Enhancing Flame-Retardant Properties of Polyurethane Composites Using N-β-(Aminoethyl)-γ-aminopropyl Trimethoxysilane and Carbon Black Co-Modified Ammonium Polyphosphate
, Baoluo Xu 1, Kexi Zhang 1, Jianhua Bi 1, Jingxing Wu 1 and Zhong Wang 2Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn the manuscript titled “Enhancing flame-retardant properties of polyurethane composites using N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane and carbon black co-modified ammonium polyphosphate”, the authors have synthesized polyurethane composites by incorporating modified ammonium polyphosphate (APP) and carbon black (CB)-coated APP into the PU matrix and studied the flame retardant properties of the PU composites through thermogravimetric analysis, limiting oxygen index (LOI), and vertical combustion (UL) experiments. The scientific study presented lacks originality because flame retardant polymers composites with APP and CB, similar to that reported in the current study, is already present in the literature. The reviewer recommends the following revisions to the manuscript before it can be accepted for publication. Please refer to the following comments/suggestions:
1. For the clarity of the readers please mention the protocol to prepare the PU composites (APP/PU and CBAPP/PU) in the materials and methods section. Include citations as necessary.
2. In Sec 2.3, although the authors have mentioned the standard procedure adopted for each experiment (LOI, UL, mechanical testing etc.), it will help the new readers if the authors briefly describe the procedures as well for each experiment.
3. The vertical combustion experiment: is there a reason for keeping the width of the sample at 12.8 mm, which is much higher than the standard upper limit of 3 mm?
4. Consider testing the flame-retardant properties of the composites by cone calorimetry test and report key parameters, including the heat release rate (HRR), total heat release (THR), rate of smoke production (SPR), and total smoke production (TSP), etc. in the manuscript.
5. Sec 3.1.4, lines 184 – 188: it might appear unclear to some of the readers how higher residual amount indicates that Si-O-Si network on APP surface and CB slows down the decomposition of APP. Please explain in a little more detail.
6. Fig. 5b and Table 1: what type of degradation corresponds to Tmax3 in APP? Why is it missing in CBAPP?
7. Mention what type of PU has been used in the study (soft segment and hard segment components).
8. Provide the FTIR spectra of the neat PU, identifying the NCO stretching to support the claim that there are free NCO in the PU, which reacts with the free amine functionality in KH792.
9. Also, provide the FTIR spectra of the PU composites (APP/PU and CBAPP/PU).
10. Pg 8, lines 242 – 245: A typical thermal degradation profile (TGA and DTG) for any common PU shows two distinct degradations: one corresponding to the breakage of the urethane groups and the other corresponding to the degradation of the polyol. Please try to correlate the structure of the PU used in the study and the TGA results in the discussion part.
11. Figure 9b: why is the 2nd degradation missing in the polymer composites?
12. Pg 8 lines 269 – 271: Please highlight the interface on the SEM image in Figure 10a.
13. Please mention the self-extinguish time and the total burning time in the UL-94 test.
14. The Figure 11 is almost similar to the Scheme 2 of Ref #22. Please redo this figure.
15. Check for typos (e.g., Pg 8 line 214: Figure 8 will be Figure 9; Pg 10: Figure 10 will be Figure 11; Pg 4: NH4+ will be NH4+, etc.)
Author Response
Please see the attchment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsDear Authors,
In this manuscript, the authors present a method to improve high-performance flame-retardant polymer-based composites, which presents a considerable contribution to fire safety. The manuscript looks good for publication, but there are some minor revisions that should be considered.
-abstract was expressed in scattered form. It should be coherent and show an overall view of the manuscript.
-The introduction should be expanded to help readers follow the manuscript in a coherent pattern. It seems that the manuscript has different, separate parts without any connection between them.
-Section 2 should be improved. It is acceptable that the results of a manuscript can be more important, but other sections that present the manuscript have the same significance.
-Explain how you chose the range of the temperatures. Why?
-Present the conclusion in a way that is more attractive, like using bullet points.
Regard
Comments on the Quality of English Language
There are some English language errors that should be addressed.
Author Response
Please see the attchment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsIn the revised manuscript titled “Enhancing flame-retardant properties of polyurethane composites using N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane and carbon black co-modified ammonium polyphosphate”, the authors have addresses some of the comments/questions and left out some of them. The comments/suggestions were made to enhance the Results and discussion, ensuring that the findings are more understandable to the readers. I feel that the manuscript has not been improved enough and is not suitable for publication in the journal. Additionally:
In the response to reviewer the authors’ response to Comment #13 is: ‘Due to the long testing period, the self-extinguishing time and total burning time in the UL 94 test cannot be provided’. It is unclear what the authors mean by that statement.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 3
Reviewer 1 Report
Comments and Suggestions for AuthorsAlthough the authors have addressed in a separate Response to Reviewer file the comments/suggestions made on the previous versions of the manuscript, they have not included the data in the current version of the manuscript. For the clarity of the readers, the reviewer strongly recommends that the authors consider doing that.
Author Response
Thank you for your suggestion. We present these data in the supplementary material.
