 3D glass fabrics. Synthesis of SepP, dispersion analysis of nanoparticles, and manufacturing process have been studied. The characterisation of materials was conducted using Scanning Electron Microscopy, Helium Ion Microscopy, Transmission Electron Microscopy, Thermogravimetric Analysis (TGA), and X-ray Diffraction Analysis. The thermal stability and fire behaviour of the 3D GFRP nanocomposite was studied via TGA and cone calorimeter test. TGA results showed that the optimum amount of additives that improved the thermal stability is 15% flame retardants. Results of cone calorimeter tests showed that different percentages of APP, Sep, and SepP decreased the peak of the heat release rate between 4% and 42%. Also, the effects of APP flame retardant in improving thermal and fire reaction properties were more than Sep and SepP. The test results of 3D GFRP nanocomposite also showed a prospective cladding that can benefit the construction industry in near future.

Characterisation of eco-friendly self-compacting geopolymer concrete for fire endurance properties

Characterisation of eco-friendly self-compacting geopolymer concrete for fire endurance properties

Scale modelling experiments on the effect of longitudinal ventilation on fire spread and fire properties in tunnel

Fire spread between vehicles is of a great concern in a tunnel fire. Longitudinal ventilation, which is commonly used for the smoke control in tunnel fire, would inevitably affect fire properties and fire spread in tunnel at the same time. Such effects were studied using model-scale experiments in this paper. The results show that fire spread mostly occur due to the flame touching arising from flame tilting under longitudinal flow. Safety spacing should be kept for preventing fire spread between vehicles. The effect of longitudinal ventilation on the temperature distribution in the downstream area of the fire source is found mainly limited to the vicinity of the fire source. Maximum ceiling temperature, flame tilt angle and downwind flame temperature under longitudinal ventilation are found to be heavily dependent on Fr (Froude number) and dimensionless Q* (Dimensionless heat release rate). The formulas of flame tilt angle and mean downwind flame temperature were developed and predicted results were compared with those in modelling experiments.

Fire and termite resistance of wood treated with PF6-based ionic liquids

Six PF6-based ionic liquids (ILs) were investigated to evaluate their potential as chemicals for enhancing fire and termite resistance of wood. The ILs used in this study included 1-methyl-1-propylpyrrolidinium hexafluorophosphate ([MPPL]PF6), 1-methyl-1-propylpiperidinium hexafluorophosphate ([MPPR]PF6), 1-ethyl-3-methylimidazolium hexafluorophosphate ([EMIM]PF6), tetrabutylphosphonium hexafluorophosphate ([TBP]PF6), trihexyltetradecylphosphonium hexafluorophosphate ([THP]PF6), and 1-butylpyridinium hexafluorophosphate ([BPYR]PF6). All of the IL-treated wood samples did not undergo any morphological changes, and exhibited enhanced fire- and termite resistance compared with untreated wood. The fire resistance properties of all of the prepared IL-treated wood specimens were comparable. However, the [EMIM]PF6- and [THP]PF6-treated wood showed slightly inferior termite resistance among the tested IL-treated woods. Overall, [TBP]PF6 was the most promising candidate among the evaluated PF6-based ILs because it is stable in wood without leaching after water penetration.

Effect of pressure and stacking method on combustion characteristics of paper stacks

The experimental study on the combustion characteristics of paper stack fires was carried out in a low-pressure chamber. The variability of which with different environmental pressures and stacking methods were investigated. The mass of each group of experimental paper strips was 107 g. Three iron frames had the same volume, but different lengths and widths, and the strips were placed evenly in the frames to simulate different ways of paper stacking. The combustion tests of the paper stack were conducted at four ambient pressures of 101 kPa, 80 kPa, 60 kPa, and 40 kPa, respectively. The parameters measured during the experiments included mass loss, heat release rate (HRR), and flame temperature. The experimental results showed that the stacking type and pressure significantly affected the properties of the paper stack fire. For instance, the burning rate was influenced by the cross-sectional combustion area, pressure, and load height. There was a linear relationship between the ratio of the peak burning rate to the characteristic length of the bottom surface and the pressure-load height. The intensity factor of the paper stack fire was closely related to the environmental pressure: the paper stack fire under atmospheric pressure was generally a fast-growing one, which was a medium-growing fire under about 80 kPa. In comparison, that was a slow-growing fire when the pressure was 60 kPa.

Fire Properties of Hybrid Composites

Thermal conductivity of a components subjected to high temperature is an important property to be considered in a materials to be used in automobile and aerospace fire designated zones; likewise, it is availability, cost, stiffness, resistant to corrosion, and its strength. The main aim of the study is to investigate the fire behavioural properties of fibre metal laminates (FML) composite of a metal, synthetic, natural and polymer matrix. The composites were fabricated in a mould using hand lay-up method and allow to cured before test.. The fire property test was carried out using the standard properties test equipment as ISO 2685 propane burner thermocouples and heat flux meter. The result of the properties test shows a remarkable increase in the properties of only natural fibre metal laminate composites, with a slight decrease in the properties of pure synthetic fibre metal laminates. Flax composite has a high percentage of 21.43% of thermal conductivity and withstand the flame temperature for 15 minutes using an ISO 2685 standard while kenaf composite fail at 10 minutes 30 seconds, Conclusively, the composites can be used as the component in fire designated zones of automotive, aerospace and other machines.

Highly thermo-stable resveratrol-based flame retardant for enhancing mechanical and fire safety properties of epoxy resins

The integration of flame-retardant additive with both excellent thermal stability and remarkable fire-retarded efficiency into epoxy resins (EP) is highly demanded while challenging. Herein, a novel bio-based flame retardant (referred to DPOR) was synthesized via one-step reaction of resveratrol and diphenylphosphonyl chloride. The as-prepared DPOR exhibited outstanding thermal stability, with an initial thermal decomposition temperature of 438.4 °C, contributing from the reduced intermolecular π–π interaction and incremental oligomerization during the heating process. It was further utilized as additive for the manufacture of high-performance EP composites (EP-DPOR). Notably, DPOR can also act as mechanical reinforcer that enhanced the strength and toughness of EP. The EP-DPOR3 (3 wt% DPOR) showed a superior stretchability (15.9 %) and high tensile strength (59.3 MPa) compared to neat EP (12.4 %, 46.7 MPa). Additionally, the burning test results indicated that DPOR endowed the EP with greatly enhanced flame resistance, achieving a UL-94 V-0 rating with an increase of LOI values to 34.5 % at a low loading of 5 wt%. In cone calorimeter tests, it showed that heat and smoke release was effectively inhibited during combustion in comparison with EP, wherein the PHRR value of EP-DPOR was 27.5 % lower than EP. Thus, it is highly anticipated that DPOR, as a new type of bio-based flame retardant with superior thermal stability and efficient flame- retardant properties, holds a great potential for the development of next-generation flame retardant.

Evaluation of smoke gas toxicity and smoke density of bus interior materials

AbstractMaterials used for interior parts in buses are today fire classified according to UNECE Regulation 118, evaluating the horizontal and vertical burning rates and the melting behaviour. However, in recent accidents, the smoke has been identified as the critical parameter for deaths. An evaluation has been made of six materials used as interior parts in busses and is presented in this paper. Fire testing was conducted according to UNECE R 118 and smoke production including smoke gas toxicity was further evaluated with the smoke chamber test, EN ISO 5659‐2 and EN 17084. All six tested materials fulfilled the requirements of UNECE R 118; however, most materials showed fire properties which are not desirable, such as dark smoke and melting of large burning pieces. The tests with the smoke chamber showed that all materials gave a very high smoke production, in fact a smoke density value of the highest possible for the equipment to measure. This occurred only after a few minutes of test time. Thus, it can be concluded that this high smoke production will, in case of fire in a bus, reduce the visibility, and limit the ability of the passengers to safely evacuate. In addition, several toxic gases were detected in the smoke, both irritants and suffocating gases.

A critical assessment of the fire properties of different wood species and bark from small- and bench-scale fire experiments

A critical assessment of the fire properties of different wood species and bark from small- and bench-scale fire experiments

Water sorption, thermal, and fire resistance properties of natural shell‐based epoxy composites

AbstractIn this study, walnut shell (WSh), hazelnut shell (HSh), and mussel shell (MSh) waste as inexpensive reinforcements were recycled for the preparation of epoxy composite materials. Subsequent used inexpensive fillers are chars (WShC and HShC), which are the pyrolysis solid products of the natural WSh and HSh wastes. Three types of epoxy resins: bisphenol‐A type (DGEBA), modified with polyurethane (MER with PU), and rubber modified (MER with rubber) epoxy resins were used as the matrix in MSh composites. Thermogravimetric analysis of the composites showed that the thermal strength of the epoxy matrix increased significantly with the MSh and chars. The best water sorption results were obtained with the MSh. The contact angle values of MSh composites prepared with DGEBA epoxy resin were quite high (111°–113.5°) and their water retention values ranged from 0.2% to 0.32%. The composites that were produced using 50 wt% chars and the same epoxy resin showed better flammability stability. The full extinction times were determined as 63 and 58 s for WShC and HShC composites, respectively.

Fire Propagation Characteristics and Fire Risks of Polyurethanes: Effects of Material Type (Foam & Board) and Added Flame Retardant

Polyurethane material is used as an interior finish and wall cavity insulation. Flame-retardant products may be used for ignition, flame diffusion, and heat-release blocking. A large-scale test was conducted to understand the flame propagation characteristics of polyurethane with the addition of a flame retardant. The fire propagation properties and fire risks of four commonly used polyurethane materials were examined using three tests. Specifically, ignition properties, flame propagation behavior, and flashover occurrence were probed using full-scale tests, while heat release and fire characteristics were examined using cone calorimeter tests, and the toxicity of gaseous combustion products was assessed using gas toxicity tests. PIR F and PIR B, which contained flame retardants, featured slow flame propagation and a long-lasting residual flame, and PIR F released HCl and Br2 on combustion. Full-scale tests revealed that although external flame propagation was always accompanied by flashover, irrespective of whether the flame retardant was present, a delay or blockage of energy transfer to the inside was observed for flame-retardant-containing specimens. Apart from checking the safety at the material level, the importance of identifying the actual fire characteristics through a full-scale test was confirmed.

The fabrication of phytate and LDH-based hybrid nanosheet towards improved fire safety properties and superior smoke suppression of intumescent flame retardant LDPE

An effective fire retardant system was developed composed by traditional intumescent flame retardant (IFR) and a new-typed nano-synergist (PAMA-SDBS-LDH, P@L), and their synergistic effect and mechanism on the thermal stability and flammability properties of low-density polyethylene (LDPE) was comprehensively studied. Briefly, the nano-synergist was successfully prepared by using melamine, phytic acid and Zn-Ni-Al layered double hydroxide (LDH) according to hydrothermal method. By adding 0.5% PAMA-SDBS-LDH and 29.5% IFR, the fire retardant properties of LDPE composite (LDPE/I/P@L) reached V-0 rating in UL-94 test. The total smoke production of LDPE/I/P@L decreased by 69.8% compared with LDPE. It is confirmed that PAMA-SDBS-LDH nanosheet is an efficient synergist to promote the formation of high-quality char layer via multiple fire retarding mechanisms. The good mechanical properties of LDPE/IFR system are also maintained by incorporating PAMA-SDBS-LDH. Undoubtedly, this study will provide valuable insights into improving the fire retardant efficiency and practical application of traditional IFR.

FIRE AND EXPLOSION CHARACTERISTICS OF ENERGY WILLOW BIOMASS DURING THE SUPERHEATED STEAM DRYING PROCESS

In this paper the explosive and fire properties of energy willow dust were experimentally determined before and after drying with superheated steam at temperatures of 120°C, 140°C, 160°C and 180°C. The conducted research has shown that the parameters of the operation of the installation of drying with superheated steam of the energy willow biomass have a decisive impact on the fire-explosive characteristics of the dust produced. The results indicate that the higher the drying temperature, the stronger the probability of ignition of the willow dust cloud, the faster the flame propagation and the higher the explosion intensity. Although the superheated steam drying installation for energy willow biomass is considered to be safe, the probability of occurrence of a fire or explosion events of the biomass dust-air mixture is likely.

Thermomechanical and Fire Properties of Polyethylene-Composite-Filled Ammonium Polyphosphate and Inorganic Fillers: An Evaluation of Their Modification Efficiency.

The development of new polymer compositions characterized by a reduced environmental impact while lowering the price for applications in large-scale production requires the search for solutions based on the reduction in the polymer content in composites’ structure, as well as the use of fillers from sustainable sources. The study aimed to comprehensively evaluate introducing low-cost inorganic fillers, such as copper slag (CS), basalt powder (BP), and expanded vermiculite (VM), into the flame-retarded ammonium polyphosphate polyethylene composition (PE/APP). The addition of fillers (5–20 wt%) increased the stiffness and hardness of PE/APP, both at room and at elevated temperatures, which may increase the applicability range of the flame retardant polyethylene. The deterioration of composites’ tensile strength and impact strength induced by the presence of inorganic fillers compared to the unmodified polymer is described in detail. The addition of BP, CS, and VM with the simultaneous participation of APP with a total share of 40 wt% caused only a 3.1, 4.6, and 3 MPa decrease in the tensile strength compared to the reference value of 23 MPa found for PE. In turn, the cone calorimeter measurements allowed for the observation of a synergistic effect between APP and VM, reducing the peak heat rate release (pHRR) by 60% compared to unmodified PE. Incorporating fillers with a similar thermal stability but differing particle size distribution and shape led to additional information on their effectiveness in changing the properties of polyethylene. Critical examinations of changes in the mechanical and thermomechanical properties related to the structure analysis enabled the definition of the potential application perspectives analyzed in terms of burning behavior in a cone calorimetry test. Adding inorganic fillers derived from waste significantly reduces the flammability of composites with a matrix of thermoplastic polymers while increasing their sustainability and lowering their price without considerably reducing their mechanical properties, which allows for assigning developed materials as a replacement for flame-retarded polyethylene in large-scale non-loaded parts.

Fire resistance properties of heavyweight magnetite concrete in comparison with normal basalt- and quartz-based concrete

Nowadays application of radiation shielding structures grows over the world. Nuclear buildings represent one of the most complicated radiation shielding structures; that is why a particular type of concrete is required to withstand different conditions during their lifespan. Unique properties such as the behaviour under elevated temperatures, radiation shielding, and thermal stability properties are essential to guarantee the fire resistance safety of nuclear buildings. However, some gaps are still there, warranting further investigation, particularly the thermal stability and fire-resistance properties of the heavyweight concrete. The properties are mechanical, physical, and deformation properties of concrete after being subjected to elevated temperature. This paper investigated the fire resistance properties of three concrete mixes. There were magnetite-based concrete, basalt-based concrete, and quartz-based concrete. Compressive and flexural strength, spalling, mass loss, porosity, and scanning electron microscopy were measured for the three concrete types after being subjected to different temperature steps at 20, 150, 300, 500, and 800 °C. The three types of concrete showed different fire resistance properties. Magnetite-based concrete has better heat/fire resistance than basalt- and quartz-based concrete; there was no significant change up to 500 °C, and explosive spalling occurred at 800 °C. Correspondingly, the maximum change in porosity and reduction in the compressive and flexural strength occurred at 300 °C, which indicates the good thermal stability of magnetite-based concrete. Concerning basalt-based and quartz-based concretes, cracks were observed at 500 °C, and cracks with colour change and small spalling were initiated at 800 °C. Therefore, the maximum growth in the porosity and the high reduction in the compressive and flexural strength in basalt-based concrete occurred at 800 °C. Likewise, the extreme change in the porosity occurred at 500 °C, and the drastic reduction in the compressive and the flexural strength in the quartz-based concrete was relatively high at 500 °C and 800 °C. The SEM observations and analysis obtained the appearance of microcracks, voids and degradation of C-S-H in different concrete mixes at 500 and 800℃.

Experimental demonstration of highly reliable dynamic memristor for artificial neuron and neuromorphic computing

Neuromorphic computing, a computing paradigm inspired by the human brain, enables energy-efficient and fast artificial neural networks. To process information, neuromorphic computing directly mimics the operation of biological neurons in a human brain. To effectively imitate biological neurons with electrical devices, memristor-based artificial neurons attract attention because of their simple structure, energy efficiency, and excellent scalability. However, memristor’s non-reliability issues have been one of the main obstacles for the development of memristor-based artificial neurons and neuromorphic computings. Here, we show a memristor 1R cross-bar array without transistor devices for individual memristor access with low variation, 100% yield, large dynamic range, and fast speed for artificial neuron and neuromorphic computing. Based on the developed memristor, we experimentally demonstrate a memristor-based neuron with leaky-integrate and fire property with excellent reliability. Furthermore, we develop a neuro-memristive computing system based on the short-term memory effect of the developed memristor for efficient processing of sequential data. Our neuro-memristive computing system successfully trains and generates bio-medical sequential data (antimicrobial peptides) while using a small number of training parameters. Our results open up the possibility of memristor-based artificial neurons and neuromorphic computing systems, which are essential for energy-efficient edge computing devices.

Polydopamine primed phosphorylated sepiolite-polypropylene nanocomposite with enhanced thermal, rheological, and flame retardant properties

Phosphorous-based fire-retardant materials are considered eco-friendly and can be reinforced in polymers or functionalized on the polymer backbone to reduce combustibility. Herein, sepiolite fiber (Spl) was first primed with polydopamine (PDA), and the amine group density was increased by Michael's addition of EDA to further graft H3PO3. The stepwise modifications and formation of the phosphorylated Spl-PDA-P and Spl-PDA-EDA-P were established by analyzing surface chemical structure, surface and internal morphology, and surface area. Further, the Spl-based fillers were reinforced in the PP matrix, and the nanocomposites were systematically characterized for thermal stability, mechanical property, flow behavior, and fire-retardant properties. The PP_Spl-PDA-EDA-P nanocomposite at 5% filler loading has a tensile and flexural strength of 36.3 MPa and 50.6 MPa, respectively. The flow property was established by determining melt flow index (MFI) of 13.3 ± 0.75 g/10 min and melt rheological properties. After phosphorylation, the Spl-based fillers have shown shear thinning behavior with increased filler loading. Finally, the prepared nanocomposites were evaluated for fire retardant properties by determining the limiting oxygen index (LOI) and UL-94 vertical burning test. The neat PP has an LOI of 17.5, and a maximum improvement was observed in the case of PP_Spl-PDA-EDA-P with an LOI of 30.2. Overall, the grafting of H3PO3 on PDA coated Spl has created a robust filler to impart fire-retardant property in combustible PP.

Rendering passive radiative cooling capability to cotton textile by an alginate/CaCO3 coating via synergistic light manipulation and high water permeation

Personal thermal management textiles that put focus on cooling human body in hot environment attracts intense research interests since the urgent requirement for adjusting human activity to save energy even when we face extreme weather more frequently. Textiles produced from petrol-based fibers have shown their effective passive cooling effects. However, regeneratable passive cooling textiles are still lacking. In this study, we report a cotton-based effective passive cooling textile by interfacial engineering by alginate modification and in-situ generated CaCO3 particles. The Alg/CaCO3-cotton fabrics not only effectively cool the underlining surface via high reflectivity over solar spectra (∼90%) and high mid-infrared emissivity (0.97) in the atmospheric window, but also present enhanced water evaporation and water vapor permeation capabilities (36.51% higher water vapor transmission rate than pristine cotton fabric). The textile avoids overheating by 5.4 °C under direct solar irradiation, comparable to the performance of the reported petrol-based textile. The Alg/CaCO3-cotton also presents high washing stability, UV protection properties, faster drying and fire resistance properties. The surface engineering process is compatible with large-scale production. This work provides enlightening insights to regeneratable and wearable passive cooling materials and sheds light on the working mechanism of personal thermal management materials.