Horizontal Burning Research Articles

Improvement of the flame retardancy of polyamide 6 by the incorporation of UiO-66 and UiO-66/melamine

The flame retardancy of polyamide 6 (PA6) has been investigated through the incorporation of the metal–organic framework (MOF) UiO-66 and a composite of UiO-66/melamine during the extrusion process. The prepared materials have been characterised by various techniques: XRD, XPS, FTIR, TGA, DSC, SEM, EDX and mechanical properties. Moreover, to examine the efficiency of the flame retardants, the composites have been tested using the UL-94 vertical and, horizontal burning test, as well as the limiting oxygen index (LOI). The UL-94 V-2 standard has been achieved with only a 4 wt% load of either UiO-66 or UiO-66/melamine, compared to pure polyamide, which is not classified. The best results have been achieved with the UiO-66/melamine sample at 7 wt%, which prevents the agglomeration of UiO-66 alone. The highest LOI value was also obtained with this sample, achieving a value of 35.5 %, compared to pure PA6 and with UiO-66, which reached values of 22.4 % and 23.2 %, respectively. A flame suppression mechanism of the UiO-66/melamine composite is proposed, based on the formation of zirconium oxide, gas adsorption by the MOF and release of NH3.

Eco‐friendly flame‐retardant based on sap from banana plant pseudostems

AbstractSociety's need for safe flame‐retardant technologies in passive fire protection is undeniable. To address this concern, this paper presents an experimental investigation of the fire‐retardant properties of slash pine wood treated with banana plant pseudostem sap, obtained from a cultivated banana plant variety widely grown in Brazil. The natural sap extract was characterized through X‐Ray Fluorescence spectrometry and Fourier Transform Infrared Spectroscopy techniques, revealing the presence of key components, including water, potassium chloride, sodium chloride, sodium silicate, calcium phosphate, sodium phosphate, lignin and tannins. The authors explored different treatment parameters, including various sap impregnation times, number of impregnations and use of natural versus various levels of concentrated sap. First, a horizontal burning test, similar test to UL 94 HB, was used to obtain an initial assessment of the suitability of sap as a flame retardant for slash pine wood. Subsequently, the Mass Loss Calorimeter equipment with thermopile attachment described in ISO 13927:2015 was used to measure various heat release rate parameters. The findings suggest that reducing the water content in sap and increasing the number of repeat treatments results in a more effective treatment for slash pine wood. More specifically, the results indicate that the most efficient treatment involves three impregnations with high‐concentration (1/10 volume reduction) sap. Future work to improve the efficacy of the concentrated sap impregnation process could explore the use of pressure treatment instead of soaking.

Preparation and Characterization of Paving Blocks from Polyethylene-Based Plastic Waste and Natural Fibre

The current methods of managing plastic waste especially in developing countries have become an issue of environmental and public health concern globally. This has led environmentalists and scientists to work on finding day-to-day activities that can help to reduce the plastic waste disposal problem. Recycling and reuse of plastic waste into construction materials is a valid way to reduce the effect of this improper disposal of plastic waste. This will help to reduce the negative impact of the high cost of cement in the construction industry. In this research, polyethylene waste (table water sachet) was used as a replacement for cement in the construction of paving blocks. The sample with a 1:4 mixing ratio was found to have the highest compressive strength among the different mix ratio examined. Paving blocks were then produced with this mixing ratio from plastic-aggregates and plastic-aggregate-fibre and compared with the standard cement-aggregate paving blocks for their compressive and tensile strengths, water absorption, thickness swelling, density, and thermal properties (thermogravimetric analysis (TGA) and horizontal burning rate). Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray (EDX) was also conducted on the paving blocks to determine the distribution of the particles of the blocks, the compatibility of the matrix, and their elemental composition. The results of the compressive strength test showed 18.1667 Nmm<sup>-2</sup> for plastic-aggregate block, though lower when compared with the cement-aggregate block with a compressive strength of 21.6667 Nmm<sup>-2</sup>. The plastic-aggregate block has the least water absorption value among the three samples. The 0.1350% and 1.8861% water absorption values obtained for the plastic-aggregate and plastic-aggregate-fibre bricks respectively showed an impressive water absorption which falls within the maximum of 5% water absorption for quality paving blocks. The plastic-aggregate and plastic-aggregate-fibre both also recorded lower density when compared with the cement-aggregate block, which gives them a logistic advantage over the cement-aggregate block in the case of transporting them from one location to another. The blocks were found to be stable at low temperatures. The SEM images of the plastic-aggregate and plastic-fibre-aggregate paving blocks clearly showed a consistent dispersion of the plastic waste particles within the aggregate matrix over that of the cement-aggregate paving block. Therefore, plastic-aggregate brick can be recommended for use as paving bricks for low-traffic roads, walkways, parks, and gardens, although there is need to carry out further studies on other material properties of the plastic-based paving block.

Characterization studies of Sepia officinalis Bone Powder’s synergistic effect with aluminum hydroxide in the improvement of flame retardancy in flexible polyurethane foam

Flexible polyurethane foam (PUFF) is a versatile product. Though the PUFF has excellent properties, they lack flame retardance. To make the material more useful, the incorporation of flame retardant (FR) is inevitable. To impart these specific characteristics, Sepia officinalis bone powder (SOBP) and aluminium hydroxide (Al(OH)3) combined together are used as a filler (SBPA) along with PUFF in this current investigation. SOBP is used by varying different percentages (1 % to 5 %) (1 %-SBP1, 2 %-SBP2, 3 %-SBP3, 4 %-SBP4, and 5 %-SBP5). Based on the UL 94 Horizontal Burning (HB) rating test, the best rating was observed with 3 %-SBP3. Al(OH)3 was loaded by varying from 1 % to 5 % (1 %-SBP3A1, 2 %-SBP3A2, 3 %-SBP3A3, 4 %-SBP3A4, and 5 %-SBP3A5). UL 94 HB results with a burning rate of 1.3 mm/s for the SBP3A4 which is lesser than neat PUFF (PUFNF). Tensile strength (TS) was observed higher for SBP3A3 sample with 0.257 MPa (172 % elongation at break). Density and RR values were observed in the range of 34–46.5 Kg/m3 and 30–34, respectively. XRD analysis reveals SOBP fillers with a particle size of 0.24 µm and the crystallinity index values depict the amorphous nature. The second stage degradation temperature was found to be increased to 363 °C from 303 °C for both SBP3 and SBP3A4 filler addition in TGA analysis. SEM analysis decoded the open cell (OC) structure further confirms the formation of PUFF. The present study confirms the improvement of UL 94 HB rating and other properties in the prepared PUFF.

Flame retardancy and mechanical properties of polypropylene composites containing intumescent flame retardants, preceramic polymers, and other additives

AbstractThis study aims to investigate the flame retardancy and mechanical properties of polypropylene (PP)‐based intumescent flame retardants (IFRs) consisting of melamine phosphate (MP) and pentaerythritol (PER), and different additives; boron phosphate (BP), antimony oxide (AO), and preceramic polymers, namely poly(dimethylsilane) (PDMS) and poly(methylsilsesquioxane) (PMSQ). The composites were produced by twin‐screw extrusion, and then molded by injection molding. Their characterizations were performed with limiting oxygen index (LOI), horizontal burning tests, thermogravimetric analysis (TGA), tensile and impact tests. The total amount of IFRs and the additives in polypropylene was kept constant at 20 wt%. The additive concentration was varied as 1, 3, and 5 wt% in the composites. The highest LOI value of 29% was obtained for PP/MP/PER composite with MP/PER ratio of 3/1. PP/IFR‐based composites with 1 wt% additive exhibited higher LOI and horizontal burning performance than the other composites with 3 and 5 wt% additives. It is revealed that tensile modulus and impact strength of neat PP were improved with the addition of IFRs, and for each type and amount of the additives used in the study.Highlights Usage of IFRs, preceramic polymers, BP and AO in PP improved flame retardancy. Lower amount of additives (1%) in PP/IFR composites led to higher LOI values. Additive incorporation enhanced tensile modulus and impact strength of neat PP.

Production and Characterization of Fire-Retardant Coating Materials Using Gum Arabic for Cellulose Surfaces

Background and Objective: Fire retardants are substances that are applied to the surface of any combustible base which can delay the spread of fire or keep the structure intact against fire, thereby allowing sufficient time for safety measures to be taken. In this study, the production and chemical characterization of fire-retardant paint was achieved. Materials and Methods: The components used in the production of the paint include: Ammonium dihydrogen phosphate, Melamine, Urea, Gum Arabic, and paint base. The coating was prepared by blending all the components. Agilent Technology Cary 630 Fourier Transform Infra-Red (FTIR) analyzer was used to determine the structural characterization of the fire-retardant paint. A Horizontal burning test following the ASTMD635-75 standard procedure was employed to evaluate the flammability properties of the coated samples. The pH of the paint was determined with the aid of a pH meter. Density and percentage weight gain of the coated materials were also carried out. Results: The results obtained showed the density of the paint to have values ranging from 1.046 g/cm3 to 1.066 g/cm3 while the pH values range from 5.05 to 4.90. The FTIR spectra confirmed the presence of -NH2 amide group, C=O carbonyl group, C=C conjugated structure, C-O Stretching of inorganic carbonate, CH Aliphatic group, and C-O of carbohydrate. The Flammability measurement showed the burning rate to range from 2.227 mm/s to 1.25 mm/s. The ignition times were found to range from 3 to 4 s. The flame spread test values range from 6 to 8 s. Conclusion: From the results of the burning analyses, level 4 had the highest flame-retardant properties. There is a clear difference in the ignition time and burning rate of the coated samples compared to the uncoated reference.

Bismuth trioxide replaced diantimony trioxide to obtain polyvinyl chloride leather with high flame retardancy and low flame propagation rate

Diantimony trioxide (Sb2O3) has been widely used in polyvinyl chloride leather (PVCL, PVC powder: plasticizer = 50 phr: 50 phr). However, the EU and the IARC have included it in the list of restricted substances. In response to these restrictions on Sb2O3, this work developed a high flame retardant PVCL with reduced or no Sb2O3 content by introducing bismuth trioxide (Bi2O3). The results showed that the horizontal burning rate of 1Bi2O3/3Sb2O3/PVCL decreased by 51.2% compared to that of 4Sb2O3/PVCL. When the addition amount of Bi2O3 reached 6 phr, the horizontal burning rate of 6Bi2O3/PVCL decreased by 20.5% compared to that of 4Sb2O3/PVCL, which can achieve complete replacement of Sb2O3. The improved flame retardancy can be primarily attributed to the flame retardant effect of Bi2O3 in PVCL foam layer. During combustion, Bi2O3 facilitated crosslinking and charring in the PVCL foam layer matrix, contributing to condensed phase flame retardancy. Additionally, it promoted the decomposition of the PVCL foam layer matrix, generating more HCl (g), thereby enhancing gas phase flame retardancy. This study has developed a high flame retardant PVCL through a simple method, which was expected to meet the application needs of the automotive interior materials.

Enhanced flame retardancy and thermal stability in flexible polyurethane foam through synergistic core-shell structured DBDPE@PMA particles

This research presents the synthesis of core–shell structured flame retardant particles, DBDPE@PMA, which combines the flame-retardant and toughening functions. These particles utilize decabromodiphenyl ethane (DBDPE) as the core and a copolymer of methyl methacrylate and acrylic acid (MMA-AA) as the shell, which are created via emulsion polymerization. The process involved an initial reaction of DBDPE@PMA with isocyanate, followed by foaming with polyether polyol to fabricate flame retardant, and the flexible polyurethane foam (P/D-FPUF) was thermally insulated. The study examined the influence of DBDPE@PMA on the flame retardancy properties of flexible polyurethane foam. Scanning electron microscopy confirmed the encapsulation of DBDPE by the polymer, resulting in a core–shell composite particle. The interaction between the carboxylic groups (–COOH) on the DBDPE@PMA shell and isocyanate enhanced the interfacial bonding, thereby increasing the foam's apparent density and ensuring better integration with the polyurethane matrix. However, DBDPE@PMA had aggregates on the foam matrix bubble holes, resulting in uneven bubble holes. DBDPE@PMA markedly improved the flame retardancy and thermal stability of the foam, compared to both pure polyurethane and foam containing solely DBDPE (10D-FPUF). The oxygen index value of the foam with 20% DBDPE@PMA (20P/D-FPUF) reached 33.6%, with UL-94 horizontal and Vertical burning level tests achieving the highest classifications. The char residue after thermal degradation increased significantly from 1.93% in pure foam to 5.06%. While the smoke density level rose, the duration to peak smoke density was prolonged to 78 s, offering an enhanced margin for evacuation during the initial stages of a fire.

Assessing the Efficacy of Magnesium Hydroxide and Aluminium Hydroxide in Enhancing Flame Retardancy of Natural Fiber

Natural fiber panels have gained attention as sustainable alternatives in various applications, including construction and interior design. Although these fibres are highly valued for their environmental sustainability and acoustic advantages, they are inherently flammable. These panels, when subjected to fire or high-temperature conditions, pose significant safety risks due to their flammability and potential for rapid combustion. This study evaluates the efficacy of various synthetic additives in enhancing the flame retardancy of natural fiber panels. The panels were made by mixing the natural fiber with polyester resin and additives. The experimental setup includes standard fire tests such as ASTM D635 Horizontal Burning and ASTM D3801 Vertical Burning Test. The results show that rice husk demonstrates a slower burning rate when combined with both magnesium hydroxide and aluminium hydroxide, indicating better flame retardancy. Coconut coir outperforms rice husk and sawdust for both magnesium hydroxide and aluminium hydroxide which are 655 s and 640 s respectively in terms of vertical burning. The study showed that magnesium hydroxide is a better flame retardant than aluminium hydroxide. This makes it a promising option for enhancing the fire resistance of natural fiber panels.

Improving Fire Resistance in E-Vehicles: A Study on MPP-Enhanced S-Glass/Phenolic Hybrid Composites

The automotive industry has benefited greatly from the advancements in fireproof, high-strength fiber-reinforced polymer matrix composites during the last several decades. S-Glass/Phenolic hybrid composites made by hydraulic compression molding are the subject of this investigation into the effects of Melamine Polyphosphate (MPP) on their thermal and fire performance. In addition to studying the morphology of the samples, researchers analyzed the thermal and fire performances of hybrid laminates made with neat laminates and varying compositions of MPP (ranging from 3% to 15% by weight). Tests included UL 94, limiting oxygen index (LOI), and the impacts of accelerated heat ageing on the behavior of the hybrid specimens. The results demonstrated that specimens filled with higher MPP performed better in a fire compared to neat samples. According to the results in UL 94 horizontal burning test and vertical burning test, specimens filled with 12 and 15 wt. % MPP demonstrated a reduced flame spreading rate and fulfilled the V-0 criteria. Simultaneously, the energy absorption capacity of hybrid configurations is severely limited by heat ageing, due to its temperature and duration dependent. The research proved that the suggested S-Glass / Phenolic / Melamine Polyphosphate hybrid composites were suitable for creating environmentally friendly electric vehicle battery housings and fire-resistant automotive parts.

Nano Boron Oxide and Zinc Oxide Doped Lignin Containing Cellulose Nanocrystals Improve the Thermal, Mechanical and Flammability Properties of High-Density Poly(ethylene).

The widely used high-density polyethylene (HDPE) polymer has inadequate mechanical and thermal properties for structural applications. To overcome this challenge, nano zinc oxide (ZnO) and nano boron oxide (B2O3) doped lignin-containing cellulose nanocrystals (L-CNC) were blended in the polymer matrix. The working hypothesis is that lignin will prevent CNC aggregation, and metal oxides will reduce the flammability of polymers by modifying their degradation pathways. This research prepared and incorporated safe, effective, and eco-friendly hybrid systems of nano ZnO/L-CNC and nano B2O3/L-CNC into the HDPE matrix to improve their physio-mechanical and fire-retardant properties. The composites were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, thermo-gravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, horizontal burning test, and microcalorimetry test. The results demonstrated a substantial increase in mechanical properties and a reduction in flammability. The scanning electron microscope (SEM) images showed some agglomeration and irregular distribution of the inorganic oxides.

Flammability and Soil Burial Performance of Sugar Palm (Arenga pinnata (wurmb) merr) Fiber Reinforced Epoxy Composites

This study investigates the effects of soil burial and flammability on sugar palm fibre (SPF) (Arenga pinnata (wurmb) merr)-reinforced epoxy composites. In order to determine the flammability and biodegradability properties, experiments are conducted in accordance with ASTM standards. The hand lay-up method was used to fabricate composite samples with two different weight ratios between epoxy and SPF, which were 70:30 and 50:50. Biodegradability and flammability properties were investigated using horizontal burning tests, limiting oxygen index (LOI), cone calorimetry, and soil burial. It was found that the Epoxy/SPF-50 was the composite that exhibited the fastest degradability at 0.81%/week. The result of the horizontal burning test showed that the addition of SPF reduced the burning rate but slightly increased it at 50 wt% because the ratio between epoxy and SPF exceeds the optimum fibre loading. The Epoxy/SPF-50 exhibited a better LOI value at 23.3 than pure epoxy (control), which was 19.8. From the cone calorimetry test, it was observed that the time to ignition (TTI) and total heat release (THR) values were decreased when the amount of SPF increased. Char production increases the flame-retardant protection of SPF-reinforced epoxy composites. To the best of the authors’ knowledge, no published study has been conducted on the flammability and biodegradability characteristics of SPF-reinforced epoxy composites.

Fiber and future: Unleashing the power of industrial hemp waste through epoxy composites

AbstractNatural fiber composites offer a sustainable alternative to synthetic polymer composites, addressing the environmental concerns associated with traditional materials. This study aims to investigate the effect of flame‐retardant additives (magnesium hydroxide Mg(OH)2 [A] and aluminum hydroxide Al(OH)3 [B]) on hemp fiber‐based epoxy composites with a different fire retardant (FR) loading, that is, 0%, 8%, 12%, and 24%. An evaluation of flame‐retardant effectiveness on composites was carried out using thermogravimetric analysis, limited oxygen index (LOI), UL‐94 horizontal burning, morphological analysis scanning electron microscopy (SEM), and char residue analysis. The results show that introducing the flame retardants in the hemp–epoxy composites improved the thermal stability and flame retardancy of hemp–epoxy composites When composites were incorporated with flame retardants, the Horizontal burning rate was decreased, and LOI was increased. The lowest Horizontal burning rate of prepared composites was recorded as 11.6 mm/min, and the highest LOI was 25.3%. SEM shows uniform distribution of FR particles in the prepared composite. It is concluded that adding flame‐retardant additives efficiently improves the flame retardancy properties of the prepared composites.Highlights The mechanical and flammability behavior of developed composites were investigated after adding magnesium hydroxide and aluminum hydroxide to composites. An enhancement in flame retardancy and a slight reduction in mechanical properties are observed in composites. The purpose of this study is to expand the area where flame‐retardant ramie fabrics may be applied.

Effect of Rice Husk and Wood Flour on the Structural, Mechanical, and Fire-Retardant Characteristics of Recycled High-Density Polyethylene.

Given the rising consumption of plastic products, it is becoming imperative to prioritize the recycling of plastic items as a solution to reducing plastic waste and environmental pollution. In this context, this research focuses on assessing the impact of incorporating rice husk and wood flour into recycled high-density polyethylene (rec-HDPE) to analyze its mechanical properties, flammability, and thermal stability. The combined rec-HDPE content of wood flour and rice husk varied between 0% and 20%. The rec-HDPE content of maleic anhydride grafted polyethylene (MAPE) was fixed at 3%. Mechanical characteristics such as flexural, tensile, and impact strengths were assessed. Cone calorimetry (CC) tests, limited oxygen index (LOI) tests, and horizontal and vertical burning tests were performed to determine the flammability or fire retardancy of these composites. On the other hand, to characterize the thermal characteristics of these composites, thermogravimetric analysis (TGA) was used. To further characterize the fluctuation in these characteristics, scanning electron microscopy (SEM) and infrared spectroscopy (FTIR) studies were carried out. The mechanical characteristics were found to be increased in response to adding rice husk or wood flour. An 8% increase in tensile strength and a 20% increase in elastic modulus enhancement were recorded for a 20% rice husk-added composite. SEM revealed the reason for the variation in tensile properties, based on the extent of agglomeration and the extent of uniform distribution of fillers in rec-HDPE. Following these lines, the 20% rice husk-added composite also showed a maximum increase of around 6% in its flexural strength and a maximum increase of 50% in its flexural modulus. A decrease in impact strength was recorded for rice husk and wood flour-reinforced composites, compared with unreinforced rec-HDPE. Hybrid composites displayed a lack of mechanical strength due to changes in their nature. FTIR tests were performed for a much more elaborate analysis to confirm these results. Twenty percent of rice husk-added rec-HDPE displayed the best thermal properties that were tested, based on TGA and derivative thermogravimetric (DTG) analysis. This 20% composite also displayed the best fire-retardancy characteristics according to UL 94 tests, cone calorimetry tests, and limited oxygen index tests, due to the barrier created by the silica protective layer. These tests demonstrated that the incorporation of both fillers-rice husk and wood flour-effectively enhanced the thermal, mechanical, and fire-retardant attributes of recycled HDPE.

Aryloxyphosphazene-Modified and Graphite-Filled Epoxy Compositions with Reduced Flammability and Electrically Conductive Properties

A method has been developed for producing an epoxy composition based on a low-viscosity epoxy-resorcinol resin, a phosphazene-containing curing agent, isophoronediamine, and thermally expanded graphite as a filler. The degree of cure and the absence of side reactions during the curing process were confirmed using IR spectroscopy. The influence of the content of phosphazene-containing curing agent and filler on the physico-mechanical properties of the composition, its fire resistance, and antistatic properties were studied. Using the UL-94 HB horizontal burning test, it was found that the addition of 10 and 20 wt. % phosphazene-containing curing agent (relative to isophoronediamine) reduces the burning speed by 10 times compared to a sample without phosphazene. The addition of a filler to a composition containing phosphazene reduces the burning speed by 25 times compared to a composition without phosphazene and imparts antistatic properties to the epoxy composition, as evidenced by the specific volume electrical resistance of the order of 101 Ohm·m. Phosphazene-containing curing agent had no statistically significant effect on specific volume electrical resistivity (p > 0.05). Tests of physico-mechanical and adhesive properties (tensile strength, compressive strength, water absorption, water solubility, abrasion resistance, and adhesive strength) of filled epoxy compositions with 10 and 20 wt. % phosphazene-containing curing agent demonstrated that these properties met the requirements for floor coverings in construction and parts of electrical devices.

Intelligent polyester fabric with fire safety for personal temperature management

The stability of personal thermal management are increasingly indispensable in modern society due to the growing demand for energy savings and environmental protection. Herein, inspired by solid–liquid host–guest materials, we propose a coating preparation strategy that uses a solid flame-retardant gel as the host skeleton filled by a solid–liquid switchable phase change flame-retardant functional guest, thus fabricating smart polyester fabrics for personal temperature management in one step. Both attenuated total reflectance (ATR) and scanning electron microscopy (SEM) are used to confirm the host–guest structure coating on the surface of polyester fabric. Results from simulated cold and heating environments show that the coated polyester fabric has a desirable personal temperature regulation ability. The skin wrapped by the coated polyester fabric presents a higher temperature compared with bare polyester fabric, in simulated cold conditions. Meanwhile, in heating conditions, the internal temperature of the coated polyester fabric is 5.2 oC lower than that of the bare polyester fabric. Furthermore, the coated polyester fabric exhibits excellent flame retardancy in the combustion test, with a horizontal burning rate of 85.7 mm/min and a peak of heat release rate (PHRR) reduction of 52.8 %, attributed to higher graphitization degree and suppressed pyrolysis products. For promoting the practical application, the water vapor transmission, washing resistance, and mechanical performance are also deeply studied. Hence, a phase-change flame-retardant polyester fabric constructed with a host–guest structure provides huge application potentials in various personal temperature management fields, such as snow rescue, field camping, and adventure activities.

Mechanical properties and flammability of pineapple leaf fiber (PALF) reinforced polymer composite with hybridized fire retardants

Natural fibers are notorious for their low fire resistance due to the cellulose present in plant fibers and hydrocarbon-based polymers, which make the compounds highly flammable. Various hybridized fire-retardant additives are used in Pineapple Leaf Fiber (PALF) reinforced polymer composites, namely magnesium hydroxide/ammonium polyphosphate (MH/APP), aluminum hydroxide/ ammonium polyphosphate (ALH/APP), each at different percentages of fire retardants (10 wt%, 20 wt%, and 30 wt%). Underwrites Laboratories 94 (UL-94) was used for the fire retardancy test, while a Universal Testing Machine (UTM) was used for the flexural test to evaluate mechanical properties. Scanning Electron Microscopy (SEM) was employed to observe the surface morphology of the samples. The hybridized additive sample MH/ALH at 30% exhibited a higher average flexural strength of 107.47 MPa in the mechanical properties of the PALF-reinforced polymer composite. Moreover, the sample MH/APP at 30% stands out as the best hybridization additive, exhibiting a burning rate of 10.83 mm/min in the horizontal burning test. The hybridization of MH and APP led to increased char formation during combustion. Additionally, in the vertical burning test, all samples burned completely.

Fully bio-based fire-safety composite from cotton/viscose wastes and alginate fiber as furniture materials

The increasing demand of textiles and apparel as global economy booms deepens environmental crisis associated with excessive textile waste disposed by landfill or incineration. This work implemented an eco-friendly and sustainable strategy to recycle up to 50 wt% textile waste with marine bio-based calcium alginate fiber into fire-proof fully bio-based composite textile by carding process. Incorporation of intrinsic nonflammable calcium alginate fibers endowed these needle-punching bio-composite felt with excellent inherent flame retardancy and improved safety. Horizontal burning test showed that by mixing with alginate fiber in proper ratio and pattern, extremely flammable cotton fiber and viscose fiber became totally inflammable. Analysis revealed that the generation of CaCO3 char residue and gaseous volatile of H2O inhibited the diffusion of O2 and heat, contributing to the outstanding fire proof performance of produced composite felt. The improved safety was affirmed by cone calorimetry test. It demonstrated limited heat, smoke and toxic volatile compound in the burning, as well as production of CO and CO2. All results showed that a straightforward yet economical method could recycle textile waste fibers into fully bio-based, fireproof and greener products, a potential candidate as fireproof structural filling and insulation materials for household textile or construction material.

Synergistic Adenosine Triphosphate/Chitosan Bio-coatings on Polyurethane Foam for Simultaneously Improved Flame Retardancy and Smoke Suppression

Considering that fire safety is a persistent problem for most polymeric materials, including polyurethane (PU) foam, the demand for flame retardants (FRs) is growing. However, the use of conventional FRs containing halogenated and brominated chemicals has been continuously regulated owing to their toxicity. Here, we demonstrate the layer-by-layer (LbL) coating of negatively charged adenosine triphosphate (ATP) and positively charged chitosan (CS) as the synergistic FR on PU foam, a model flammable polymer material. The FR performance of the PU coated with LbL-assembled ATP and CS (ATP/CS-PU) was tested, and the results suggested that the ATP/CS layers were finely deposited on the surface of the PU without damaging the structure. Only five bilayers (5BL) were sufficient to impart excellent fire retardancy, which exhibited a limiting oxygen index value of 35% and the HF-1 rating in the UL94 foamed material horizontal burning test. In addition, ATP/CS(5BL)-PU showed a significant reduction in the peak heat release rate of 42.0% and in the total smoke release of 30.6% compared to that of bare PU (b-PU). Furthermore, the ATP/CS coatings did not deteriorate the mechanical properties of b-PU. Finally, combined thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) showed that ATP/CS(5BL)-PU was safe because it suppresses hazardous gases, which is the main problem with conventional FRs.

Flexural and flame retardance properties of multi-walled carbon nanotubes/glass fibre/epoxy hybrid composites

The effect of different multi-walled carbon nanotubes (MWCNTs) wt.% loading on the flammability, water absorption, thermal stability and flexural properties of glass fabric reinforced epoxy composites is reported in this paper. The pristine MWCNTs were dispersed in water, using arabic gum (GA) as a dispersing agent. Then, the suspension was sprayed onto the glass fibre (GF). Hybrid composites with and without MWCNTs were fabricated using hand lay-up and vacuum bagging techniques. Based on standard fire testings such as limiting oxygen index (LOI) and horizontal burning (UL94HB), it was observed that the composites were able to self-extinguish, even at low amounts of MWCNTs. Increase in the MWCNTs content produced a concurrent increase in the LOI of the composites which reached a maximum value of 31.30 ± 1.22% at 1 wt% MWCNT. The thermal stability was investigated using thermogravimetric analysis (TGA) and it was found that the addition of MWCNTs improved thermal stability, and increased the fire-retardance of the glass fabric reinforced epoxy (GF/EP) composites. The highest composite flexural strength (150 MPa) and flexural modulus (12 GPa) were attained at 0.5 wt% MWCNT. Above 0.5 wt%, a drop in strength and modulus was observed. The results from this study showed that the use of hybrid reinforcement containing MWCNTs can help to significantly improve the flame retardance, water absorption, and mechanical properties of reinforced composites by incorporating optimum amount of MWCNTs.