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Article

Fire Risk of Polyethylene (PE)-Based Foam Blocks Used as Interior Building Materials and Fire Suppression through a Simple Surface Coating: Analysis of Vulnerability, Propagation, and Flame Retardancy

by
Yongtae Jeon
1,
Jungwoo Park
2,
Jongyoung Park
2 and
Chankyu Kang
3,*
1
Fire Technology Research Division, National Fire Research Institute of Korea, Asan-si 31555, Republic of Korea
2
Division of Fire Safety Laboratory, National Fire Research Institute of Korea, Asan-si 31555, Republic of Korea
3
School of Social Safety System Engineering, Research Center for Safety and Health, Hankyong National University, Anseong-si 17579, Republic of Korea
*
Author to whom correspondence should be addressed.
Fire 2023, 6(9), 350; https://doi.org/10.3390/fire6090350
Submission received: 25 June 2023 / Revised: 20 July 2023 / Accepted: 6 September 2023 / Published: 8 September 2023
(This article belongs to the Special Issue Compartment Fire and Safety)
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Abstract

:
Building fires can spread through surface combustion of both combustible and interior finishing materials. Recently, the use of foam blocks as interior materials for high-rise residential buildings has increased. However, as foam blocks are primarily composed of polyethylene, they are not flame-retardant and can readily burn and the fire can spread, leading to large-scale damage. Herein, the fire hazard and diffusion characteristics of foam blocks were compared with those of flame-retardant and general wallpapers to confirm the risk of fire. The fire risk of the foam blocks was confirmed using flammability, cone calorimetry, and spread-of-flame analyses. Based on a comparative analysis of the fire risk of foam blocks, the average total heat release was 11.2 MJ/m. This is approximately three times higher than the average heat release rate of the flame-retardant wallpaper and approximately two times higher than that of the general wallpaper. The foam blocks ignited rapidly owing to fire and generated large amounts of combustion gas and heat. To prevent such a fire, 5 wt% montmorillonite (MMT) was simply coated after surface modification to suppress the occurrence of fire. Various flame-retardant materials, surface modifications, and fire safety systems must be developed to prevent fire hazards.

1. Introduction

Various interior materials, such as natural, synthetic, and mixtures of organic/inorganic materials, are used to achieve high-quality interior finishing [1,2]. Although these materials have many advantages such as aesthetics and durability, most contain combustible substances [3]. In addition, a small spark or radiant heat can readily ignite these materials, causing a wide-spread fire by combustion [4]. The most common finishing materials for interiors in residential buildings are paint and wallpaper [5]. According to individual preference, interior wallpapers with various colors and textures can be readily and rapidly applied on walls and ceilings that occupy maximum space in buildings. Recently, the convenience of construction and the advantages of low cost have expanded the usability of wallpapers to various spaces, including hotels and commercial spaces, and the types of wallpapers have also diversified according to purpose [6,7].
Paper-based duplex wallpaper, which is the most widely used wallpaper, has the advantages of being eco-friendly, self-applicable, and resistant to mechanical damage [8]. Recently, natural wallpapers have been used to inhibit the emission of endocrine disruptors, purify indoor air, and exert antibacterial effects [9]. Because these wallpapers are vulnerable to fire, fire-retardant wallpapers with various surface coatings are used to overcome these disadvantages [10,11]. As a specialized type of wallpaper with flame-retardant properties, it is mainly used in public spaces, including commercial buildings, because it can mitigate the damage caused by fire by reducing the spread of flame [12]. Polyethylene (PE)-based foam insulation wallpaper is an economical and customizable interior decoration material that is widely used. A foam block composed of a highly flammable PE-based synthetic resin without additional flame-retardant treatment may spread the fire during a fire outbreak [13,14].
Wallpapers are classified as household products that are widely used in interior decoration. Their manufacture and use are regulated according to appropriate safety and labeling standards under the Electrical Appliances and Household Products Safety Management Act in South Korea. Owing to the possibility of accidents or health hazards during handling, use, and transportation by consumers, manufacturers or importers must ensure product safety by testing it either directly or indirectly through certification agencies [15]. Therefore, the use of PE-based foam wallpaper without flame retardancy in public facilities is restricted according to legal regulations owing to toxic gas emissions [16]. However, as the aforementioned laws do not apply to general households in South Korea, PE-based foam wallpapers can be readily purchased at low costs from large markets and online stores, thereby increasing vulnerability to fire.
Fire-retardant coatings can protect both combustible and non-combustible products from fire; they represent the oldest, most efficient, and easiest way to easily apply fire protection to a surface without altering the material’s inherent properties [17]. Particularly in the early stages of a fire, it is important to focus on protecting the surface of the material as ignition occurs at the surface [18]. Flame-retardant coatings, which burn easily due to the organic nature of existing surface coatings and do not generate smoke and toxic gases, are suitable for applications requiring fire protection or fire prevention [19]. To evaluate combustible and non-combustible materials using flame-retardant and fire-resistant coatings, response to fire and/or fire resistance should be considered. It is known that the factors affecting flame retardancy include coating thickness, density, substrates, composite, panel type, and efficiency of formulations [20]. However, the most fundamental factor determining the success or failure of a coating is surface treatment, which is very important as it ensures proper adhesion of the coating to the substrate [21]. Polyhedral oligomeric silsesquioxane (POSS), carbon nanotubes (CNTs), montmorillonite (MMT), graphene nanosheets, and graphitic carbon nitride are known to impart excellent flame retardancy to polymeric materials [22]. Among them, montmorillonite (MMT) is a clay-based natural inorganic material and is a layered aluminosilicate [23]. Recently, montmorillonite clay (MMT) has been widely used to increase flame retardancy by preparing polyurethane (PU) nanocomposites [24].
Recently, the use of PE-based foam block as an interior material in high-rise buildings is rapidly increasing, but there is no research related to fire in indoor buildings in relation to the material. The sales rate of foam block wallpaper is 4.7 times greater compared to that of the same period last year in 2016 and increased by up to 80% compared to the previous year in 2023 [25,26]. Although the use of PE-based foam blocks for public buildings is prohibited in South Korea, there are no legal restrictions on their use in residential areas used by individuals. The objectives of this study were to first characterize the flame-retardant properties of foam blocks, which are currently readily available and easier to use than general wallpaper, and their ability to spread fire through combustion. The fire risk of the foam block was analyzed based on the combustion characteristics using a 45-degreeflammability tester, heat release rate (HRR) using cone calorimetry, and toxic gas analysis using FT-IR spectroscopy. The fire risk of PE-based foam insulation wallpapers was compared and evaluated against flame-retardant and general paper-based wallpapers, which are commercially available and used as materials for interior decoration. In addition, montmorillonite (MMT) was coated on the PE surface through layer-by-layer (LBL) deposition, also known as the thin film fabrication technique, to confirm the flame-retardant performance [27]. This attempt is meaningful in that the flame-retardant effect is obtained by applying MMT to the PE foam block for the first time. Through these analysis results, it is necessary to enact new fire safety regulations for PE-based foam blocks that are vulnerable to fire, while at the same time developing simple and flame-retardant alternatives and securing a safety system.

2. Materials and Methods

To prevent and mitigate fires, interior decoration materials with non-combustible, semi-non-combustible, or fire-retardant properties should be installed, and they should meet the established standards for flame-retardant products. Accordingly, flame retardancy, HRR, spread of flame, and flammability were measured for four types of wallpapers: PE-based foam block, PE-based foam block coated with MMT, flame-retardant, and general paper-based wallpapers.

2.1. Flame Retardancy

The 45-degree flammability test (Korea Fire Assessment Tester Equipment, Ltd., Incheon, Republic of Korea), as shown in Supplementary Figure S1, was performed according to ASTM E662, which is a test method for evaluating the flame retardancy of the sample wallpapers. It is a method for measuring the degree of combustion diffusion on the sample surface and is known to be suitable for thick products [28]. The reason why it is called a 45-degree flammability tester is that the sample is put on a cradle tilted at a 45-degree angle and burned by heating liquefied petroleum gas with an automatic ignition device. The flame retardancy was determined by measuring the heating, after-flame, and residual times due to tangential combustion using a flame at the bottom-center of the sample (250 mm × 350 mm). The samples used in the 45° flammability test are shown in Figure 1. The general wallpaper used in the experiment was purchased from Jeil Wallpaper (Seoul, South Korea) as a paper wallpaper. In addition, the flame-retardant wallpaper was purchased from Seoul Wallpaper (Seoul, South Korea), which has flame-retardant performance implemented in the whole wallpaper. As shown in Figure 1a–c, these samples were not subjected to surface coating to obtain flame retardancy. Meanwhile, a 45° flammability test was performed in the same manner as the non-flame-retardant samples to compare flame retardancy performance after MMT was laminated on the surface of the PE foam block, and the result is shown in Figure 1d. To ensure reliability, the experiment was repeated thrice.
The flame length was set to 24 mm as the distance between the burn exit and the axis point of the stoichiometric line, and each prepared sample was heated for 30 s to determine its suitability as the test standard. The PE-based foam insulation and general wallpapers were highly flammable, making it difficult to measure performance criteria such as after-flame and residual-dust times as well as carbonized area. Table 1 presents the criteria for determining flame retardancy of the samples. Wallpaper is classified as a thin fabric that must adhere to the following conditions: (i) after-flame time within 3 s, (ii) afterglow time within 5 s, (iii) carbonization length within 10 cm, (iv) carbonization area within 30 cm, and (v) material adhesion occurs after the flame is in contact for more than 3 s.

2.2. Heat Release Rate

This parameter was measured according to ISO 5660-1, which is a standard test method for evaluating flame retardancy [29]. The HRR during combustion was determined using a cone calorimeter (FESTEC International Co., Seoul, South Korea). The cone calorimeter is the most widely used instrument for studying the fire safety behavior of materials with relatively small sample sizes [30]. The surface of the sample was heated using a conical heater at 50 kW/m to determine the amount of heat generated during combustion. If this value exceeded 8 MJ/m, the sample was not flame retardant [31]. The experiments were performed at least three times for each wallpaper type to ensure the reliability of the results. Because the cone calorimetry method heats only the surface of the sample, aluminum foil was used to exclude the exposed surfaces, such as the sides of the cut sample.

2.3. Spread of Flame Test

This test was performed according to ISO 5658, which is an international standard test method, and the combustion heat and continuity were confirmed [32,33]. The samples used in the experiment (800 mm width × 155 mm length) were installed at an angle to the radiant panel, and the test was conducted for different incident radiant heat values (1.5–55 kW/m2) based on the location of the samples. Accordingly, the flame ignition time, extinguishing time, and flame propagation speed were determined.

2.4. Flame-Retardant Surface Coating

MMT powder (Kunimine Industries Co., Ltd., Tokyo, Japan) was dispersed in DI water to make a 5 wt% MMT solution. Since lumps are formed by aggregating the MMT powder in the aqueous phase, an ultrasonic instrument (Branson, Brookfield, WI, USA) is used and operated when all lumps disappear. The 5 wt% MMT solution prepared in this way can be applied sequentially on the surface of the PE form block in the LBL method. However, for smooth application of the PE form block, surface modification was first performed using air plasma (Femto Science Co., Ltd., Haesung, South Korea). Surface modification was carried out by exposing it to plasma three times for 15 s with a power of 100 W. A Baker film applicator (TQC sheen Korea, Kimpo, South Korea) was used to uniformly apply MMT to the surface of the PE form block. It proceeded to form a thickness of 250 μm at one time. The additional surface thickness was verified using a digital thickness indicator (Mitutoyo Co., Ltd., Kawasaki, Japan). The flame retardancy performance of the case where MMT was applied to the PE surface 3 times or 6 times and, when MMT was not applied, was compared through a 45° combustion test. After applying MMT to the PE surface, it was placed in an oven (Jeiotech, Daejeon, South Korea) at 60 °C for 5 min. After drying the material in an oven, TGA (RIGAKU, Tokyo, Japan) was run to confirm that water was removed. A brief flame-retardant coating process is shown in Figure 2.

3. Results and Discussion

3.1. Flame-Retardant Properties

As previously mentioned, the after-flame time, afterglow time, and carbonized area of the foam block and general paper-based wallpaper could not be measured owing to their high flammability. In contrast, the flame-retardant wallpaper did not generate a residual flame. For this wallpaper type, the average measured carbonized area was 28.1 cm2, which was within 30 cm2 of the flame-retardancy standard; moreover, the average carbonized length was 7.0 cm, which was within 20 cm of the performance standard. These results indicate that commercially available foam blocks are vulnerable to fire, and can cause large-scale damage to humans and properties owing to their increased use in high-rise residential buildings. The detailed experimental results are listed in Table 2.

3.2. Comparison of Heat Release Rate

Figure 3 shows the temporal changes observed in the flame for the cone calorimeter test on the foam block, flame-retardant wallpaper, and general wallpaper. The flame was ignited simultaneously and similarly at the start of the test for all three types of samples. The flame of the foam block increased for 25 s after ignition, then gradually decreased, and was extinguished within an average of 170 s. However, in the flame-retardant wallpaper, the flame was extinguished within an average of 25 s, exhibiting the same phenomenon of increasing and decreasing flames after ignition. Furthermore, the flame of the general wallpaper was extinguished an average of 15 s after ignition. These results showed that the burning time was slightly longer than that of general wallpaper because flame-retardant wallpaper was developed to facilitate fire suppression by delaying the burning time in the event of a fire.
Figure 4 presents the shapes of the samples after the cone calorimeter test. All three sample types were completely burned; in particular, the fire in the foam block was completely extinguished, without generating ash. The foam block was ignited in 4 s, and it burned for approximately 300 s. In contrast, the flame-retardant wallpaper ignited in 72 s and burned only 1/5 of the sample area, whereas the general wallpaper ignited in 50 s and burned only 1/2 of the area.
Table 3 shows the total heat release (THR) analyzed using the cone calorimeter test for the foam block, flame-retardant wallpaper, and general wallpaper. After ignition, different fire properties were observed depending on the material. The foam block exhibited THR values of 10.4–11.9 MJ/m for 5 min all three times, with an average of 11.2 MJ/m, which exceeded the flame retardancy standard of 8 MJ/m. In contrast, the THR of the flame-retardant wallpaper was 3.2–3.4 MJ/m, and that of the general wallpaper was 4.9–5.2 MJ/m, both of which met the flame retardancy standard. Compared with the flame-retardant wallpaper, the general wallpaper exhibited weak flame retardancy. Therefore, the heat from the general wallpaper increased rapidly at the beginning and remained constant after burning, whereas the heat from the flame-retardant wallpaper gradually increased as the ignition and extinction of the flame were delayed.
The HRR in terms of the instantaneous heat release according to the changes in the flame for each sample is shown in Figure 5. Among the three types of samples, the foam block released the highest heat of 174 kW/m, approximately 25 s after the start of the test. The instantaneous HRR of the general wallpaper was the second highest with a maximum of 65 kW/m within approximately 20 s, and that of the flame-retardant wallpaper was the lowest with a maximum of 54 kW/m within approximately 25 s.

3.3. Spread of Flame Test

Table 4 presents the measured flame ignition time, extinguishing time, flame propagation speed, and average heat for sustained combustion or burning (Qsb) to confirm the ability of the material to propagate the flame after ignition. The critical flux at extinction (CFE) is the amount of heat received per unit area per hour at the point where the flame does not propagate further during the combustion of the sample. Generally, a lower CFE value corresponds to a higher fire hazard [34]. For the foam block, the analyzed CFE value was the lowest among the three samples with an average of 0.8 kW/m, and the Qsb value was the lowest with an average of 0.28–0.35 MJ/m. The Qsb is defined as the value multiplied by the flame propagation time and divided by the distance. The lower the Qsb value, the shorter the flame propagation time, indicating better combustion. These results indicate the high vulnerability of the foam blocks to fire. In contrast, the flame-retardant wallpaper exhibited the highest CFE of 42.81–49.59 MJ/m, and the average Qsb exceeded the measurable limit.

3.4. Flame-Retardant Performance of MMT

The MMT coating was laminated on the PE surface by a simple LBL technique. After drying the MMT in an oven, TGA was performed to confirm that water was removed. As a result, it was confirmed in Supplementary Figure S2 that the water loss was initially about 7~8%, but it was maintained constant thereafter. Through Figure 6, the increase in thickness can be felt with the naked eye, and when performed about three times, the color was slightly changed to yellow. When the MMT coating was repeated seven times, it was confirmed that the surface thickness increased using the digital thickness instrument. This means that MMT was well deposited on the PE surface. The flame retardancy performance of MMT was measured using the 45° combustion tester for the items in Table 1. As a result of the measurement, the performance of MMT was found to be very good in flame retardancy. Ignition itself did not occur in the PE foam block coated with MMT, so the carbonized area and carbonized length could not be obtained. Figure 7 shows the results of an ignition experiment using the 45° combustion tester. Figure 7a was not ignited, so Figure 7b was not ignited even though the heat was applied for about 1 min, confirming the flame retardancy. The flame retardancy performance was better when it was coated six times (i.e., thickness: 1500 μm) than when it was coated three times (i.e., thickness: 750 μm). However, it is judged that the optimal MMT thickness requires additional research in the future.

4. Conclusions

In this study, the fire-safety performance of three types of wallpaper (i.e., PE-based foam block, flame-retardant wallpaper, and general wallpaper) used as interior products was compared to confirm the fire risk of foam blocks that have recently been used in high-rise residential building interiors. Detailed analyses were performed for flame retardancy, HRR, and spread-of-flame tests. All tests were conducted according to international standards. The results of the 45° flammability test confirmed the flame-retardant properties of the flame-retardant wallpaper, whereas the foam block had no flame retardancy; thus, the flame was readily ignited during an actual fire outbreak. The average HRR during the combustion of the foam block using a cone calorimeter was 11.2 MJ/m for 5 min. This value was 2–3 times higher than the average HRRs of the flame-retardant wallpaper (3.3 MJ/m) and general wallpaper (5.0 MJ/m). This implies that the size of a fire occurring in a foam block can be large and its burning rate can be high. The spread-of-flame test revealed that the propagation of the flame generated by the foam block was extremely high, which confirmed that ignition may occur with a small amount of heat and the material can combust easily.
The fire hazard analysis results confirmed the fire hazards of using foam blocks. The increased use of foam blocks as interior insulation materials in high-rise residential buildings can be the main cause of fire propagation because they can spread the fire rapidly during an actual fire event. In South Korea, where a large proportion of the population resides in high-rise buildings, PE-based foam materials can act as major obstacles to evacuation. Therefore, MMT was simply laminated on the surface of the PE foam block using the LBL technique to reduce the risk of fire. As a result of the lamination, it was confirmed that the flame retardancy of the MMT was secured through repeated lamination about three times. In addition, the PE foam block, which was repeatedly laminated about six times, did not ignite even in the heat of 1 min, showing very excellent flame-retardant performance. However, additional research is needed on the optimal thickness required when coating MMT on PE surfaces. Therefore, it is necessary to develop various eco-friendly functional materials with flame-retardant properties in addition to MMT. In addition, it is necessary to introduce a fire safety system to existing foam block-based buildings for rapid evacuation during fire outbreaks.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/fire6090350/s1, Figure S1: 45°-flammability combustion tester image; Figure S2: TGA analysis results for moisture analysis.

Author Contributions

Conceptualization, Y.J. and C.K.; methodology, J.P. (Jongyoung Park); validation, J.P. (Jungwoo Park) and C.K.; formal analysis, Y.J. and J.P. (Jungwoo Park); data curation, J.P. (Jongyoung Park); writing—original draft preparation, Y.J.; writing—review and editing, C.K.; supervision, C.K.; project administration, C.K.; funding acquisition, C.K. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIT), grant number 2021R1F1A1059957.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Conflicts of Interest

The authors declare no conflict of interest.

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Fire 06 00350 g001
Figure 1. Samples for the 45° flammability test: (a) PE foam block without MMT surface coating, (b) flame-retardant wallpaper, (c) general wallpaper, and (d) PE foam block with MMT surface coating.
Figure 1. Samples for the 45° flammability test: (a) PE foam block without MMT surface coating, (b) flame-retardant wallpaper, (c) general wallpaper, and (d) PE foam block with MMT surface coating.
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Figure 2. Flame-retardant coating process.
Figure 2. Flame-retardant coating process.
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Figure 3. Temporal changes during the cone calorimeter test.
Figure 3. Temporal changes during the cone calorimeter test.
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Figure 4. Shapes of the samples remaining after the cone calorimeter test: (a) foam block, (b) flame-retardant wallpaper, and (c) general wallpaper.
Figure 4. Shapes of the samples remaining after the cone calorimeter test: (a) foam block, (b) flame-retardant wallpaper, and (c) general wallpaper.
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Figure 5. Heat release rate (HRR) analysis results for the three wallpaper samples.
Figure 5. Heat release rate (HRR) analysis results for the three wallpaper samples.
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Figure 6. MMT coating using LBL on the PE form block surface. (a) Without MMT coating, (b) three-time coating of MMT, and (c) six-time coating of MMT.
Figure 6. MMT coating using LBL on the PE form block surface. (a) Without MMT coating, (b) three-time coating of MMT, and (c) six-time coating of MMT.
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Figure 7. A 45° combustion test on PE foam block coated with MMT. (a) Three-time coating of MMT and (b) six-time coating of MMT.
Figure 7. A 45° combustion test on PE foam block coated with MMT. (a) Three-time coating of MMT and (b) six-time coating of MMT.
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Table 1. Performance criteria for the 45° flammability test.
Table 1. Performance criteria for the 45° flammability test.
Types of MaterialsAfter-Flame TimeAfter-Glow TimeStandards Carbonization AreasCarbonization LengthFlame Contact Time
CarpetWithin 20 s--10 cm-
Thin fabricWithin 3 sWithin 5 sWithin 30 cmWithin 20 cm>3 s
Thick fabric5 s20 s40 cm20 cm3 s
Synthetic resin plate5 s20 s40 cm20 cm-
Plywood, fiberboard, wood, etc.10 s30 s50 cm20 cm-
Table 2. Comparison of flame retardancy of the three wallpaper types.
Table 2. Comparison of flame retardancy of the three wallpaper types.
Test Sample (No)After-Flame TimeAfterglow TimeCarbonization Area (cm2)Carbonization Length (cm)Flame Contact TimeFlame Retardancy
Insulated wallpaper (foam block)1Burned downBurned downBurned downBurned downBurned downOrdinary (combustibles)
2
3
Flame-retardant wallpaper10.00.027.86.9Not applicableFlame-retardant material
20.00.028.57.2
30.00.028.17.0
General wallpaper1Burned downBurned downBurned downBurned downBurned downOrdinary (combustibles)
2
3
Table 3. Analysis of the total heat release (THR) rate from the test samples.
Table 3. Analysis of the total heat release (THR) rate from the test samples.
Test Sample (No)Ignition (s)Flame Extinction Time (s)THR
(MJ/m2)		Mass Loss Rate (%)Fire
Class
in 5 min
Insulated wallpaper (foam block)1Immediately16511.9≥95Ordinary (combustibles)
2Immediately16510.4
3Immediately18011.3
Flame-retardant wallpaper1Immediately203.2.≥95Flame-retardant material
2Immediately243.4
3Immediately233.3
General wallpaper1Immediately165.0≥95 Ordinary (combustibles)
2Immediately164.9
3Immediately165.2
Table 4. Analysis of flame propagation properties of the test samples.
Table 4. Analysis of flame propagation properties of the test samples.
Test Sample (No)Carbonization Length (mm)Critical Flux at Extinguishment (CFE)
(kW/m2)		Heat for Sustained Burning (Qsb)
(MJ/m2)		Test Time
(s)
Insulated wallpaper (foam block)148000.80.28
248000.80.29
348000.80.35
Average48000.80.3
Flame-retardant wallpaper16920042.81-
27215047.47-
3610049.59-
Average4915047-
General wallpaper15340018.32.55
25135023.72.58
34835023.72.46
Average51367222.5
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MDPI and ACS Style

Jeon, Y.; Park, J.; Park, J.; Kang, C. Fire Risk of Polyethylene (PE)-Based Foam Blocks Used as Interior Building Materials and Fire Suppression through a Simple Surface Coating: Analysis of Vulnerability, Propagation, and Flame Retardancy. Fire 2023, 6, 350. https://doi.org/10.3390/fire6090350

AMA Style

Jeon Y, Park J, Park J, Kang C. Fire Risk of Polyethylene (PE)-Based Foam Blocks Used as Interior Building Materials and Fire Suppression through a Simple Surface Coating: Analysis of Vulnerability, Propagation, and Flame Retardancy. Fire. 2023; 6(9):350. https://doi.org/10.3390/fire6090350

Chicago/Turabian Style

Jeon, Yongtae, Jungwoo Park, Jongyoung Park, and Chankyu Kang. 2023. "Fire Risk of Polyethylene (PE)-Based Foam Blocks Used as Interior Building Materials and Fire Suppression through a Simple Surface Coating: Analysis of Vulnerability, Propagation, and Flame Retardancy" Fire 6, no. 9: 350. https://doi.org/10.3390/fire6090350

APA Style

Jeon, Y., Park, J., Park, J., & Kang, C. (2023). Fire Risk of Polyethylene (PE)-Based Foam Blocks Used as Interior Building Materials and Fire Suppression through a Simple Surface Coating: Analysis of Vulnerability, Propagation, and Flame Retardancy. Fire, 6(9), 350. https://doi.org/10.3390/fire6090350

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