Intumescent Flame Retardant Coatings Research Articles

Smoke Suppression Properties of Fe2O3 on Intumescent Fire-Retardant Coatings of Styrene–Acrylic Emulsion

The intumescent flame-retardant coatings were prepared using ammonium polyphosphate (APP), pentaerythritol (PER), melamine (MEL), styrene–acrylic emulsion, and iron oxide yellow (FeOOH) as the base material. A cone calorimeter (CCT), smoke density meter (SDA), and scanning electron microscope (SEM) were employed to investigate the smoke suppression and flame retardancy of FeOOH in intumescent fire-retardant coatings. The thermal degradation performance of intumescent fireproofing coatings with varying FeOOH content was investigated through thermogravimetric analysis (TGA). The structure of the carbon slag in the CCT test was analyzed using a scanning electron microscope (SEM). The results of the cone calorimeter (CCT) experiments demonstrated that FeOOH significantly reduced the heat release rate (HRR), total heat release rate (THR), smoke production rate (SPR), and total smoke release rate (TSR) of the coating, while simultaneously increasing the carbon residue rate of the coating. The smoke density analysis (SDA) results demonstrate that adding FeOOH can effectively reduce smoke generation, regardless of whether a pilot flame is used. TGA results demonstrate that FeOOH can enhance the weight of coke residue at elevated temperatures. SEM results indicate that incorporating FeOOH resulted in a more compact coke residue. According to these findings, among all the samples, those containing 2 wt% FeOOH showed low levels of HRR, THR, SPR, and TSR and high levels of SOD, which proves that FeOOH can be used as a smoke inhibitor in flame-retardant coatings.

Development of test methods for fire-retardant coatings of steel engineering structures during operation

Introduction. Prediction of the durability of flame-retardant coatings of steel engineering structures and preservation of their performance during operation remain important research directions. There is a lack of normative documents in the field of fire protection, regulating the process of testing of flame-retardant coatings during operation, as well as determination of their durability (service life).Aim. To develop test methods for determining the resistance of flame-retardant coatings of steel engineering structures exposed to climatic factors, preservation of their fireproof and anti-corrosion properties during operation.Materials and methods. Test specimens included 600 x 600 x 5 mm plates made of 08kp and 08ps sheet steel according to State Standard 16523-97 and State Standard 9045-93 with a flame-retardant agent applied on the front side.Results. Methods for testing thin-layer intumescent and structural flame-retardant coatings during operation are proposed. The methodology of accelerated climatic testing of specimens coated with thin-layer intumescent flame-retardant coatings (flame-retardant paints) corresponds to State Standard 9.401-2018. These coatings are inherently high-solid paint materials. A new methodology, sequence, and modes of testing are developed for structural flame-retardant coatings. The subsequent assessment of fireproof properties of coatings and their preservation is carried out by the methods of fire protection efficiency according to State Standard R 53295-99 and the methods of thermal analysis. These methods imply comparison of the characteristics of the initial flame-retardant coating and those obtained after sample aging. The preservation of fireproof properties by thin-layer intumescent and structural coatings is additionally evaluated by the intumescence coefficient and the change in thermal conductivity, respectively.Conclusions. Test methods for flame-retardant coatings of steel engineering structures during operation are developed. Threshold levels of changes in their properties are established. After accelerated climatic tests, fire protection efficiency should not decrease by no more than 20 %. For structural fire protection, an increase in thermal conductivity by no more than 5 % is permitted. For thin-layer coatings, the arithmetic mean value of the intumescence coefficient should not decrease by no more than 30 % of the initial value.Implications. The developed methods were used in the preparation of a draft national standard of the Russian Federation “Steel engineering structures with fireproof coatings. Test methods for anticorrosion properties and resistance to climatic factors during operation” to ensure regulatory fire safety requirements for these structures.

P/N/Si-rich and flexible coating imparting polypropylene excellent flame retardancy without compromising its inherent mechanical properties

In general, the addition of flame retardants may lead to the degradation of the mechanical properties of polymers, despite enhancing their flame retardancy. However, flame-retardant coatings have the potential to provide good flame resistance to polymers without compromising their inherent mechanical properties. In this study, we applied highly adhesive and flexible polysiloxane flame-retardant coatings (196 μm) to polypropylene, resulting in reductions of 74.9 %, 58.0 %, 80.0 %, and 56.4 % in peak heat release rate, peak smoke production rate, fire growth rate, and mass loss, respectively. By incorporating the lab-synthesized DOPO-modified polysiloxane (APID), the flame-retardant efficiency of ammonium polyphosphate (APP) was greatly enhanced. The primary film-forming agent, (3-aminopropyl) triethoxysilane (APTES), played a key role in maintaining the compatibility of APP and APID with the coating, as well as facilitating the formation of a robust SiOSi crosslinked network structure that strengthened the resulting char layer. The interactivity between the various components, including hydrogen bonds and crosslinked network structures, contributed to improved uniformity, thermal stability, and adhesion of the coatings. Moreover, the coatings exhibited resistance to ultraviolet radiation and water. Our findings suggest that highly flexible and adhesive flame-retardant coatings hold significant potential for applications in polymer protection. These promising results provide a viable pathway for improving the fire protection of polymers through the use of high-adhesive intumescent flame-retardant coatings.

The Effect of Different Diluents and Curing Agents on the Performance of Epoxy Resin-Based Intumescent Flame-Retardant Coatings.

The epoxy resin-based (ESB) intumescent flame-retardant coatings were modified with 1,4-butanediol diglycidyl ether (14BDDE) and butyl glycidyl ether (BGE) as diluents and T403 and 4,4'-diaminodiphenylmethane (DDM) as curing agents, respectively. The effects of different diluents and curing agents on the flame-retardant and mechanical properties, as well as the composition evolution of the coatings, were investigated by using large-plate combustion, the limiting oxygen index (LOI), vertical combustion, a cone calorimeter, X-ray diffraction, FTIR analysis, a N2 adsorption and desorption test, a scanning electron microscope (SEM), a tensile strength test, and a viscosity test. The results showed that the addition of 14BBDE and T403 promoted the oxidation of B4C and the formation of boron-containing glass or ceramics, increased the residual mass of char, densified the surface char layer, and increased the specific surface area of porous residual char. When their dosage was 30%, ESB-1T-3 coating exhibited the most excellent flame-retardant properties. During the 2 h large-plate combustion test, the backside temperature was only 138.72 °C, without any melting pits. In addition, the peak heat release rate (PHRR), total heat release rate (THR), total smoke production (TSP), and peak smoke production (PSPR) were reduced by 13.15%, 13.9%, 5.48%, and 17.45%, respectively, compared to the blank ESB coating. The LOI value reached 33.4%, and the vertical combustion grade was V-0. In addition, the tensile strength of the ESB-1T-3 sample was increased by 10.94% compared to ESB. In contrast, the addition of BGE and DDM promoted the combustion of the coating, affected the ceramic process of the coating, seriously affected the formation of borosilicate glass, and exhibited poor flame retardancy. The backside temperature reached 190.93 °C after 2 h combustion. A unified rule is that as the amount of diluent and curing agent increases, the flame retardancy improves while the mechanical properties decrease. This work provides data support for the preparation and process optimization of resin-based coatings.

Preparation of waterborne intumescent flame-retardant coatings using adenosine-based phosphonates for wood surfaces

Here, organic solvent-free adenosine-based waterborne flame retardant curing agents were synthesized and introduction into a melamine urea-formaldehyde resin (MUF) to construct flame-retardant coatings for wood surfaces. Adenosine-based phosphonate (APU), composed of adenosine, urea, formaldehyde, and phosphorous acid, was synthesized by the Mannich reaction. The chemical structure of APU was investigated by Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and 31P nuclear magnetic resonance (NMR) spectroscopy. In contrast to MAW0, the coatings containing APU exhibited similar physical characteristics. MAW4 achieved a vertical combustion (UL-94) V-0 rating and an impressive limiting oxygen index (LOI) of 54.5 %. Cone calorimetry indicated that the time to ignition (TTI) of MAW4 was 89 s, an increase of 790 % compared with MAW0, which may significantly prolong the escape time from a fire. Scanning electron microscopy (SEM), thermal infrared imaging, and Raman spectroscopy all confirmed that continuous and dense char layers reduced the transport of heat, ignitable gases, and smoke. This limited the further pyrolysis and combustion of wood, showing that the waterborne intumescent flame-retardant coatings proposed in this research endowed wood with excellent flame retardancy.

Preparation of acrylic emulsion coating with melamine polyphosphate, pentaerythritol and titanium dioxide for flame retardant cotton/polyethylene terephthalate blend fabrics

An organic phosphorus-nitrogen containing flame retardant melamine polyphosphate (MPP) was synthesized with two-step approach using melamine and phosphoric acid, and characterized through Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance analysis. The intumescent flame retardant (IFR) coatings were prepared using MPP, pentaerythritol (PER) and anatase-type TiO2 as FR additives and acrylic emulsion as a binder, and applied to cotton/polyethylene terephthalate (C/T) blends. The vertical flame and cone calorimeter tests were carried out to measure after-flame time, damaged length, limiting oxygen index and peak heat release rate, confirming the good flame retardancy being enhanced with increasing the content of TiO2 in the coatings. The scanning electron micrography images showed formation of numerous pores and voids on the C/T blend samples treated with only MPP and PER while the formation of compact and dense char layer with no void by adding TiO2. Through the thermogravimetric, FTIR, and X-ray diffraction analysis, it was revealed that the three-stage degradation of MPP/PER coatings released incombustible water vapor and ammonia gas, while TiO2 could react with polyphosphoric acid to produce titanium pyrophosphate ceramic layer covering the char layer.

Surface Flame-Retardant Systems of Rigid Polyurethane Foams: An Overview

Rigid polyurethane foam (RPUF) is one of the best thermal insulation materials available, but its flammability makes it a potential fire hazard. Due to its porous nature, the large specific surface area is the key factor for easy ignition and rapid fires spread when exposed to heat sources. The burning process of RPUF mainly takes place on the surface. Therefore, if a flame-retardant coating can be formed on the surface of RPUF, it can effectively reduce or stop the flame propagation on the surface of RPUF, further improving the fire safety. Compared with the bulk flame retardant of RPUF, the flame-retardant coating on its surface has a higher efficiency in improving fire safety. This paper aims to review the preparations, properties, and working mechanisms of RPUF surface flame-retardant systems. Flame-retardant coatings are divided into non-intumescent flame-retardant coatings (NIFRCs) and intumescent flame-retardant coatings (IFRCs), depending on whether the flame-retardant coating expands when heated. After discussion, the development trends for surface flame-retardant systems are considered to be high-performance, biological, biomimetic, multifunctional flame-retardant coatings.

Flexible and Self-Powered Thermal Sensor Based on Graphene-Modified Intumescent Flame-Retardant Coating with Hybridized Nanogenerators

The number of fire events that risk human life, the economy, and the environment has significantly increased in recent years. Uncontrolled fires are one of the main causes of building collapse. Due to the high smoke concentration threshold or infrared detection temperature required to activate the fire detector, the response time is long, and the fire warning and prevention effect are not ideal. For effective monitoring and early warning of fires, an innovative fire alarm system was fabricated in this study. This system combines a highly flexible and self-powered thermal sensor (FSTS) as well as a commercial light emitting diode (LED). The FSTS is a fire-retardant sensor and very easy to install. The innovation of this paper is the hierarchical structure of the FSTS. It combines a graphene-modified intumescent flame retardant (GIFR) flame-retardant coating layer with a self-powered PVDF-based nanogenerator, which shows an innovative design in the area of fire sensors. The structure integrates poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE) micro/nano fibers (MNFs) deposited by a near-field electrospinning (NFES) process and an electrostatic friction layer by polydimethylsiloxane (PDMS) rolling over technology with a fully encapsulated GIFR coating. It can be used as a motion-induced energy harvester with a self-powered fire alarm system. The voltage output of the FSTS reaches 11.8 V, which can be easily matched with a bridge rectifier circuit to charge capacitors in daily life. The unique feature of the FSTS is that, at room temperature, the FSTS is electrically insulating; however, it conducts electricity at high temperatures. In a fire, high temperatures cause the coating to char and expand transitioning from an electrically insulating state to a conducting state. In this way, warning lights connected to the FSTS will respond within a short period (∼3 s), alerting people immediately so that urgent action can be taken.

Phytate-based transparent and waterproof intumescent flame-retardant coating for protection of wood

Phytic acid-based phosphate esters (PAPEGs) were prepared through the reaction between phytic acid (PA) and different proportions of polyethylene glycol 200 (PEG-200). Intumescent flame-retardant coating (IFRC) with PAPEG3, PAPEG6, PAPEG9 and PAPEG12 were obtained via thermal curing of PAPEGs and melamine formaldehyde resin (MFR), respectively. The backside temperature of steel with MFR/PAPEGs coating was much lower than that of MFR/PA coating. MFR/PAPEG6 coating showed the best flame retardancy, and the char thickness reached 48 mm from initial thickness of 0.4 mm, and the expansion ratio was 120 times. Cone calorimeter confirmed that the incorporation of PAPEG6 could minimize the heat release rates and total heat release of materials during combustion. Moreover, the MFR/PAPEGs coating possessed both excellent transparency and water resistance. The transmittance of MFR/PAPEG6 and MFR/PAPEG9 was above 87% at 600 nm, and transmittance of MFR/PAPEG12 even reached 90%. The proposed flame-retardant mechanism was that MFR/PAPEGs produced phosphorus-containing acids to dehydrate and carbonize PEG, leading to the formation of graphitized chars. Meanwhile, the nitrogen-containing intermediates simultaneously released noncombustible gases to expand the char and interrupt the combustion reaction.

Flame Retardant Coatings: Additives, Binders, and Fillers.

This review provides an intensive overview of flame retardant coating systems. The occurrence of flame due to thermal degradation of the polymer substrate as a result of overheating is one of the major concerns. Hence, coating is the best solution to this problem as it prevents the substrate from igniting the flame. In this review, the descriptions of several classifications of coating and their relation to thermal degradation and flammability were discussed. The details of flame retardants and flame retardant coatings in terms of principles, types, mechanisms, and properties were explained as well. This overview imparted the importance of intumescent flame retardant coatings in preventing the spread of flame via the formation of a multicellular charred layer. Thus, the intended intumescence can reduce the risk of flame from inherently flammable materials used to maintain a high standard of living.

NaOH hydrothermally treated gibbsite modified silicone acrylic emulsion-based intumescent flame-retardant coatings for plywood

The gibbsite has been employed to design hybrid flame retardants, the directly hydrothermal pretreatment could enhance its reactivity in theory. Therefore, NaOH hydrothermally pretreated gibbsite is exploited to optimize silicone acrylic emulsion (SAE)-based intumescent flame-retardant coatings (IFRC) through a facile sol-gel method, it determines that the pretreated gibbsite holds superior flame resistance to pristine gibbsite. The hydrothermal condition of 4 mol·L−1 NaOH under 100 °C facilitates the transformation from gibbsite to boehmite, leading to the formation of growing hydroxyl and irregular microstructure, corresponding to the improved flame retardancy. The doped gibbsite/boehmite imparts an enhanced flame retardancy to the SAE-based IFRC, evidenced by the highest FRI of 2.05 with an FGI of 0.28 kW·m−2·s−1 compared with that of S0 (0.62 kW·m−2·s−1). Because the enhanced crosslinking of the newly formed boehmite constitutes the compact and continuous charring with an improved flame retardancy. It explores low-carbon recycling exploitation of bauxite residue for preparing organic-inorganic hybrid flame-retarding coatings, seeking an efficient approach to improving gibbsite‘s synergistic flame-retarding effect.

Effective enhancement of intumescent flame retardant coating by coordinating manganese ions on cotton fabrics

AbstractThe intumescent flame retardant coating consisting of polyethylenimine (PEI) and poly sodium phosphate has various drawbacks including poor water durability, inferior flame retardancy, and large consumption of nonrenewable raw resources. An intumescent fire retardant coating coordinating with manganese ions was designed onto the cotton fabrics surface by a layer‐by‐layer assembly method to solve these concerns. Energy dispersive spectroscopy revealed that the coating included well‐distributed manganese ions. The thermogravimetric measurement showed that after adding manganese ions into the coating, the decomposition of treated fabrics shifted towards a lower temperature and more char residues were formed due to the catalytic effect of manganese ions. Coated cotton fabrics with manganese ions yielded the most reduction in peak heat release rate and the highest rise in char residues, up to 69.1% and 34.7%, respectively, in microscale combustion calorimeter results. Limiting oxygen index (LOI) of the samples with manganese ions was the highest, up to 28.3% and the char layer was more intact and continuous after vertical combustion test. Scanning electron microscopy analyses showed that treated cotton fabrics with manganese ions had more bubbles and char residues on the fiber surface. These findings indicated that manganese ions coordination was responsible for the catalytic and synergistic effects. Furthermore, the coating containing manganese ions exhibited better water endurance owing to high‐LOI values even after rinsing. This work shows manganese ions into intumescent flame retardant coatings improves cotton fabrics flame retardancy and water resistance.

Deterioration mechanism on flame retardancy of aliphatic waterborne polyurethane-based hybrid coatings under ultraviolet radiation: Experiment and pyrolysis kinetics

Organic-inorganic hybrid intumescent flame retardant coating (IFRC) has been manifested as a promising solution to prevent fire spread of the plywood for indoor decoration. The aliphatic waterborne polyurethane (AWP)-based IFRC is prepared using the silicon-based aerogel, β-cyclodextrin, and nano-ZnO as the functional filler, and its ultraviolet-aging deterioration mechanism on flame retardancy is investigated through microstructure characterizations and pyrolysis kinetic calculation. The results show that the flame-retarding and smoke-suppressing properties of the IFRC gradually deteriorate with the prolonged ultraviolet exposure from 6 to 60 cycles, evidenced by the reduced flame retardancy index of 0.19 (drops from 1.00), the rising fire growth index from 0.87 to 1.45 kW m −2 s −1 , the increased average effective heat of combustion from 3.45 to 5.65 MJ·kg −1 , and the rising total smoke production from 91 to 153 m 2 . Because the ultraviolet radiation favors the chain scission of AWP and cleavage of –HN-CO-, crystallization of Zn 3 (PO 4 ) 2 , ZnP 4 O 11 , and SiP 2 O 7 for the IFRC during burning, leading to the reduced E α of 330–150 ℃ (decreases by 20%) approximately, presenting a reduced water contact angle and a fluffy char. It preliminary seeks the ultraviolet-aging flame-retarding mechanism with quantitative techniques and explores the condensed flame-retarding mechanism further. • Ultraviolet-aging deterioration mechanism of hybrid IFRCs is quantitatively investigated. • The ultraviolet radiation favors the crystallization of Zn 3 (PO 4 ) 2 , ZnP 4 O 11 , and SiP 2 O 7 . • The ultraviolet radiation contributes to the E α of 330–150 ℃ decreased by 20% approximately.

Benign design intumescent flame-retarding aliphatic waterborne polyester coatings modified by precipitated silica aerogel and aluminum powder

The organic-inorganic hybrid intumescent flame retardant coatings (IFRCs) is an efficient and ecological strategy to obtain excellent fireproof performance. The benign design on aliphatic waterborne polyester (AWP)-based IFRCs is modified by silicon-based aerogels and aluminum powder simultaneously, which is characterized by various techniques to explore the flame retardant mechanism. The results show that an appropriate precipitated silica aerogel (0.45 wt%) and aluminum powder (0.8 wt%) impart synergetic flame-retarding and smoke suppression effect to the AWP-based IFRCs, evidenced by the reduced fire growth index of 0.50 from 0.63 kW m−2 s−1, as well as the raised flame retardancy index of 2.52 from 1. Because the labyrinth barrier effect of amorphous silica-alumina gels derives from the in-situ cross-linking between the active Si(OH)4 and AlOOH or Al(OH)3, as well as the enhanced adhesive property between silanols and plywood surface, which facilitates the ceramic-like charring of AWP-based IFRCs, leading to the formation of continuous and tortuous char. It expands the design methods and flame-retarding mechanism of ecological organic-inorganic hybrid IFRCs.

Investigation of the Effect of Fillers on the Properties of the Expanded Coke Layer of Epoxyamine Compositions

Intumescent fire-retardant coatings based on epoxy resins, compared to traditional fire-retardant compositions, have improved performance properties – high strength, chemical and atmospheric resistance, adhesion to many materials. However, unmodified epoxy polymers are combustible and to obtain IFR based on them, flame retardants and mineral fillers are added to their composition. Intumescent systems for flame retardant coatings based on epoxy oligomers (non-halogen-containing) usually consist of ammonium or ammophos polyphosphate as an acidic agent and a wide range of fillers, both inert and gaseous, or which are an additional source of carbon. Each component of the fire-retardant intimate coating in different ways affects the processes of coke formation, which determines the requirements for their choice. Thus, the aim of this work is to conduct experimental studies of the dependence of the characteristics of the expanded coke layer on the composition of the intumescent epoxyamine composition. The results of experimental studies of the effect of ammonium polyphosphate and binary mixtures of ammonium polyphosphate (APP) with aluminum hydroxide (AH), sodium tetraborate decahydrate (STD), titanium oxide TiO2 (TO), pentaerythritol (P), aerosil (A) and expandable graphite are presented (EG) on the multiplicity of expanding and weight loss of epoxy compositions at study temperatures of 350, 400 and 450°C. Studies have shown that the production of intumescent flame retardant coatings based on epoxy oligomers is possible provided they are filled with ammonium polyphosphate in an amount of more than 20 mass parts. The most effective in terms of expanding are additives titanium oxide and aluminum hydroxide in an amount of 20 mass parts, which allows to obtain intumescent fire-retardant coatings with a linear coefficient of expanding 30-32 and 24-27, respectively, throughout the range of temperatures. The obtained data are useful in the development of fire-retardant coatings based on epoxy oligomers.

The Evolution of Intumescent Char in Flame-Retardant Coatings Based on Amino Resin

Intumescent flame-retardant (IFR) coatings have been gaining more attention. The behaviors of intumescent char in IFR coatings play the most important role in its flame-retardant properties. However, the evolution of intumescent char throughout the whole process of protection is still unclear. In this study, both the formation and shrinkage of char were studied. The formulation of IFR includes melamine modified urea-formaldehyde resin (MUF), ammonium polyphosphate (APP) and pentaerythritol (PER). The flame-retardant properties of the coating were measured by the cone calorimeter (CONE). The evolution of the volume and the pore size distribution of char were monitored. The morphological and chemical structures were characterized by the scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results show that the evolution of intumescent char could be divided into three stages. More than 50% shrinkage of char occurs in the second stage. There are obvious transformations of the morphological and chemical structures of char between the different stages.

Role of Copper Oxide on Epoxy Coatings with New Intumescent Polymer-Based Fire Retardant.

Epoxy resins (EP) have been used as a thermos-setting material in the field of coating, casting, bonding agent, and laminating. However, a major drawback associated with its use is the lack of good flaming properties, and it is responsible for heavy smoke along with hazardous gases considerably limiting its uses in various fields. In this study, N-ethanolamine triazine-piperizine, a melamine polymer (ETPMP), was established as a new charring-foaming agent and was successfully synthesized with ethanolamine, piperizine, cyanuric chloride, and melamine as precursor molecules via the nucleophilic substitution reaction method. Elemental analysis and Fourier transform infrared (FTIR) spectroscopy analysis were applied to approve the synthesis of ETPMP and confirmation of its structure and characterization. The epoxy coating of intumescent flame retardant (IFR) was equipped by introducing ETPMP, ammonium polyphosphate (APP), and copper oxide (CuO) in multiple composition ratios. CuO was loaded at various amounts into the IFR-coating system as a synergistic agent. The synergistic action of CuO on IFR coatings was scientifically examined by using different analytical tests such as vertical burning test (UL-94V), limited oxygen index (LOI), thermal gravimetric analysis (TGA), cone calorimeter, and scanning electron microscope (SEM). The results showed that small changes in the amount of CuO expressively amplified the LOI results and enhanced the V-0 ratings in the UL-94V test. The TGA data clearly demonstrate that the inclusion of CuO can transform the thermal deprivation behavior of coatings with a growing char slag proportion with elevated temperatures. Information from cone calorimeter data affirmed that CuO can decrease the burning factors by total heat release (THR) together with peak heat release rate (PHRR). The SEM images indicated that CuO can enrich the power and compression of the intumescent char that restricts the movement of heat and oxygen. Our results demonstrate a positive influence of CuO on the epoxy-headed intumescent flame retardant coatings.

Investigation of Aluminate Coupling Agent as Modifier and Its Application on Improving Flame Retardant of Intumescent Flame Retardant Coatings

Intumescent flame retardant coating modified by aluminate coupling agent were prepared via sol-gel method using ammonium polyphosphate, Polyacrylamide, aluminate coupling agent (ACA), and boron nitride (BN). The effect of modification of ACA on its flame retardant and characterization were preliminarily studied by cone calorimeter, scanning electron microscope, surface tensiometer and contact angle measurement. It is found that the addition of ACA can increase the expansion rate of carbon layer, and a stronger blocking effect can lead to a better property of flame retardant. The sample containing BN, after being modified by 3M NaOH and ACA, dramatically decreases heat release rate, especially reduce the peak heat release rate (pHRR) by 54% and total heat release by 16%, respectively. Moreover, the time to ignition was delayed by 175%. Through examining the residues and pyrolysis products of the coating samples, the mechanism of enhanced flame retardant that promotes the char-forming and heat barrier of the modification of ACA and BN is proposed. This work can offer a significant guide for further studying of ACA and modified BN on the flame retardant.

Influence of Magnesium Aluminate Nanoparticles on Epoxy-Based Intumescent Flame Retardation Coating System

Ethylenediamine modified ammonium polyphosphate (EDA-MAPP) and charring-foaming agents (CFA) were prepared using a simple chemical method and further used to make intumescent flame retardant coatings based on epoxy resin. The content of MAPP and CFA was fixed at a ratio of 2:1. Nanoparticles of magnesium aluminate (MgAl2O4 NPs) have been introduced into the flame retardant coating formulation in various quantities to evaluate the promotional action of MgAl2O4 NPs with a flame retardant coating system. The promotional action of MgAl2O4 NPs on the flame retardant coating formulation was studied using a vertical burning test (UL-94V), limiting oxygen index (LOI), thermogravimetric analysis (TGA) and Fourier transform infra-red spectroscopy (FTIR). The UL-94V results indicated that the addition of MgAl2O4 effectively increased flame retardancy and met the V-0 rating at each concentration. The TGA results revealed that the incorporation of MgAl2O4 NPs at each concentration effectively increased the thermal stability of the flame retardant coating system. Cone-calorimeter experiments show that MgAl2O4 NPs effectively decreased peak heat release rate (PHRR) and total heat release (THR). The FTIR results indicated that MgAl2O4 NPs can react with MAPP and generate a dense char layer that prevents the transfer of oxygen and heat.

New pivot for investigating flame‐retarding mechanism: Quantitative analysis of zinc phosphate doped aliphatic waterborne polyurethane‐based intumescent coatings for flame‐retarding plywood

The quantitative analysis of zinc phosphate (ZnP) on the flame resistance of intumescent flame retardant coatings (IFRCs) is presented including cone calorimeter (CC) and pyrolysis kinetics, using aliphatic waterborne polyurethane (AWP) as the coating binder. The CC results show that an appropriate dosage (2 wt%) of ZnP in the AWP‐based coating constitutes an improved flame resistance, evidenced by the fire performance index increased from 0.41 to 0.71 seconds m2 kW−1, as well as the reduced fire growth index. The characterization analysis determines the dehydrated ZnP facilitates the formed amorphous char‐residue with a heat‐sink effect, leading to an increase in heat absorption, which climbs from the 253.00to 351.30 J·g−1. Besides, the pyrolysis kinetics verifies that the 3D Jander model (n = 2) mainly governs the whole pyrolysis process of pure coatings by the modified Coats‐Redfern integral method. The ZnP‐containing coating exerts an improved Eα corresponding to 95–200°C, which climbs from 24.96 to 35.80 kJ mol−1, leading to the formation of a continuous and compact char layer. It explores an effective quantitative analysis of the flame resistance of organic–inorganic hybrid IFRCs, deepening the flame‐retarding mechanism.