Intumescent System Research Articles

Comparison of fire resistance of polymers in intumescent coatings for steel structures

Thermal destruction of fire-retardant intumescent coating of the composition of ammonium polyphosphate (APP)/melamine (MA)/pentaerythrite (PE)/titanium oxide (TiO 2 )/polymer, which can be applied for fire protection of steel structures, was studied. The influence of polymers of different nature – ethylene-vinyl acetate (EVA), vinyl acetate versatate (VAVV), styrene acrylates, and vinyl toluene acrylate on the processes of formation of a coke layer and fire-retardant effectiveness of appropriate coatings was determined. Chemical transformations of polymers EVA and styrene acrylate in the intumescent system of ARR/MA/PE/TiO 2 in the temperature range of 200–800 °С were studied. It was established that the processes of the thermal destruction of vinyl acetate polymer are more harmonized with chemical reactions of the components of the intumescent system than similar processes for acrylate aromatic polymers. Thermal-oxidation destruction of intumescent compositions at the temperatures of 200–800 °С was explored. It was shown that basic chemical processes with polymers of EVA and VAVV begin after 300 °С and flow in the temperature range of 350–600 °С. It was found that the noticeable degradation of the carbon-phosphorus frame of intumescent compositions with styrene acrylate polymers begins at 450 °С, which is almost by 150 °С below the temperature of degradation of the compositions containing vinyl acetate binders. The conducted fire tests demonstrate that intumescent compositions with the use of acrylate aromatic polymers are more effective at the low coating thickness in ensuring the fire resistance boundary of 30 min. In order to ensure higher values of fire resistance, it is necessary to use intumescent coatings containing vinyl acetate co-polymers as the polymer component. The study of the impact of polymers of intumescent coatings on the boundary of fire resistance of steel structures has scientific and practical significance for the development of differentiated fire protection means, oriented to the given class of fire resistance. Fire-retardant intumescent compositions examined in this study can be used as the basis for the formulations of materials for fire protection of building structures under conditions of a standard fire

Intumescent coatings using epoxy, alkyd, acrylic, silicone, and silicone–epoxy hybrid resins for steel fire protection

Intumescent coatings are a great alternative for passive protection of metal substrates against fire, with binder polymer being one of the main components of an intumescent system. The objective of this work was to compare five different resin types (epoxy, acrylic, alkyd, silicone, and silicone–epoxy hybrid) in an intumescent formulation and to study the influence of resin concentration on the fire protection performance of the coating. Results from TGA and MCC analysis of resins and coatings indicated that coatings containing silicone are thermally stable and release smaller amounts of heat. In the fire resistance test, samples containing epoxy and silicone resins had lower temperatures (130–160°C) compared to the other samples. It has also been found that it is possible to decrease resin concentration in formulations containing epoxy and silicone resins up to 25.6% and to maintain or even improve their fire protection capability.

Synthesis of a novel polyhydroxy triazine-based charring agent and its effects on improving the flame retardancy of polypropylene with ammonium polyphosphate and zinc borate

A novel polyhydroxy triazine-based charring agent, N-tris(hydroxymethyl)-amino triazine-piperazine copolymer (TTPC), was synthesized from piperazine, cyanuric chloride and tris(hydroxymethyl) aminomethane. The chemical structure of TTPC was characterized by Fourier transform infrared spectroscopy and 13C solid-state nuclear magnetic resonance. TTPC, ammonium polyphosphate (APP) and zinc borate (ZB) were then introduced into polypropylene (PP) by melt compounding to improve the fire performance of the composites. The test results showed that the presence of 21% APP-TTPC-ZB with mass ratio of 16:4:1 could significantly reduce the peak heat release rate from 1547 to 230 kW/m2, increase the limiting oxygen index value from 18.0 to 29.6% and upgrade the UL-94 rating from no rating to V-0, accompanied by the elimination of melt dripping. The thermal stability and charring behaviors of the composite samples were investigated by thermogravimetric analysis. The results showed that TTPC was a highly efficient charring agent, and ZB could act as synergist in the intumescent system. Based on the comprehensive study of fire performance, char morphology and mechanical properties, it can be concluded that TTPC is a superior charring agent, especially compared with the generally used pentaerythritol.

ОПТИМІЗАЦІЯ ЕКСПЛУАТАЦІЙНИХ ВЛАСТИВОСТЕЙ ВОГНЕЗАХИСНОГО ПОЛІМЕРНОГО ІНТУМЕСЦЕНТНОГО ПОКРИТТЯ

Study of the effect of intumescent complex compounds on the basis of aminoderivatives of 2,4,8,10-tetraoxа-3,9-diphosphaspiro[5,5] undecane on the flame retardant properties and water resistance of the ethylene vinyl acetate copolymer in the flame retardant polymer compositions. The structure of intumescent compounds has been confirmed by the methods of elemental analysis and IR spectroscopy, the flame retardant properties of the intumescent systems have been investigated using the method of thermogravimetric analysis. Methods of synthesis of intumescent compounds based on 2,4,8,10-tetraoxа-3,9-diphosphaspiro[5,5]undecane and urea, melamine, dicyandiamidе and mixtures there of have been developed. The synthesized compounds have been shown to enhance the flame retardant properties of the ethylene vinyl acetate copolymer, exhibit an intumescent effect and participate in the construction of a char thermal insulation layer. It has been shown that the water resistance of fire retardant systems with the participation of intumescent complex compounds is much higher than the systems of ammonium polyphosphate / melamine / pentaerythritol composition. The expansion coefficient of intumescent systems containing of intumescent compounds to decrease by 10 - 20% after hydrothermal effects, while, as the expansion coefficient of the traditional intumescent system in the same conditions is reduced by 40%. According to the results of accelerated hydrothermal tests, the stability of polymeric intumescent coatings with the participation of intumescent complex compounds to the action of moisture under conditions of temperature difference was determined. The obtained results indicate the prospect of using the investigated intumescent compounds for the creation of new technologies of intumescent coatings for wood with a long operation life.

Preparation of methacrylic acid modified microcrystalline cellulose and their applications in polylactic acid: flame retardancy, mechanical properties, thermal stability and crystallization behavior

Microcrystalline cellulose (MCC) extracted from bamboo powder was used as bio-based carbon source in intumescent system. Before using, MCC was modified with methacrylic acid (MA) by grafting polymerization to prepare MA-MCC, which may improve both the dispersibility and compatibility of in/with polylactic acid (PLA). MA-MCC, together with ammonium polyphosphate, was blended into PLA by melt compounding. The flame retardant properties of the composites were characterized by the limiting oxygen index (LOI), UL-94 vertical burning test and cone calorimeter test. The results showed that the LOI of PLA composite sample containing 3% MA-MCC and 7% APP could reach up to 26.8% and pass V-0 rating in UL-94 test. The addition of APP and MA-MCC could also decrease the peak heat release rate from 556 kW/m2 of neat PLA to 456 kW/m2 and form a continuous, dense, homogeneous residue char to prevent PLA from further burning. Thermogravimetric analysis showed that the presence of APP and MA-MCC could enhance the thermal stability of the composites, which is also essential for the improvement of fire performance. The mechanical properties of PLA composites were also improved with the unnotched impact strength increased to 8.16 kJ/m2 and Young’s modulus increased to 1612.8 MPa. The possible mechanisms for the improvement of flame retardancy and mechanical properties had also been proposed.

Poly(isosorbide carbonate): A ‘green’ char forming agent in polybutylene succinate intumescent formulation

A new flame retardant (FR) intumescent system for polybutylene succinate (PBS) was developed using poly(isosorbide carbonate) (PIC), a bio-based polymer, as a ‘green’ char forming agent. The use of this charring agent in PBS/ammonium polyphosphate (APP) permits to obtain better efficiency than PBS/APP alone for mass loss cone calorimetry (MLC) test: pHRR was decreased by 24% vs 19%, THR was decreased by 48% vs 25% and the yield of residue was increased to 44% vs 23% respectively. According to the temperature measured by thermocouples embedded in the sample, the char formed for PBS/PIC/APP showed a better heat barrier effect than that of PBS/APP: under the char, the temperature and the heating rate of PBS/PIC/APP is significantly lower than those of PBS/APP. Obvious differences of the chemical composition and the morphology of the chars highlight that the good results obtained for PBS/PIC/APP were governed by a glass type char formed during the MLC test.

Investigation of melt spinnability of plasticized polylactic acid biocomposites-containing intumescent flame retardant

Biodegradable polymers from renewable resources have attracted interest due to environmental pollution caused by the disposal of non-degradable polymers, and engineering them to produce fibres of textile grade can improve the environmental sustainability of textile sector. Flame retardancy of polylactic acid (PLA) can be improved if used in intumescent system containing acidic and carbonic source; however, spinning them to produce fibres of textile grade is a big challenge. We therefore have prepared PLA composites containing phosphorous–nitrogen-based flame retardant as acidic source together with kraft lignin as carbonic source. Different quantities of flame retardant and kraft lignin were added to PLA matrix by melt blending and then hot-pressed to form moulding sheets. A modified polyester-based plasticizer was also incorporated to facilitate the spinnability of the composites. Limiting oxygen index values and UL-94 ratings of the composites were reported. The melt spinnability of composites was then assessed, and flame retardancy of knitted structures produced from multifilament yarns was tested by cone calorimetry. Composites containing up to 7% (m/m) of lignin were spinnable together with 10% (m/m) of plasticizer. A substantial decrease of 59% in heat release rate was observed compared to pure PLA. The mechanism of intumescence was also reported.

Sulfenamides in synergistic combination with halogen free flame retardants in polypropylene

Sulfenamide based radical generators that contain a nitrogen-sulfur (N-S) core, can alone provide flame retardancy in polypropylene (PP), polyethylene and polystyrene, as we have earlier demonstrated. Herein, sulfenamides potential as synergists with conventional halogen free flame retardants has been explored. Thus, five different sulfenamides were individually combined with selected eco-friendly, phosphorus based flame retardants or aluminium trihydroxide (ATH), and their effect on polypropylene flammability was assessed by limiting oxygen index (LOI), vertical flammability (UL 94 V) and cone calorimeter tests. Thermogravimetric analysis (TGA) and nuclear magnetic resonance (NMR) studies were carried out to detect changes in thermal behaviour when such two component FR systems were mixed together at different ratios. TGA-FTIR (thermogravimetric analysis-Fourier transform infrared spectroscopy) was used to investigate the differences in decomposition products of non-flame retarded versus flame retarded PP. Strong synergistic effects were observed, and the UL 94 V-0 rating was reached for PP with a total FR loading of 10 wt% using 8 wt% of phosphonate ester AFLAMMIT®PCO 900 together with 2 wt% of sulfenamide flame retardant. In a ternary mixture of an additional phosphazene additive (SPB-100), the needed total concentration for V-0 rating was further reduced to 9 wt%. In addition, the combination of 4 wt% of aluminum hypophosphite (AHP) with 0.5 wt% of sulfenamide offered a unique halogen free solution for achieving UL 94 V-2 rating in PP. Cone calorimeter studies of an ammonium polyphosphate-pentaerythritol based intumescent system in combination with 0.5 wt% of sulfenamide also showed encouraging results. The char stability was enhanced, the peak of heat release rate (HRR), CO and CO2 production and total smoke generation were all reduced compared to the reference sample without sulfenamide.

Definition of the thermal and fire-protective properties of ethylene-vinyl acetate copolymer nanocomposites

To create a fire retardant coating that can be applied in the hydrocarbon fire, the nanocomposites of the ethylene-vinyl acetate (EVA) copolymer with montmorillonite (MMT), thermally expanded graphite (EG) are synthesized and their structure, physicochemical and thermal properties are studied. Using IR spectroscopy and X-ray phase analysis, it is found that the EVA nanocomposites with montmorillonite and nanographite obtained in solution and melt have the same structure. Thermal-oxidative degradation of the EVA copolymer and nanocomposites on its basis in the temperature range of 100–700 °C is investigated. It is proved that nanoclay and nanographite as a part of nanocomposites increase thermal characteristics of the original polymers. The thermal stability of the studied compounds increases in the series: polymer<polymer-EG<polymer-MMT <polymer-MMT-EG. It is shown that the presence of nanoparticles in the polymer matrix reduces the EVA thermal decomposition rate at a temperature above 450 °C and increases the coke residue mass after the destruction of the initial EVA copolymer at a temperature of 250 °C. The synergistic effect of the MMT/EG mixture on the processes of slowing down the thermal degradation of the EVA copolymer is found. The effect of organomodified montmorillonite and graphite in the EVA nanocomposites on the thermal destruction of the intumescent system of ammonium polyphosphate/melamine/pentaerythritol is studied. The synergistic effect of the mixture of clay and graphite nanoparticles in a hybrid nanocomposite is revealed. Synergism consists in increased fire resistance of metal structures by almost 20 % compared with the coating containing the polymer-nanoclay or polymer-nanographite nanocomposite. Based on the results obtained, the intumescent base of fire retardant paint for steel structures, which is recommended for use to increase the fire-resistance rating of metal in the hydrocarbon fire is developed

Investigation of the Flammability and Thermal Stability of Halogen-Free Intumescent System in Biopolymer Composites Containing Biobased Carbonization Agent and Mechanism of Their Char Formation.

Starch, being a polyhydric compound with its natural charring ability, is an ideal candidate to serve as a carbonization agent in an intumescent system. This charring ability of starch, if accompanied by an acidic source, can generate an effective intumescent flame retardant (IFR) system, but the performance of starch-based composites in an IFR system has not been tested in detail. Here, we describe a PLA-based IFR system consisting of ammonium polyphosphate (APP) as acidic source and cornstarch as carbon source. We prepared different formulations by melt compounding followed by molding into sheets by hot pressing. The thermal behavior and surface morphology of the composites was investigated by thermogravimetric analysis and scanning electron microscopy respectively. We also conducted limiting oxygen index (LOI), UL-94, and cone calorimetry tests to characterize the flame-retardant properties. Cone calorimetry revealed a 66% reduction in the peak heat release rate of the IFR composites compared to pure PLA and indicated the development of an intumescent structure by leaving a residual mass of 43% relative to the initial mass of the sample. A mechanism of char formation has also been discussed in detail.

Effect of chicken eggshell on the flame‐retardant and smoke suppression properties of an epoxy‐based traditional APP‐PER‐MEL system

An eco‐friendly bio‐filler was prepared by reusing of chicken eggshell (CES), and well characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM)‐energy dispersive X‐ray spectroscopy (EDS), X‐ray fluorescence spectrometry (XRF), and thermo‐gravimetric (TG) analysis. The influence of CES on the thermal stability, flame‐retardant, and smoke suppression properties of epoxy‐based traditional intumescent system was investigated by limited oxygen index (LOI), UL 94 test, cone calorimeter test, and TG analysis. The results shows that the incorporation of CES improves the LOI value of the samples, and IFR‐3 with 37 wt% intumescent flame retardant (IFR) and 3 wt% CES exhibits the maximum LOI value of 31.5%. The results from cone calorimeter and smoke density tests reveal that the addition of CES greatly decreases the heat release and smoke production of the samples concomitant with an increase in the residual weight, which is ascribed to the formation of a more compact, thermally stable, and intumescent char against heat and mass transfer during burning. The synergistic effect on fire performance between CES and IFR depends on the content of CES, and an excessive content of CES diminishes this synergistic effect. The TG analysis shows that the intumescent system containing CES exhibits high thermal stability and char‐forming ability. Overall, CES can serve as an environmentally friendly bio‐filler and a promising synergist for intumescent systems. POLYM. COMPOS., 40:2712–2723, 2019. © 2018 Society of Plastics Engineers

Benign design and the evaluation of pyrolysis kinetics of polyester resin based intumescent system comprising of alkali-activated silica fume

Novel polyester resin based intumesced flame retardant (IFR) coating was fabricated via a facile sol-gel method, which was modified by the Na2SiO3 alkali-activated silica fume. The emphasis was placed on its flame retardancy and pyrolysis kinetics, it focused on benign design and in-depth research on the flame retarding mechanisms of the inorganic-organic hybrid coating. The results demonstrated that the specimen doped alkali-activated silica fume (2 wt%) exhibited the highest flame retardant efficiency through cone calorimeter (CC) test, evidenced by the peak heat release rate (p-HRR) value of 128 kW m−2 (decreased by 42.1% compared with the sample without silica fume). Pyrolysis kinetics calculated using modified Coats-Redfern integral method determined that the D3 diffusion model governed the pyrolysis process, due to the formation of silicon phosphate and sodium silicate, as well as the continuous protecting layer, leading to an increase in the value of Ea during 112–251 °C. It established that the incorporation of appropriate Na2SiO3 activated silica fume in polyester resin based IFR was conducive to benign design of inorganic-organic hybrid coating.

Evaluation of Mechanical Performance and Flame Retardant Characteristics of Biomass-based EVA Composites using Intumescent Flame Retardant Technology

Intumescent system is a highly effective flame retardant technology that takes advantage of the mechanism of foaming and carbonization. In order to materialize Intumescent system, it is necessary to use reinforcement material to improve the strength of the material. In this study, we used kenaf as a natural fiber to manufacture intumescent/EVA (ethylene vinyl acetate) composites to improve mechanical and flame retardant performance. Finally two materials with different particle shape are applied to one system. Therefore, the influence factors of the particles with different shapes on the composite material were analyzed based on the tensile test. For this purpose, we have used the tensile strength analysis model and confirmed that it can only act as a partial strength reinforcement due to weak binding force between the matrix and particles. In the combustion characteristics analysis using cone calorimeter and UL 94, the combustion characteristics were enhanced as the content of Intuemscent was increased. As the content of kenaf increased, combustion characteristics were strengthened and carbonization characteristics were weakened. Through the application of kenaf, it can be confirmed that elastic modulus improvement and combustion characteristics can be strengthened, which confirmed the possibility of development of environmentally friendly flame retardant materials.

Ball milled bauxite residue as a reinforcing filler in phosphate-based intumescent system

Bauxite residue (BR) is an alumina refinery waste with a global disposal problem. Of the 120 MT generated annually, only 3 MT is disposed via utilization. One of the significant challenges to sustainable utilization has been found to be the cost of processing. In this work, using ball milling, we achieved material modification of bauxite residue. Spectrometric imaging with FESEM showed the transformation from an aggregate structure to nano, platy particulates, leading to particle size homogeneity. BET analysis showed surface area was increased by 23%, while pH was reduced from 10.8 to 9.1 due to collapsing of the hydroxyl surface by the fracturing action of the ball mill. Incorporation of this into a phosphate-based fire retardant, intumescent formulation led to improved material dispersion and the formation of reinforcing heat shielding char nodules. XRD revealed the formation of ceramic metal phosphates which acted as an additional heat sink to the intumescent system, thereby reducing char oxidation and heat transfer to the substrate. Steel substrate temperature from a Bunsen burner test reduced by 33%. Therefore, ball milling can serve as a simple, low-cost processing route for the reuse of bauxite residue in intumescent composites.

난연특성을 가지는 EVA/Intumescent/나노클레이 복합재료 제조 및 교호집성재(Cross Laminated Timber) 적용 기술

최근 들어 늘어나고 있는 도시형 화재 사고와 건축 외장재에 따른 화재 피해 사례의 증가에 따라 난연처리기술의 중요성이 부각되고 있다. 특히, 목재를 기반으로 한 건축재료의 활용에 있어서 난연처리기술은 더욱 중요하게 평가되고 있다. Intumescent 시스템은 비할로겐계 난연처리기술의 하나로, 발포와 탄화층 형성을 통하여 난연성을 구현하는 시스템이다. 본 연구에서는 Intumescent 시스템을 적용하기 위해 Ethylene vinyl acetate (EVA)를 매트릭스로 채용하여 복합재료를 제조하였다. Intumescent 시스템의 난연특성을 강화하기 위해 나노클레이를 함께 적용하였다. Intumescent 시스템과 나노클레이 기술을 함께 적용한 복합재료를 시트상의 시험편으로 가공한 후, 이를 활용하여 표면의 난연특성이 강화된 새로운 구조의 교호집성재를 제작하였다. Intumescent 시스템을 적용한 복합재료의 연소특성 평가에서 최대 열방출량이 효과적으로 감소되는 것을 확인할 수 있었다. 표면에 부착된 구조에 따라 CLT는 두 단계에 걸친 연소 현상이 발생했다. 또한, 심부 연소 과정에서 최대 열방출률이 크게 감소하는 경향을 확인할 수 있었다. 이러한 특성은 목재의 연소과정에 있어 연소 확산지연효과가 있을 것으로 판단된다. 표면단판에 대한 난연처리기술 및 복합재료 적용 최적화 기술을 통해 보다 화재특성이 개선된 CLT 구조체 개발이 가능할 것으로 기대된다. Recently, the importance of flame retardation treatment technology has been emphasized due to the increase in urban fire accidents and fire damage incidents caused by building exterior materials. Particularly, in the utilization of wood-based building materials, the flame retarding treatment technology is more importantly evaluated. An Intumescent system is one of the non-halogen flame retardant treatment technologies and is a system that realizes flame retardancy through foaming and carbonization layer formation. To apply the Intumescent system, composite material was prepared by using Ethylene vinyl acetate (EVA) as a matrix. To enhance the flame retardant properties of the Intumescent system, a nano-clay was applied together. Composite materials with Intumescent system and nano - clay technology were processed into sheet - like test specimens, and then a new structure of cross laminated timber with improved flame retardant properties was fabricated. In the evaluation of combustion characteristics of composite materials using Intumescent system, it was confirmed that the maximum heat emission was reduced efficiently. Depending on the structure attached to the surface, the CLT had two stages of combustion. Also, it was confirmed that the maximum calorific value decreased significantly during the deep burning process. These characteristics are expected to have a delayed combustion diffusion effect in the combustion process of CLT. In order to improve the performance, the flame retardation treatment technique for the surface veneer and the optimization technique of the application of the composite material are required. It is expected that it will be possible to develop a CLT structure with improved fire characteristics.

Effects of the Nanoclay and Intumescent System on the Properties of the Plasticized Polylactic Acid

Effects of the Nanoclay and Intumescent System on the Properties of the Plasticized Polylactic Acid

Effects of the Nanoclay and Intumescent System on the Properties of the Plasticized Polylactic Acid

Effects of the Nanoclay and Intumescent System on the Properties of the Plasticized Polylactic Acid

Environmentally friendly intumescent coatings formulated with vegetable compounds

Abstract Intumescent coatings have been presented as a great choice for the protection of steel structures against fire due to their ability to provide thermal insulation of the metal substrate by the formation of a protective carbonaceous layer. The carbon source is one of the main components of the intumescent system and usually it comes from non-renewable sources. Therefore, the development of more environmentally friendly alternatives is essential. In this work, epoxy resin coatings were prepared with vegetable compounds (ginger powder and coffee husk) to act as a carbon source in the intumescent system. In addition, the possibility of using zinc phosphate (ZnP) and triphenyl phosphate (TPP) as flame retardants has been verified. The characterization of the coatings was performed through a fire resistance test, thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and pyrolysis gas chromatography mass spectrometry (Py-GC–MS). Both vegetable compounds showed potential for application as a carbon source, decreasing the temperature of the substrate when compared to the blank condition. Coatings containing TPP show better behaviour as flame retardants and better expansion than ZnP. Py-GC–MS analysis shows the absence of toxic gases such as CN − and phosphine.

Establishment of the mechanism and fireproof efficiency of wood treated with an impregnating solution and coatings

Description of the behavior of fireproof means and coatings, including those swelling, in the moment of the formation of a thermal insulating structure is a special and complex task. In general, it covers both stages of the process of thermal protection: both heat transfer and subsequent swelling of the coating, which is formed during fire protection. In necessitates studying conditions for the formation of barrier to thermal conductivity and the establishment of a mechanism of fire protection from layer to a layer of coke. Given this, we examined the process of fire protection with work of an impregnating solution and at swelling of a fireproof coating. Data that we obtained revealed that the formation of volatile products under the effect of coating at high temperature occurs with the formation of noncombustible substances. We established experimentally that under the action of heat flow on the fireproof samples, intense release of inert gases occurs, as well as a reduction in the combustible, which leads to the effectiveness of fire protection in reverse order. It was found in the course of conducted tests that the intensity of the formation of noncombustible gases shifts toward elevated temperature with the formation of coked cellular material. Results of determining a swelling capacity of coating for the intumescent system demonstrated that under the influence of high-temperature flow, material combustion and weight loss of the coating is reduced by more than twice due to the formation of high-temperature compounds; in this case, the time to reach a limit temperature grows as well. A coating under the influence of high temperature forms a significant coefficient of swelling, contributes to the formation of a thermal insulating layer of coke, which prevents wood from burning, as well as the passage of high temperature to the material. In general, the efficiency of wood fire protection revealed that the goods belong to the materials that are difficult to combust, which spread the flame over surface slowly and with low smoke-generating capacity. protection means; fire resistance; volatile products; loss of weight; surface treatment; efficiency of protection

Coupled thermo-physical behaviour of an inorganic intumescent system in cone calorimeter testing

This article examines the thermo-physical behaviour of an inorganic-based intumescent coating, tested with bench-scale cone calorimetry, in order to promote the understanding of its intumescence and to contribute to the optimisation of its thermal insulation performance. In the test, the specimen underwent the following phenomena simultaneously: (1) thermo-kinetic endothermic water vaporisation; (2) formation of micro-scale pores in its internal volume; (3) expansion of its volume; (4) variations in thermal boundaries. These simultaneous phenomena cause several changes in internal–external conditions given to the test sample: (1) loss of mass (water molecules); (2) reduction of effective thermal conductivity owing to its porous structure; (3) increase in length of the conductive heat transfer path across its expanding volume; (4) irradiance intensification and additional heat transfer generation on its moving boundaries, exposed to the heat source and surroundings. This interacting thermo-physical behaviour impedes the heat transfer to the underlying substrate. It is therefore comprehensively explained by finite element analysis, associated with the experimental data obtained from a thermogravimetric analyser, differential scanning calorimetry, electric furnace and cone calorimeter tests. The numerical predictions agreed with the physical measurements with consistent accuracy, in terms of both histories of substrate temperature and coating-thickness expansion. This combined numerical–experimental approach enables clear interpretation on the process of intumescence, the impediment mechanism of heat transfer and the critical factors of the material’s behaviour.