Investigation on the Fire Resistance and Reaction Properties of Woven Jute Fibre Reinforced Epoxy Composites

Thermal degradation, fire performance and combustibility of ceramified composites incorporating waste glass for sustainable building applications

The maritime transport is guilty for about 2.5% of global greenhouse gases emission, since 940 million tonnes of CO2 are emitted around every year. Moreover, even though now the 96% of ships can be recycled, current recycling practices cause negative environmental impacts. Indeed, researches carried out on ‘ships graveyard’ showed a concentration of petroleum hydrocarbons 16,793% higher than at the control. Epoxy Fibres Reinforced Composites (FRCs) are sustainable candidates in this field. In fact, having the FRCs structures a light weight, fuel-efficient ships can be built. The global epoxy composites market size was valued at USD 25.32 billion in 2019 and is expected to expand at a compound annual growth rate (CAGR) of 6.2% from 2020 to 2027. In this sense, in the next few years, the market is expected to rapidly replace conventional materials with epoxy composites in several fields, including the marine one. However, concerns about their non-recyclability are rising more and more. In this study, by following a twofold “design for recycling” and “design from recycling” approach the chemical recycling process for thermoset polymer composites developed by Connora Technologies (California, USA) was considered as solution to overcome this issue. Moreover, the adoption of natural fibres, i.e. flax, and bio-based epoxy resin was used as environmentally-friendly solution to even avoid the use of petroleum based raw materials. To follow the first approach, i.e. “design for recycling”, Flax FRCs with bio-epoxy matrices were first produced via hand lay-up with vacuum bagging. Next, they were chemically treated to obtain a recycled thermoplastic (rTP). Then moving on the “design from recycling” approach, a reuse strategy was developed by exploiting the Electrospinning technique and producing electrospun fibers suitable for the interlaminar toughening of composite laminates.

Self-extinction of timber

Mechanisms of flame spread and burnout in large enclosure fires

SUMMARYThis study investigates the fire reaction properties of concrete made with recycled rubber aggregate (CRRA). Four different concrete compositions were prepared: a reference concrete (RC) made with natural coarse aggregate and three concrete mixes with replacement rates of 5, 10 and 15% of natural fine and coarse aggregate by recycled rubber aggregate (RRA) obtained from used tyres. Specimens of CRRA were tested in a cone calorimeter according to the test standard ASTM E1354, submitted to heat fluxes of 25, 50 and 75kW/m2. These tests evaluated the effects of incorporating RRA in the fire reaction properties of concrete, namely in the heat release rate, the time to ignition (TTI), the remaining mass, the production of smoke, and the release of carbon dioxide and carbon monoxide. Owing to the organic nature of RRA, with the exception of the carbon monoxide yield, higher replacement rates of natural aggregates by RRA and increasing heat flux led to a worse fire reaction response, particularly in terms of TTI, heat release rate and smoke production. Results of these experiments were then used to estimate the European fire reaction classes of each concrete composition, using a flame spread model. All CRRA compositions tested were provisionally rated as class A2 or B and such ratings allowed defining the field of application of each solution under analysis, according to building code requirements. Copyright © 2011 John Wiley & Sons, Ltd.

Numerical analysis of piloted ignition of polymeric materials

In this work, the downward flame spread of flame of flexible polyurethane (FPU) foam with a different width was studied in an external radiant heat source. The effects of external radiation heat flux on the main parameters of flame spread, such as the flame height, mass loss rate, flame spread rate and flame pulsation frequency were investigated. The experimental results show that the flame spread of the FPU is an accelerating process when there is an external radiation condition and is a steady one without it. As the flame spread over board, the amount of pyrolysis gases involved in the combustion process showed a positive relationship with the external radiation heat flux. The flame height is under a combined effect of width and external radiation heat flux. However, the flame pulsation frequency shows a negative correlation with the fuel width and the radiation heat flux. Finally, an empirical equation approximation of linear pool fire is introduced to analyze the flame spread behavior of FPU as well as the validation with experiment data.

In this study, the heat-blocking performance of intumescent coating under various combinations of external radiative and convective heat fluxes is investigated numerically. The results show that the temperature distribution and heat fluxes near the coating surface are significantly affected by the heat-source combination, and consequently, the thermal responses of coating are different. For the same magnitude of convective heat source, the higher flame temperature (lower heat convection coefficient) has larger thermal effect on coating response. For the same magnitude of heat source, the radiative heat source generates more thermal response of coating than the convective one. Moreover, if the external heat flux is not intense enough to cause large expansion ratio (2 < xL/L < 11) in 3600 s, the combination of heat source can significantly affect the substrate temperature and the total heat flux at the coating surface. However, if the expansion ratio is sufficiently large (xL/L > 11) at the quasi-steady-state (3600 s), the substrate temperature and the total heat flux are independent of the combination of heat source, which only affects the temperature and the radiative and convective heat fluxes near the coating surface (∼3 mm in this study).

The present study focuses on ignition and combustion characteristics of phenolic fiber-reinforced plastic (FRP) with different thicknesses under different external heat fluxes using cone calorimeter, which receives little attention to date. A series of parameters including ignition time, thermal thickness, mass loss factor, mass loss rate (MLR), heat release rate (HRR), total heat release (THR), fire performance index (FPI) and fire growth index (FGI) are measured or calculated. Results indicate that the ignition time increases with the thickness, but decreases with the external heat flux. Phenolic FRP with thickness of 3 mm may be considered as thermally thin material. However, phenolic FRP with thickness of 5 and 8 mm is prone to be thermally thick material. The critical heat flux, minimum heat flux and ignition temperature are deduced and validated. The thermal thickness increases with the external heat flux. Linear correlations of the thermal thickness with the ratio of specimen density and external heat flux are demonstrated and presented. The mass loss factor decreases with the thickness. Three and two peak MLRs occur in the cases of low and high external heat fluxes, respectively. The average MLR increases with the external heat flux and thickness. The average and maximum HRR increases with the external heat flux. The FGI for the maximum HRR increases with the external heat flux. Linear correlations of the average MLR, the average and maximum HRR and the FGI for the maximum HRR with the external heat flux are demonstrated and presented.

Ablation is an effective and reliable method largely used in aerospace structures and other high temperature conditions to protect the payload from the damaging effects of external high heat flux. In an ablation process, the high heat fluxes are dissipated by the material through a series of endothermic processes. This finally leads to the loss and the consumption of the material itself. The ablative material keeps the surface temperature within a certain range, and as a consequence an increase of the heat flux will not cause a consistent temperature rise, but will bring about an increase of the surface recession rate. The objective of this work is to give information on the effect of the external heat flux to evaluate effective thermal diffusivity behavior and ablation performance of carbon fiber reinforced composite based on novolac resin. Here, we calculate the effective thermal diffusivity of this composite at different heat flux conditions using inverse solution technique of conservation equations of mass and energy. The ablation performance evaluation is based on experimental transient ablation rate measurement in oxyacetylene flame test. The results of this work explained the ablation process and thermal diffusivity behavior of this composite as a high performance heat shield at high external heat fluxes.

The boiling process is an efficient and effective heat transfer mode. Generally, different parameters such as temperature, pressure, external forces, etc., amend the pool boiling heat transfer (PBHT) rate. The present article uses molecular dynamics (MD) simulation to study the efficacy of different external forces(EFs) and heat fluxes (HFs) on the atomic and PBHT of water/Fe nanofluid (NF) flow. This study is performed in a microchannel (MC) with Fe-walls. The atomic behavior of the simulated structure is examined using the change in maximum temperature (T), maximum velocity(V), and maximum density(D), and the PBHT is studied by the phase change time (PCT) and HF. Results show that the maximum values of T, V, and D increase with increasing the EF and HF. Numerically, with increasing EF from 0.001 to 0.005 eV/Å, the maximum D, maximum V, and maximum T increase from 0.033 atom/Å 3 , 0.038 Å/fs, and 789 K to 0.034 atom/Å 3 , 0.039 Å/fs, and 900 K, respectively. Also, the result appears that the HF increases by increasing the applied EF, and the PCT reduces from 0.33 to 0.32 ns. So, the PBHT in the NF improves with increasing EF. On the other hand, the increase in external HF led to a reduction in the PCT (from 0.33 to 0.21 ns).

The addition of nanofiller into the fiber-reinforced composites aims to enhance adhesion between the fiber surface and the polymer matrix and improve strength. This paper examines the mechanical properties and morphological characteristics of fishtail palm empty fruit bunch (FTPEFB) fiber to evaluate its suitability as a reinforcing material in epoxy composites. The objective of this study was to evaluate the effects of Nanoclay reinforcement and surface treatment of FTPEFB fiber on the performance of fiber-reinforced composites. The FTPEFB fibers were prepared in three forms: untreated, alkali-treated, and benzoyl chloride-treated. Composites were prepared using these fibers with different Nanoclay levels: 0, 2, 4, and 6 wt. % through the hand layup method. Various mechanical characteristics were assessed, including tensile strength, flexural properties, impact resistance, and hardness of the surface. Furthermore, morphology was examined using Scanning electron microscopy to investigate how chemical processing affected the treated and untreated fibers. For alkali-treated FTPEFB fiber-reinforced epoxy composites, the best overall characteristics were achieved with 6 wt. % Nanoclay content, yielding a tensile strength of 77.52 MPa, a tensile modulus of 5.24 GPa, and a flexural strength of 142.8 MPa; the impact strength increased by 23.51%, and the hardness improved by 10.76% when compared to composites without Nanoclay fillers.

Laminated glass is prominently used nowadays as building construction material in the façade and architectural glazing of high-rise buildings. On the other hand, the fire safety of the high-rise building with laminated glass is also receiving more attention from the fire safety regulatory authorities and researchers due to recent fire incidents. Different interlayer polymeric materials are used in modern laminated glass to prevent the breakage of the glass façade, which can also increase the fire risk through a lower ignition time, and higher heat release and smoke production. Therefore, further research is required to understand the fire behaviour of laminated glass. In this study, the fire performance of the laminated glass has been investigated using cone calorimeter testing and the effect of different parameters such as glass thickness (6, 10, 12 mm), interlayer materials (PVB, SGP and EVA) and heat flux (25, 50 and 75 kW/m2) on the fire behaviour of laminated glass has been studied. It is found that the glass thickness, interlayer material and heat flux can significantly influence the reaction-to-fire properties such as peak heat release rate (pHRR), total heat release, time to ignition, and smoke production of laminated glass. In addition, total smoke production (TSP) is also very high for PVB (3.146 m2) and SGP (3.898 m2) laminated glass compared to EVA (0.401 m2) laminated glass and it is affected by these parameters. Finally, a simplified equation is developed to predict the pHRR of laminated glass by correlating the mass loss and external heat flux.

An expansion of a numerical model for the method of adiabatic cross-section developed previously to study the pulsed asymmetric heating of pipes by an external heat flux’ for the conditions of stationary heating is given to calculate therraophysical parameters of cooled pipes containing twisted tapes. Introduction of the generalized parabolic temperature distribution across the wali matched with conditions of heating and cooling of the pipe cross-section allowed to retain a two-dimensional diagram. Adeauate stationary distributions of thermophysical parameters have been obtained by a time-limited transition for the processes of heating and cooling. The proposed modification for the technique of adiabatic cross-sections is illustrated by the results of calculations for the expected distributions of thermophysical and strength parameters in pipe cross-sections containing heat-exchange intensifiers twisted tapes within the collector of deviated ions in the T-15 tokamak injection system under possibl...

Fiber-reinforced composites are widely used in various industries. Hybridization improves the mechanical strength and versatility of these materials. Specifically, combining plant fibers with synthetic fibers enhances performance of biocomposites and environmental sustainability. This study fabricated five fiber-reinforced epoxy biocomposites (KKKKK, GKKKG, GKFKG, GFKFG, and GKGKG) from kenaf (K), flax (F), and glass (G) fibers using hand lay-up and vacuum bagging techniques. The epoxy matrix was mixed with nano-silica. These biocomposites were evaluated for tensile and flexural properties, water absorption, physical behavior, and specific strength. The results showed that hybrid fiber composites had significantly higher mechanical properties than pure kenaf composites. The tensile and flexural strengths of GFKFG were 103.79% and 196.32% higher than KKKKK, respectively. Additionally, hybrid biocomposites had superior moisture absorption, with GKFKG absorbing 45.59% and 48.52% less moisture in distilled water and artificial seawater, respectively, compared to KKKKK. Hybrid biocomposites also exhibited higher specific strength and thinner thickness, making them suitable for lightweight and compact structures. In conclusion, hybridizing kenaf fibers with flax and glass fibers enhances performance of biocomposites, promoting their use in marine, aerospace, and automotive applications, contributing to sustainable development.