Exploring the Thermophysical Properties of the Thermal Conductivity of Pigmented Polymer Matrix Composites with Barium Titanate: A Comparative Numerical and Experimental Study
, Youssef Halimi 1,4 and Mohamed Tahiri 4
Round 1
Reviewer 1 Report
This paper use finite element analysis to evaluate the conductivity of composite material and compare the results with experimental results by taking as an example of BaTiO3/PSU composites. The experimental design process of the paper is reasonable and the results are correct. The language of the paper is relatively fluent, and I believe it can be accepted in the current format.
The English Language is good.
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Reviewer 2 Report
In this work, the authors investigate the thermal behavior of polymer matrix composite materials, specifically those composed of PSU and BaTiO3, both experimentally and numerically. The research appears to be efficiently done and appropriately reported; however, the standard of English must be improved. Nevertheless, there are some questions and corrections that must be answered to improve and complete the document.
Introduction section: In this section, the authors don’t indicate the novelty of their work. what is the innovation of your work when compared with the other researchers? The "Knowledge gap to be filled"? In this introduction, the authors must describe or indicate the work that will be done to test their "hypothesis". In another hand, the number of references is insufficient despite the most of them are updated. So, the introduction must be rewritten based on more research work
The description of the experimental treatment is confusing and without any framework or explanation of what they are doing. For example, what are the authors describing in the "sample preparation"? Are you describing how you made the BaTiO3 particles? How do you mix the particles of BaTiO3 with the PSU? The authors refer that the filler percentage is in volume (ex. Figure 6), however, how do they determine the volume of particles that have such a small size? How is thermal conductivity measured in experimental tests?
Line 163. Are the authors sure of these values? 0.3 and 0.8 m, which corresponds to 300 and 800 mm. Wouldn't the radius values be too high?
Equation 1. What does each of the parameters in the equation mean?
Line 199. The authors wrote, “x and y represent the exchange surface”. I don’t understand, for me a surface is an area, not two directions.
Line 218. Please, verify the figure number.
Line 303. Please, verify the figure number.
Lines 308-310. The authors wrote “significant. The impact of the contact between the matrix and the fillers may be to blame for this variation in thermal conductivity. (the larger the particle size, the more imperfect the matrix inclusion contact).”. Are you sure about this explanation? I think that is not a very good explanation, indeed, for the same percentage of fillers, if the dimension of each one is smaller the contact area of all fillers is higher because much more fillers.
Moderate editing of English language.
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Reviewer 3 Report
Recommendation: Reconsider after major revision
The manuscript “Exploring the Thermophysical Properties of Pigmented Polymer Matrix Composites with Barium Titanate: A Comparative 3 Numerical and Experimental Study” discussed how the thermal conductivity of a polysulfone composite was influenced by the inclusion of BaTiO3 particles. A unique experimental set up was utilized to measure the thermal conductivity. The experimental data was compared with various thermal models and a numerical calculation to validate the results. Overall, a relationship between particle size/concentration and composite thermal conductivity was established. A thermal distribution map of such composite was also developed by numerical calculation.
Major comments:
1. The dimension is 2m for the composite for simulation; does it make sense? That is huge. (line163) Similarly, the authors mentioned that the particle size is 0.2m, but later in the manuscript (line213) the particle size is in µm scale. I am very confused as I read through it. The authors should specify what methods are being used and also re-organize the results/discussion section to avoid confusion.
2. In Figure 5, the labeling is very confusing. The authors mentioned location as “X” but previously in Figure 4 they said the location was “Y”. Figure 5 also uses cell size as “L” in the caption, but I could not find L in the actual figure. The inset of figure uses small “x” and the horizontal axis uses length “Y”. To be fair, the authors must spend more effort into correcting such issues. I could not follow their discussion with such inconsistent data representation.
3. How was Keff determinted in Figure 6? No explanation nor equation provided. More thorough discussion needed for Figure 6 (line265-271). Why are certain models over/under-estimate the experimental and numerical results? What are the limitations of the model? Why are the numerical and experimental data different?
4. In Figure 7 where the caption states that it is for contact resistance vs thermal conductivity, I cannot find the contact resistance. The figure inset shows two different thermal conductivities (for what?); y axis is effective thermal conductivity of composite; x axis is volume fraction. Therefore, the discussion for Figure 7 does not make sense to me.
5. The authors studied the connection between thermal conductivity and particle size, which is very important (Figure 9). However, the authors did not provide sufficient discussion on the results, i.e., why smaller particle is more efficient. It should also be provided in terms of the comparison with different models and experimental results at varying particle size. How well do they match and why?
6. The manuscript was titled “thermophysical properties” yet only thermal conductivity was probed. If the authors aimed to provide a full spectrum of thermal properties of a polymer composite, traditional analysis such as TGA, DSC, and DMA should be performed. Such characterization techniques can tell the polymer particle interaction, glass transition temperature, melting point etc. Otherwise, the title/abstract should be modified.
7. The introduction seems very fluent and well-structured. However, the discussion of results and the flow of data can be improved.
Minor comments:
1. The authors should perform more characterization on the material and composite. For example, what is the size distribution and morphology of the BaTiO3 particles? How is the particle dispersion within the matrix? SEM images, DLS, or TEM should be performed.
2. Why is the Figure in line 218 Figure 1? Isn’t it Figure 3? What are the axis units in Figure 3?
3. More explanation needed on the reasons for assuming the four boundary conditions (line 170-173)
4. The authors somehow concluded their results (line 174-179) before showing and discussing any data. That paragraph should be put to the later stage.
5. The authors mentioned graphite synthesis, but I did not see it being used in the research.
6. Figure 9 caption wrong.
Comments for author File: 
Comments.docx
The English used in results and discussion sections can be improved. Instead of continuously using "Figure X shows that...", the authors can use other ways to present data. The flow of results and discussion can also be modified. More thorough discussion should be considered.
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Round 2
Reviewer 2 Report
The second version of manuscript improved significantly when compared with first version. So, in my opinion the manuscript can be accepted for publication.
The standard of English must be improved.
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Reviewer 3 Report
Overall, the manuscript has shown some significant improvement but there is still room for better quality. In general, the authors did not give in-depth interpretation of data in various occasions.I herein present several issues that the authors should address in the manuscript.
1. In Figure 6 where the authors compared their results with other models, the authors should provide more insights by the means of why these models and experimental results showed different conductivity. What were the limitations of each model or what was the over-estimation by them.
2. In section 5.3, the explanation for figure 8 was confusing and insufficient. There is no "kch" nor "km" in the figure. Apparently, as contact resistance increases, contact resistance also decreased, which is in contrast to the authors' statement (or the writing is misleading).
3. Caption for figure 9 mentioned comparison between theoretical and experimental results but the figure did not show it. Also, the authors did not provide sufficient discussion on the particle size effect. Aggregation, surface area to volume ratio, surface roughness, etc., should be considered.
Although not much of grammar mistakes was detected, I do think that the authors should polish the writing. For example, the authors started almost every results/discussion paragraph with "Figure X shows that...".
Author Response
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Round 3
Reviewer 3 Report
The authors have kindly addressed all the comments I presented in last two revisions. Therefore, I recommend the manuscript for publication.
