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

Round 1

Reviewer 1 Report

1) Abstract: line 25 ""...such a fire, 5wt% monmolite was simply coated after surface modification.."

I think you mean montmorillonite, instead of "monmolite".

2) Introduction: Line 88-91. You mention foam blocks are more widely available than conventional wallpaper. What is the percentage? Please insert some data to support your statement. In addition, include the percentage of residential areas that are using foam blocks to emphasize the importance of your study.

3) Have you checked the water content in the material? It may be useful to run a TGA to confirm if the water has been eliminated after drying the material in the oven.

Author Response

Response of Reviewer 1 Q1) Abstract: line 25 ""...such a fire, 5wt% monmolite was simply coated after surface modification.." I think you mean montmorillonite, instead of "monmolite". Response) It was our mistake. We modified it (Line 25). Q2) Introduction: Line 88-91. You mention foam blocks are more widely available than conventional wallpaper. i) What is the percentage? Please insert some data to support your statement. ii)In addition, include the percentage of residential areas that are using foam blocks to emphasize the importance of your study. Response) i) We added the corresponding content according to the comment of the reviewer (Line 86). ii) We agree with the reviewer's opinion. Although a government-level survey on the number of households using foam blocks has not been conducted, it can be seen that the number of households using foam blocks is increasing as the sales rate increases. A sales rate was added to the manuscript according to the reviewer's opinion (Line 86). Q3) Have you checked the water content in the material? It may be useful to run a TGA to confirm if the water has been eliminated after drying the material in the oven. Response) We agree with the reviewer’s comment. We initially tried to check the thermal properties through TGA after removing water by putting the sample in an oven. Due to the thickness of the PE form block during the TGA sample preparation process, the coated part was damaged during the sample cutting process. In addition, PE-based form block melted in high heat and affected the electronic balance of TGA, resulting in a technical problem of failure. Therefore, the flame retardancy performance was evaluated using the 45- degree flammability test suitable for samples with some thickness instead of TGA.

Reviewer 2 Report

This work presents some experimental results on the fire risk and retardancy analysis of polyethylene-based foam blocks modified by montmorillonite coatings. The subject can be appealing to the fire safety engineering community and to the readership of Fire. However, before the paper is accepted, substantial action is recommended to improve the contents, which may require additional analysis.

1. English should be improved or checked by a native speaker. There are some opaque expressions, such as “ the flame length of the burner”.

2. The 45℃ combustion test method was used to test the flame retardancy during experiments. It is better to add more information about the method in Section 2. Why is this called 45℃-combustion test? What does the 45℃ refer to?

4. Generally, three types of materials were used in experiments: pure PE-foam blocks, blocks modified by MMT, and generally wallpapers. However, it is unclear what types of general wallpapers are, the physical properties of which could be important when these materials are compared with each other. Can you add some descriptions about this?

5. There is no need to use Fig.2.

6. Fig.4 shows that the burning time of flame-retardant wallpapers is slightly longer than that of general wallpapers. Can you add some explanations for this?

7. Why were the general wallpapers regarded as combustible materials in Table 2 but also as Fire-retardant materials in Table 3?

8. There are misarrangements in Table 4. The experimental number seems to be misplaced under the “ignition time” column.

9. what is the best thickness of MMT?

In overall, the manuscript is understandable, a few grammatical mistakes and awkward sentences still exist. 

Author Response

Response of Reviewer 2

This work presents some experimental results on the fire risk and retardancy analysis of polyethylene-based foam blocks modified by montmorillonite coatings. The subject can be appealing to the fire safety engineering community and to the readership of Fire. However, before the paper is accepted, substantial action is recommended to improve the contents, which may require additional analysis.

Q1) English should be improved or checked by a native speaker. There are some opaque expressions, such as “ the flame length of the burner”.

Response) English proofreading (editage.com: INQ_HANT_913) was performed by a professional company according to the opinion of the reviewer.

Q2) i) The 45℃ combustion test method was used to test the flame retardancy during experiments. It is better to add more information about the method in Section 2. ii) Why is this called 45℃-combustion test? iii) What does the 45℃ refer to?

Response) i) Additional information was added to section 2.1 (Flame retardancy) based on the reviewer's comments (Line 112).  ii) The reason why it is called a 45-degree flammability tester is that the sample is put on a cradle tilted at 45-degree angle and burned by heating liquefied petroleum gas with an automatic ignition device. iii) Ignition and extinguishing time can be set arbitrarily, and 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).

Q3) Generally, three types of materials were used in experiments: pure PE-foam blocks, blocks modified by MMT, and generally wallpapers. However, it is unclear what types of general wallpapers are, the physical properties of which could be important when these materials are compared with each other. Can you add some descriptions about this?

Response) Thanks for the reviewer's comments. Detailed information was added to the manuscript (Line 120-123).

Q4) There is no need to use Fig.2 (Line 158).

Response) We deleted Figure 2 according to the reviewer's comment.

Q5) Fig.4 shows that the burning time of flame-retardant wallpapers is slightly longer than that of general wallpapers. Can you add some explanations for this?

Response) The flame-retardant wallpaper in Figure 4 was developed to facilitate fire suppression by delaying the combustion time in the case of fire. Therefore, the burning time was slightly longer than that of the general wallpaper. However, it is judged that the performance of the fire-retardant wallpaper used in the experiment is not good.

Q6) Why were the general wallpapers regarded as combustible materials in Table 2 but also as Fire-retardant materials in Table 3?

Response) We modified our mistake (Line 234). General wallpaper is made of paper, so it has no flame retardancy and is mainly used for interior decoration.

Q7) There are misarrangements in Table 4. The experimental number seems to be misplaced under the “ignition time” column.

Response) It was our mistake. We modified our mistake (Line 260).

Q8) what is the best thickness of MMT?

Response) The reviewer's question requires additional research, and it was left as a manuscript as a research limitation. The flame retardancy performance was better when it was coated 6 times (i.e., thickness: 1,500μm) than when it was coated 3 times (i.e., thickness: 750μm). However, it is judged that the optimal MMT thickness requires additional research in the future.