Fire-resistant Polymer Research Articles

Generalized nomogram for determining the type of structure and composition of fire-resistant polymer composite materials with fire-retardant fillers

A generalized nomogram for designing the type of structure and compositions of dispersion-filled polymer composite materials (DFPCM) with flame retardant fillers having high combustion resistance and a high oxygen index (OI) is proposed on the example of polymer composite based on ethylene-vinyl acetate copolymer (EVA) and magnesium hydroxide of EcoPyrene brand. The nomogram combines into a single whole the previously obtained dependencies for the calculation and organization of different types of structure of DFPCM and data on combustion resistance and OI values.

Polytetrafluoroethylene (PTFE) burn characteristics and toxicant formation in an oxidizer cross-flow via laser absorption tomography

A two-dimensional solid-fuel combustion experiment for fire-resistant polymers under forced convective cross-flow was developed to assess burn characteristics and toxicant formation using advanced laser absorption diagnostics that enable in situ species and temperature measurements near the fuel surface. The method was used to examine the thermochemical flow-field structure near the surface of polytetrafluoroethylene (PTFE) exposed to a well-defined solid-fuel pilot flame burning polymethyl methacrylate (PMMA). Infrared diode and quantum cascade lasers were used to probe rovibrational absorption transitions of hydrogen fluoride (HF) and carbon monoxide (CO), respectively, at the exit plane of a heterogeneous cylindrical fuel grain from which temperature and mole fraction could be inferred. A laser absorption tomography (LAT) technique with a Tikhonov-regularized Abel inversion was applied to reconstruct radially-resolved profiles in the axisymmetric reacting flow which, when compiled across a range of fuel lengths, provided a two-dimensional image of the near-surface reaction layer. Thermochemical data and reaction rate parameters from existing fluorocarbon chemistry models were used to generate high-temperature simulations of product species concentrations and temperature as a function of oxidizer-to-fuel ratio to elucidate observed trends and identify key reactions relevant to the novel dataset. The geometry and scale of the composite fuel experiments is intended to be tractable for reactive multi-physics models, enabling quantitative comparison of combustion characteristics and ultimately improved predictive capability of toxicant quantities resulting from fluoropolymer combustion in fire environments.

A novel macromolecular phosphorus-nitrogen containing flame retardant for polycarbonate

In this paper, an innovative macromolecular phosphorus-nitrogen containing flame retardant (PDPSB) was successfully designed and synthesized to investigate its impact on the flame retardancy, burning behavior, thermal stability, mechanical properties of polycarbonate (PC) composites. Furthermore, an in-depth exploration of the potential flame-retardant mechanism was conducted. The combustion results indicated that PC-3 with 3 wt% PDPSB reached V-0 rating in UL-94 test and showed a high limiting oxygen index (LOI) of 33.0 %. Compared to pure PC, the values for peak of heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) of PC-3 were decreased by 37.9 %, 11.1 % and 4.9 %, respectively. It was noteworthy that the amount of char residue for PC-3 was raised from 7.4 % for pure PC to 15.8 % with increasing 113.5 %. The thermogravimetric analysis (TGA) results under N2 atmosphere revealed that PDPSB possessed preferable thermal stability with initial decomposition temperature (Tinitial) of 342.6 °C and higher char residue yield of 48.4 %. With increasing the amount of PDPSB, the maximum mass loss rate (Rpeak) was reduced and the char residue yield was increased for PC/PDPSB composites. In addition, the mechanical properties of PC/PDPSB composites were well maintained due to the good compatibility and dispersion between PDPSB and PC matrix. The tensile, flexural and izod impact strength of PC-3 were weakened by 4.3 %, 1.7 % and 16.8 % in comparison of pure PC, respectively. Based on the investigation into the flame-retardant mechanism of PDPSB, the excellent flame retardance of PC/PDPSB composites has been validated. In gaseous, the release of pyrolysis gases was suppressed and active radicals were captured by generated phosphorus free radicals. In condensed phase, the stable char residue with phosphorus and nitrogen elements acted as a barrier to hinder heat, flame and oxygen. This high-efficient single-component multifunctional additive presented a novel approach to the development of fire-resistant polymers with enhanced performance characteristics.

Heat-resistant binders based on oligomeric organosilsesquioxanes

The influence of the phase state of the reaction system and the HCl concentration during hydrolytic polycondensation of methyltrichlorosilane on the composition of the formed oligomers, their stability during storage and ability to thermal curing is shown. The technological production process is developed and the scheme of a pilot plant for obtaining oligomethylsilsesquioxanes used for the production of highly filled thermo- and fire-resistant polymer composite materials is presented.

Functionalizing MXene towards highly stretchable, ultratough, fatigue- and fire-resistant polymer nanocomposites

Thermoplastic polyurethane (TPU) features many important industrial applications, but intrinsic flammability extremely impedes its practical applications. Current fire-retardant strategies often lead to improved flame retardancy but reduced mechanical properties (strength, ductility, and toughness). Hence, to date it has been unsuccessful to design advanced TPU materials that are strong, stretchable, tough, fatigue-and fire-resistant to meet increasing performance portfolio requirements. Here, we report a hybridized fire retardant (Zr-MXene) by in situ facilely loading zirconium amino-tris-(methylenephosphonate) (Zr-AMP) onto the titanium carbide (MXene) surface. Our results show that with 1 wt% of Zr-MXene, the resultant TPU nanocomposites demonstrate a record break strain (2060%) and toughness (316 MJ/m3) to date, in addition to increased tensile strength by 43.4% and improved fatigue resistance relative to the TPU matrix, because of favorable interfacial hydrogen-bonding. Moreover, the resultant TPU material exhibit significantly reduced flammability as a result of the combined physical barrier, catalytical carbonization and diluting effects of Zr-MXene. This work provides a promising strategy for the creation of multifunctional MXene and its polymeric nanocomposites, which hold great promise for many industrial applications.

Ionic liquid-based molecular design for transparent, flexible, and fire-retardant triboelectric nanogenerator (TENG) for wearable energy solutions

Transparent and flexible triboelectric nanogenerator (TENG) represent an efficient and invisible energy solution for generating eco-friendly electricity from mechanical human motion for wearable electronic devices and systems. In addition to boosting the output performance of TENG, the molecular design relying on non-flammable materials and anti-ignition invulnerability should be considered when designing TENG devices, to ensure the safety of personnel working under extreme temperature conditions. However, the requirement for non-flammability of conventional transparent triboelectric materials in wearable applications remains either unmet or almost unexamined to date. Here, we propose bi-continuous and flame-retarding epoxy-based ion-gel films that retain mechanical flexibility, optical transparency, and fast ionic polarization for high-performance and deformable TENG. It is found that our transparent and flexible TENG devices produce an output voltage and current as high as approximately 150 V and 45 μA, respectively, from an external mechanical stimulus while also retaining their fire retardancy and low flammability. This TENG is not flammable even after 20 s of trying, whereas conventional triboelectric materials were completely burned by the fire under the same conditions. Therefore, we propose that our synergistic design of triboelectric ion-gel films, including fire-retardant epoxy-based dual cation-incorporated ionic liquid, represents a significant step toward a high-performance, durable, and transparent wearable energy solution. A new type of ionic liquid-based molecular design for our TENG device structure containing dual-positive ions and forming the electrical double layer (EDL) due to the rapid movement of internal ions during friction. It was intended that the dual ILs including Li+ and EMIM+ positive ions can easily transport through the bi-continuous structure of fire-resistant polymer backbone upon the mechanical surface friction as depicted in the right image. • Ionic liquid-based molecular design for high-performance and mechanically durable TENG film. • Flame-retarding, transparent and flexible epoxy-based ion-gel films. • Transparent and flexible triboelectric nanogenerators (TENGs) producing an output voltage and current of ~150 V and ~45 μA from an external mechanical stimulus.

INFLUENCE INORGANIC FILLERS ON THE PROPERTY OF POLYMER COMPOSITION BASED ON EPOXY RESIN ED-20

There were results of research on the influence of inorganic filler of tungstate on the curing process, stress-strain properties and fire resistance of polymer composition based on epoxy resin ED-20 cured by polyamine in this paper. It's showed on the increase physical-mechanical property and fire resistant polymer compositions incorporated tungstate.

INFLUENCE INORGANIC FILLERS ON THE PROPERTY OF OLIGOMER-POLYMER COMPOSITION

There were results of research on the influence of inorganic filler of tungstate on the curing process, stress-strain properties and fire resistance of oligomer-polymer composition based on epoxy resin ED-20 with PVC cured by polyamine in this paper. It's showed on the increase physical-mechanical property and fire resistant polymer compositions incorporated tungstate.

Flame-retardant PNIPAAm/sodium alginate/polyvinyl alcohol hydrogels used for fire-fighting application: Preparation and characteristic evaluations

A novel fire-preventing triple-network (TN) hydrogel was prepared and laminated on cotton fabric to improve fire-resistant performance of cellulose fabric. The TN hydrogel composed of Poly (N-isopropylacrylamide) (PNIPAAm)/sodium alginate (SA)/ Poly (vinyl alcohol) (PVA) exhibited excellent swelling ratio, swelling-deswelling behavior and antibacterial property. Results indicated that introduction of SA could improve water retention capabilities of TN hydrogels. Thermogravimetric experiments showed that the thermal stability of hydrogels was best at a SA: PVA ratio of 2:1. Furthermore, the obtained hydrogel-cotton fabric laminates displayed efficient flame retardancy. Compared to original fabric, hydrogel-fabric laminates were nearly undamaged when exposed to fire for 12 s. This result is attributed to energy absorption as water is heated and evaporates in the hydrogel. The present work provides a new concept to prepare fire-resistant polymer fabric, which may be used in fire-protective clothing to protect the skin from burn injuries.

Flexible, Self-Healing, and Fire-Resistant Polymer Electrolytes Fabricated via Photopolymerization for All-Solid-State Lithium Metal Batteries.

The cyclophosphazene-based self-healing polymer electrolytes (CPSHPE) is designed and fabricated via the copolymerization of hexa(4-ethyl acrylate phenoxy) cyclotriphosphazene (HCP), (2-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)ureido)ethyl methacrylate) (UPyMA), and poly(ethylene glycol) methyl ether methacrylate (PEGMA) under UV irradiation. The cross-linking structure formed by HCP could effectively enhance the mechanical strength of the polymer electrolyte, and the cyclotriphosphazene as the core is able to improve the flame-retardant properties. Benefiting from the phenyl groups in HCP and the cross-linking structure, the CPSHPE shows high thermal stability (up to 300 °C). On the other hand, the supramolecular network fabricated by the dynamic ureido-pyrimidinone (UPy) dimers endows the polymer electrolyte with good self-healing capability and is expected to improve the reliability of polymer lithium batteries. Moreover, the cells were fabricated with LiFePO4 (LFP), CPSHPE, and Li anodes show good reversible specific capacity. The CPSHPE could be a promising candidate as the multifunctional polymer electrolyte to improve the safety performance of lithium metal batteries.

Interband cascade laser absorption of hydrogen chloride for high-temperature thermochemical analysis of fire-resistant polymer reactivity.

A mid-infrared absorption spectroscopy technique has been developed to quantitatively and spatially resolve gas temperature and molecular abundance of $ ^1{{\rm H}^{35}}{\rm Cl} $1H35Cl in the high-temperature pyrolysis and oxidation layers of chlorinated polymers. Two transitions in the R-branch of the fundamental vibrational band of HCl near 3.34 µm are selected due to their relative strength and spectral isolation from other combustion products at elevated temperatures, and they are probed using a distributed feedback interband cascade laser. A scanned-wavelength direct absorption method is employed with a Voigt line-fitting routine to recover projected absorbance areas across the exit plane of a cylindrical polymeric slab, wherein the gaseous core comprises the axisymmetric reaction layer. Tikhonov-regularized Abel inversion of the projected absorbance areas yields line-integrated radial absorption coefficients, from which a two-line ratio is used to infer a radially resolved temperature between the gas core and solid polymer surface. The method is demonstrated to provide insights into the gas-phase combustion physics that lead to the formation of toxicants when a fire-resistant polymer, polyvinyl chloride (PVC), is burned in the presence of oxygen. Two-dimensional images were generated by assembling multiple tomographic reconstructions for several cylinder lengths. The quantitative images highlight the technique's ability to characterize the thermochemical evolution and toxicant formation during the burning of a halogenated polymer fuel.

Influence of Fiber Length on Mechanical Properties of Paper Based on Heat Resistant and Fire-Resistant Polymer Fibers

Information on industrial paper obtained from special purpose heat-resistant and fire-resistant fibers by the method of fiber swelling is presented. Results of a study of the effect of fiber cutting length on the mechanical properties the paper are presented. Corresponding dependencies are established.

Bi-phase fire-resistant polyethylenimine/graphene oxide/melanin coatings using layer by layer assembly technique: Smoke suppression and thermal stability of flexible polyurethane foams

In an effort to achieve a high-efficient fire-resistant coating for the flexible polyurethane (PU) foams, a layer-by-layer assembly technique of polyethylenimine (PEI), graphene oxide (GO) and synthetic melanin nanoparticles (SMNPs) was constructed on the surface of PU foams. The preeminent radical scavenging capacity and high-temperature thermal stability of SMNPs enable it to be applied as a flame retardant for the subsequent coating process. Scanning electron microscope (SEM) images indicate that the as-fabricated PEI/GO/SMNPs coatings are uniformly deposited on the PU foam along the cell walls. In contrast with pure and bilayer-coated (BL-coated) PU foams, thermogravimetric analysis (TGA) reveals that the trilayer-coated (TL-coated) foam exhibits a better thermos-oxidative stability and a lower pyrolysis rate with the deposition of PEI/GO/SMNPs nanocoating. In the torch burn test, the flame of PU-1TL foam coated with only one-trilayer PEI/GO/SMNPs is able to self-extinguish and the original shape of the entire foam is intactly preserved. Cone colorimeter tests indicate that the release amount of heat and smoke can be effectively suppressed in the coated foam, and the formation of the highly graphitized char is beneficial to the improvement of the fire-resistant performance. In addition, thermogravimetric analysis/infrared spectrometry (TG-IR) results demonstrate that the volatilization of organic and toxic gases in gas phase are effectively restrained, which can be attributed to the lamellar shield of GO and radical trapping effect of SMNPs. These results illustrate that synthetic melanin material is one of the promising candidates as efficient additive in fire-resistant polymers, and the PEI/GO/SMNPs coatings play a part in gas-solid phase to improve the flame retardancy of PU foams.

Synergistic improvement of flame retardant properties of expandable graphite and multi-walled carbon nanotube reinforced intumescent polyketone nanocomposites

Flame retardant and self-extinguishing properties of composites are of importance to minimize heat release and smoke production during combustion for fire resistant polymer composites. This work presents intumescent flame retardant polyketone nanocomposites composed of multilayered expandable graphites incorporated with multi-walled carbon nanotubes. We observe a significant reduction of heat release rate, total heat release, and smoke production rate as the intumescent expandable graphites are introduced in the nanocomposites. A synergistic improvement of thermal stabilities such as high flame retardancy and self-extinguishing properties is found by adding a small amount of the carbon nanotubes in the composites, which is associated with the network formation between the carbon nanotubes and the expandable graphites, inhibiting the polymer degradation and evaporation of pyrolysis oil chars by carbonaceous chars formed during the combustion. The prediction of oxygen limited index of the expandable graphite and carbon nanotube reinforced nanocomposites is in good agreement with experimental results. Mechanical properties of the nanocomposites are investigated theoretically and experimentally to reveal the bridging effect of carbon nanotubes in the composites. We propose a possible mechanism for the synergistic improvement of the flame retardant behaviors of the nanocomposites to explain the interrelationship of thermal stabilities and network structures of the nanofillers.

Physical and flammability properties of kenaf and pineapple leaf fibre hybrid composites

Pineapple leaf fibre (PALF) was hybridized with kenaf fibre in order to achieve superior physical and flammability performance. The mixing effects of kenaf fibre and pineapple leaf fibre in phenolic composites are evaluated at various fibre ratios and investigated various physical properties such as density, void content water absorption, thickness swelling and flammability. Pure kenaf fibre composite showed lowest void content, water absorption and thickness swelling while pineapple leaf fibre revealed the opposite trend. After adding pineapple leaf fibre in kenaf composites, it absorbed more moisture and developed more void contents. Density of PALF composite was lower and kenaf fibre composite was highest but PALF/kenaf hybrid composite increased density with higher PALF. The flammability of hybrid composites were analysed by using UL-94 test method. Vertical and horizontal UL-94 test conducted to analyse fire resistance of composites from different angles. Phenolic resin is itself a fire resistant polymer and the percentage of polymer in all samples are fixed though ratios of both fibres pineapple leaf fibre and kenaf were change to analyse fire resistant of fibres and compatibility with polymers. The 70 % pineapple leaf fibre and 30 % kenaf fibre hybrid composites were very affective to improve the flammability of PALF/KF hybrid composites.

Development of fire resistant wool polymer composites: Mechanical performance and fire simulation with design perspectives

Wool, as a naturally fire resistant fibre, has been incorporated with other additives, such as ammonium polyphosphate (APP), talc and maleic anhydride grafted polypropylene (MAPP), to manufacture polypropylene (PP) based composites. A single-screw extruder, attached with a flat die, has been used to successfully produce continuous wool-PP composite sheets. Furthermore, the significant roles of nitrogen content of APP and the talc in forming the effective char to increase the composites' fire retardancy have been identified through cone calorimeter tests. In particular, it is highly interesting to note that a reduction of APP content from 20 to 15wt% was possible to achieve a direct self-extinguishment (V-0 rating) of the composite. The decrease in APP amount has also led to the reduction of material cost due to APP's relatively high price (USD 13–14/kg) and limit the possibility of deteriorating mechanical properties due to APP addition. The MAPP has enhanced thermal stability and mechanical properties compared to those without the additive, which could be attributed to the improved interfacial adhesion between wool and PP. A computational fluid dynamics model has also been developed by Fire Dynamics Simulator to mimic the cone calorimeter tests, which agreed reasonably well with the experiments.

Fire-Resistant Hydrogel-Fabric Laminates: A Simple Concept That May Save Lives.

There is a large demand for fabrics that can survive high-temperature fires for an extended period of time, and protect the skin from burn injuries. Even though fire-resistant polymer fabrics are commercially available, many of these fabrics are expensive, decompose rapidly, and/or become very hot when exposed to high temperatures. We have developed a new class of fire-retarding materials by laminating a hydrogel and a fabric. The hydrogel contains around 90% water, which has a large heat capacity and enthalpy of vaporization. When the laminate is exposed to fire, a large amount of energy is absorbed as water heats up and evaporates. The temperature of the hydrogel cannot exceed 100 °C until it is fully dehydrated. The fabric has a low thermal conductivity and maintains the temperature gradient between the hydrogel and the skin. The laminates are fabricated using a recently developed tough hydrogel to ensure integrity of the laminate during processing and use. A thermal model predicts the performance of the laminates and shows that they have excellent heat resistance in good agreement with experiments, making them viable candidates in life saving applications such as fire-resistant blankets or apparel.

Halogen-free ultra-high flame retardant polymers through enzyme catalysis

Over the past few years, the use of certain types of halogenated flame retardant additives such as decabromodiphenylether has come under intense scrutiny due to their toxicity, environmental persistence and bio-accumulation. There is an immediate need for the development of non-toxic alternative flame retardant materials and fire resistant polymers with comparable or better efficacies, obtained using benign synthetic approaches. Enzymatic polymerization is being used increasingly as an environmentally friendly alternative method for the synthesis of functional materials including polymers and additives. Here, we report a biocatalytic synthesis of a new class of thermally stable, ultra-fire resistant polyphenols based on deoxybenzoins. In calorimetric studies, these polyphenols exhibit very low heat release capacities (comparable to Nomex™) and form a large amount of carbonaceous char rendering them suitable for flame retardant applications.

Ways of providing fire safety of aviation materials

Influence of various fire-retardant additives, as well as thermostability and chemical structure on polymer flammability is analyzed, and nonfire-resistant and fire-resistant polymer materials are compared. An essential influence of these factors on flammability, smoke density, heat release rate, and limit oxygen index is shown.

Fire-resistant polymer nanocomposites based on metal oxides and hydroxides

The fire-resistant properties of polymer nanocomposites based on polyvinylchloride and nanoparticles of metal compounds were studied. The investigation of nanoparticles and the determination of their sizes were carried out using scanning electron microscopy (SEM). The size of the nanoparticles of magnesium hydroxide was equal to 50–100 nm; iron oxide, 25–50 nm; and zinc oxide, 50–100 nm. Another type of fire retardant used in the work was aminotrimethylenephosphonic acid ammonium salt (AMPAS); however, the total content of the different additives did not exceed 15%. The nanocomposites obtained were investigated by means of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC); in addition, the parameters of the oxygen index (OI) and carbon residue (CR) were measured for them. The lowest combustibility was exemplified by the composite material containing as the fire retardants a mixture of AMPAS and ZnO.