Dielectric Permittivity Model for Polymer–Filler Composite Materials by the Example of Ni- and Graphite-Filled Composites for High-Frequency Absorbing Coatings
, Dmytro Tatarchuk 2, Henning Heuer 1,3 and Yuriy Poplavko 2Round 1
Reviewer 1 Report
For the Manuscript with the title and assignment ID of coatings-1040460; Polar Dielectric Bulk Material in Comparison to Ni- and Graphite-Filled Composites for High-Frequency Absorbing Coatings
This paper claims that the absorption can decrease by using conductive (polymer-metal) and magnetic fillers (polymer-dielectric) when the frequency increases. Beyond that, it is claimed that the absorbing capabilities of composites filled with high-loss dielectric fillers are able to achieve frequency-selective absorption because of electromagnetic and electromechanical resonances resulting from an increment of absorption with increasing frequency. This idea of the study as a specific subject is one of those valuable subjects in the field of multi-disciplinary works of material science and electrical engineering.
In this article, the absorption capabilities of composites filled with high loss dielectric fillers were investigated. The authors argued that as the frequency increases, absorption will be increased, significantly and it is possible to achieve maximum frequency-selective absorption because of electromagnetic and electromechanical resonances.
Even though the problem statement connected to its solution well described in the manuscript. In this study, only dielectric constant dependence on the volume part of the filler for (a) Polymer – Ni samples; (b) polymer – Gr samples as a function of q at different frequencies (Red, 6 MHz; green, 4 GHz; blue, 10 GHz) and dielectric constant as a function of frequency for (a) Polymer – Ni (b) polymer –Gr with various q values are shown in Figure 10 and 11.
Long story, in short, there is no answer/solution about absorption computation and related results. Moreover, the title of the manuscript denotes that "Polar Dielectric Bulk Material in Comparison to Ni- and Graphite-Filled Composites for High-Frequency Absorbing Coatings." It means that the title and the results in the manuscript are not matching and causing confusion to be well organized.
It is clear that this study needs some major corrections (suggestions are listed below):
- A title suitable for the study should be preferred considering the results.
or
- To be compatible with the title, it should be added to the study not only as dielectric constant values but also in terms of absorption rates (in dB).
Also, minor revisions are given below
- 8 should be re-written with the same format of the other equations in the manuscript.
- Figure 2 should have a higher resolution like the others.
- Some notations in the manuscript should be re-written to avoid confusion such as:
- Line 279 () and Line 280 (): greater and less symbols are redundant.
Author Response
Response to Reviewer 1 Comments
Point 1: Even though the problem statement connected to its solution well described in the manuscript. In this study, only dielectric constant dependence on the volume part of the filler for (a) Polymer – Ni samples; (b) polymer – Gr samples as a function of q at different frequencies (Red, 6 MHz; green, 4 GHz; blue, 10 GHz) and dielectric constant as a function of frequency for (a) Polymer – Ni (b) polymer –Gr with various q values are shown in Figure 10 and 11. Long story, in short, there is no answer/solution about absorption computation and related results. Moreover, the title of the manuscript denotes that "Polar Dielectric Bulk Material in Comparison to Ni- and Graphite-Filled Composites for High-Frequency Absorbing Coatings." It means that the title and the results in the manuscript are not matching and causing confusion to be well organized.
A title suitable for the study should be preferred considering the results. To be compatible with the title, it should be added to the study not only as dielectric constant values but also in terms of absorption rates (in dB).
Response 1: You are right, we put a general idea in the title, indeed, it would be better to specify the title so that our results correspond to the title. Now the title is “Dielectric Permittivity Model for Polymer-Filler Composite Materials by the Example of Ni- and Graphite-Filled Composites for High-Frequency Absorbing Coatings”
Point 2: 8 should be re-written with the same format of the other equations in the manuscript.
Response 2: Formula 8 has been rewritten with the same format.
Point 3: Figure 2 should have a higher resolution like the others.
Response 3: Now Figure 2 has a higher resolution and sizes.
Point 4: Some notations in the manuscript should be re-written to avoid confusion such as:
Line 279 () and Line 280 (): greater and less symbols are redundant.
Response 4: Notations with great and small symbols – formula of Zin has been replaced by words «formula 2».
Author Response File: 
Author Response.docx
Reviewer 2 Report
Dear Authors,
The research topic seems to me relevant, so the results obtained may be of interest to the readers of the journal.
Unfortunately, it should be noted that 13 of the 17 sources in References are self-citations, which in my opinion is not acceptable for Coatings. At the same time, a large number of well-known and cited papers are devoted to this topic. In this regard, I recommend supplementing the Introduction section with appropriate emphasis and reducing the number of self-citations to an acceptable minimum.
It is not clear whether the graphs shown in Figures 2, 4-6 are experimental or calculated, or they are taken from the literature data. I think this needs to be clarified.
How exactly were the characteristics of experimental samples measured? The authors did not indicate the equipment used (the model and the manufacturer of a panoramic meter or other devices), and also did not specify the parameters of the rectangular waveguide (width and height) and the dimensions of the samples under study. It is known that measurement methods based on a rectangular waveguide are narrowband, and therefore each frequency band (X, Ku, Ka and other ranges) requires its own measuring waveguide, and, moreover, rectangular waveguides cannot be manufactured for the 6 MHz frequency indicated by the authors.
The number of experimental points on the dependences of the permittivity, in my opinion, is too small for a reliable comparison with the theoretical dependences.
Nevertheless, despite the presence of these shortcomings, I consider it possible to publish this work in the Journal when correcting them.
Author Response
Response to Reviewer 2 Comments
Point 1: Unfortunately, it should be noted that 13 of the 17 sources in References are self-citations, which in my opinion is not acceptable for Coatings. At the same time, a large number of well-known and cited papers are devoted to this topic. In this regard, I recommend supplementing the Introduction section with appropriate emphasis and reducing the number of self-citations to an acceptable minimum.
Response 1: Source 13 was replaced by another source - Langhe D.; Ponting M., Manufacturing and Novel Applications of Multilayer Polymer Films: William Andrew Publishing, 2016, p. 250. Source 17 was deleted to avoid self-citations. The introduction section was supplemented with appropriate emphasis, that there are a lot of well-known and cited papers devoted to this topic.
Point 2: It is not clear whether the graphs shown in Figures 2, 4-6 are experimental or calculated, or they are taken from the literature data. I think this needs to be clarified.
Response 2: Graph from the Figure 2b – is taken from the 4th source, it was clarified. Figures 4(a) and 4(b) are not experimental or calculated data, but are generalized representations of two main models describing permittivity dispersion. Figures 5 and 6 are taken from the literature data – 14th source, it was also clarified by the link.
Point 3: How exactly were the characteristics of experimental samples measured? The authors did not indicate the equipment used (the model and the manufacturer of a panoramic meter or other devices), and also did not specify the parameters of the rectangular waveguide (width and height) and the dimensions of the samples under study. It is known that measurement methods based on a rectangular waveguide are narrowband, and therefore each frequency band (X, Ku, Ka and other ranges) requires its own measuring waveguide, and, moreover, rectangular waveguides cannot be manufactured for the 6 MHz frequency indicated by the authors.
Response 3: The description of measurements was added in “2.3.4 Method of reflection–transmission energy coefficients”. Also the name of VSWR meter P2-57 was added. Parameters of waveguide and samples were clarified. An RLC circuit was used for measurements in the 3 MHz frequency range. Description of this experiment, figures was added in “2.3.5 Serial RLC circuit method of dielectric constant measurement”.
Point 4: The number of experimental points on the dependences of the permittivity, in my opinion, is too small for a reliable comparison with the theoretical dependences.
Response 4: As for the fact that there are few measurements, this is not the case. We have few points on the graphs, but 10 samples were measured at each point. Apparently, it should be said about this, it is necessary to write the spread of data by experimental points +-10% and add it on graphs 14 and 15.
Reviewer 3 Report
see attached file
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewer 3 Comments
Point 1: The only question I have how the chapter related to dielectric dispersion in different ferroelectric materials (PMN, BaTiO3, TGS and Rochelle salt etc.) are relevant to the topic of the manuscript and presented experimental results. This is an open question for authors and I would recommend the manuscript for publication.
Response 1: These materials are relevant to the topic of manuscript because of their heigh value of dielectric constant. Also this part of the article describes the nature and reason of such a high value.
Round 2
Reviewer 2 Report
Dear Authors!
Thank you for your edits. Nevertheless, I believe that the first of the comments has not been fully taken into account, since the percentage of self-citation in the work is still excessive for a high-rating international journal and amounts to 12 references out of 16 given in the list of references. Thus, I am convinced that without a significant reduction in the number of self-citations with a simultaneous increase in the number of references to well-known articles and monographs in this area, the article cannot be accepted for publication.
Author Response
Response to Reviewer 2 Comments
Point 1: Nevertheless, I believe that the first of the comments has not been fully taken into account, since the percentage of self-citation in the work is still excessive for a high-rating international journal and amounts to 12 references out of 16 given in the list of references. Thus, I am convinced that without a significant reduction in the number of self-citations with a simultaneous increase in the number of references to well-known articles and monographs in this area, the article cannot be accepted for publication..
Response 1: 5 sources have been replaced: № 6,8,10,11,16 to avoid self-citation.
Source 6 has been replaced by well-known book: “Ye Z-G. (Ed.), Handbook of Advanced Dielectric, Piezoelectric and Ferroelectric Materials; Woodhead Publishing, 2008; p. 1096”.
Source 8 has been replaced by also well-known monograph: “Mailadil T.S., Dielectric Materials for Wireless Communication, Elsevier: 2008, p.688”.
Source 10 has been replaced by dielectric polymer materials-specific book: “Dang Z.-M. (Ed.), Dielectric Polymer Materials for High-Density Energy Storage: William Andrew Publishing, 2018, p. 500”.
Source 11 has been replaced by article: “Feng M.; Chi O.; Feng Y.; Zhang Y.; Zhang T.; Zhang C.; Chen Q.; Lei Q. High energy storage density and efficiency in aligned nanofiber filled nanocomposites with multilayer structure, Composites Part B: Engineering, 2020, 198 (108206); doi: 10.1016/j.compositesb.2020.108206”.
Source 16 has been replaced by well-known book: “Levitskaya T.; Sternberg B. Electrical Spectroscopy of Earth Materials, Elsevier: USA 2019, p. 330”.
Thank you for your review and your comments.
