Properties of Ultra-High Molecular Weight Polyethylene Produced by Cyclic Impact Compaction and Reinforced with Graphene Nanoplatelets and Single-Walled Carbon Nanotubes

Round 1

Reviewer 1 Report

Manuscript ID: jcs-2504106
Type of manuscript: Article
Title: Cyclic Impact Compaction of an Ultra High Molecular Weight Polyethylene (UHMWPE) Powder with Additives of Nanoscale Detonation Carbon and Carbon Nanotubes by Alexandr Shtertser, Boris Zlobin, Victor Kiselev, Sergei Shemelin, Vladislav Shikalov, Evgenij Karpov and Konstantin Ivanyuk

 

Although the authors already have several works of this type in this area, and they are all from approximately the same field of research, where there are individuals with a satisfactory h index, the research is interesting but insufficiently explained. I ask that this article be clarified in a multidisciplinary manner and connected with works that have the same and similar research materials, on several different aspects: chemical (chemical formulas and structures of pure materials to the possible structure of composites..), physical (citing physical laws in which they are clearly seen properties of interest), modeling explanations (mathematical and numerical explanations of tendencies), the possible application of these materials (I emphasize the medical application) which has already been realized with positive and negative implications.

The authors should explain in more detail the causes that lead to changes in the investigated characteristics. In other words, the Authors should explain in more detail the causes that lead to changes in the investigated characteristics. Therefore, they should introduce a multidisciplinary review in the introduction. Then they should have a theoretical chapter in which the theory is presented, in which the properties that lead to changes in the properties in a certain way are pointed out later in the composite. The discussion should link the theory and the results they gave with relevant explanations. In the conclusion, conclusions should be given on the confirmation or rejection of the existing theoretical aspects. I insist on that because the work would gain in quality. Many of the considerations that would be included are at low levels of education, but would emphasize the importance and relevance of this type of research.

Introduce abbreviations from the introduction

Enter abbreviations only once, check , eg NDC

Technical question putting % on all numbers, abstract 6,4%

The line 43 is one example where you need to correct your English. They don't leave the “are” with “one”.

The line 153 authors should provide additional information regarding used test standard, testing speed, etc..                                                                        

Give an explanation to the tables that you have in the discussion          

Discussion

In the discussion, you gave all the results that should be a description of the tables that are in the results. Transfer the results from the discussion to the tables...

Write the discussion so that it is related to the multidisciplinary nature of the work..eg why hardness increases, friction and roughness decrease. Give the reasons from chemical (formation of newly formed bonds) to physical (existence of additional forces of interaction between these types of Ions), to confirmation of existing models...

The emphasis should be on relating the theory you provided in the front of the article to the results obtained with justification of the patterns that occurred in the given composites. I emphasize that you should have a justification about the agreement/disagreement between the experiment and the theory.

Avoid (line from 241 to 244) in the discussion, because you didn't deal with the electrical characteristics...you can add this to the introduction, as an interesting thing that can be investigated in such composites.

In the discussion, they should give a more detailed explanation of the causes that lead to changes in the examined properties. To connect the experiment with the theory and to answer the questions of why it comes

the decrease in properties... occurs due to the absence/existence of interactions between matrices and fillers. How the measurement conditions change/do not change the characteristics

Conclusion

In the conclusion (lines 253-255), you repeated the method of preparing the experiment. This method of preparation should not stand in the conclusion of the experiment. if you want to emphasize the connection with obtaining some qualities, you have to have it through the work and also in the conclusion

The conclusion should contain the final connections made in the discussion. Gained/lost characteristics of the material due to addition/subtraction with changes in the structure of the material in a certain way lead to the increase/loss of this and that property...with the possibility of practical use for this and that.

This would allow someone outside the field to make practical use of the given research

 

 Moderate editing of English language required

Author Response

Responses to the Reviewer 1

The authors are grateful to the Reviewer for carefully reading the work and comments made. Below are the responses to the comments. The amendments and additions in the revised text are in red font.

1) Although the authors already have several works of this type in this area, and they are all from approximately the same field of research, where there are individuals with a satisfactory h index, the research is interesting but insufficiently explained. I ask that this article be clarified in a multidisciplinary manner and connected with works that have the same and similar research materials, on several different aspects: chemical (chemical formulas and structures of pure materials to the possible structure of composites..), physical (citing physical laws in which they are clearly seen properties of interest), modeling explanations (mathematical and numerical explanations of tendencies), the possible application of these materials (I emphasize the medical application) which has already been realized with positive and negative implications.

Response: In the revised text, the introduction has been expanded and new links have been added to the list of references. And, in lines 109-110 it is indicated that the NDC nano-additive used by us does not have cytotoxicity and can be applied in the manufacture of composites for medicine. However, in our opinion, in the format of an article that is not a review, but is devoted to a specific experimental study of the effect of certain carbonaceous additives on the properties of a polymer, it is not advisable to conduct a deep multidisciplinary analysis on the topic. Moreover, such an analysis, including chemical formulas and physical laws has already been carried out in a number of articles, see, for example, ref. [1,10,24,30]. As for biomedical aspects, again in the introduction there are links to publications on this topic, for example, Ref. [2,3,4,5,30]. The purpose of this work was only to make samples from UHMWPE with nano-additives by the CIC method, which is not yet used in industry. In fact, the effect of such additives as NDC and single-walled nanotubes (the product of OCSiAl Company) on the properties of the resulting composite has not yet been studied. In our opinion, the experimental results obtained are new and may be of interest to our colleagues working in the field of theoretical modeling of the mechanical behavior of polymer-based composites.   

2) The authors should explain in more detail the causes that lead to changes in the investigated characteristics. In other words, the Authors should explain in more detail the causes that lead to changes in the investigated characteristics. Therefore, they should introduce a multidisciplinary review in the introduction. Then they should have a theoretical chapter in which the theory is presented, in which the properties that lead to changes in the properties in a certain way are pointed out later in the composite. The discussion should link the theory and the results they gave with relevant explanations. In the conclusion, conclusions should be given on the confirmation or rejection of the existing theoretical aspects. I insist on that because the work would gain in quality. Many of the considerations that would be included are at low levels of education, but would emphasize the importance and relevance of this type of research.

Response: In the revised text, we have expanded the introduction and selected additional references that characterize the multidisciplinary nature of the topic. However, the main emphasis was still placed on carbonaceous additives in UHMWPE. We tried to emphasize that different authors obtained different, sometimes opposite results on the effect of additives on the mechanical properties of the polymer. Although our work is purely experimental and did not involve the construction of a theoretical model, nevertheless, the Theoretical Considerations subsection is inserted as a theoretical chapter in the Discussion section.

3) Introduce abbreviations from the introduction.

Response: I'm sorry, but the remark is unclear. What is  necessary, to “introduce … in” or “remove … from” abbreviations?

4) Enter abbreviations only once, check , eg NDC.

Response: Changes have been made to the text

5) Technical question putting % on all numbers, abstract 6,4%.

Response: Changes have been made to the text

6) The line 43 is one example where you need to correct your English. They don't leave the “are” with “one”.

Response: Changes have been made. In the revised text, lines 42-44 are replaced by lines 71-79.

7) The line 153 authors should provide additional information regarding used test standard, testing speed, etc..  

Response:  The sentence in line 153 is supplemented with the words "in accordance with the Russian standard GOST 9012-59" (line 185 now). The measurement parameters (ball diameter, load, exposure time) were specified in the "Results" section in lines 253-256 immediately after Fig.4.                                                                     

8) Give an explanation to the tables that you have in the discussion.

Response: For convenience in interpreting the results, Table 4 is inserted in the Discussion section, which reflects the changes in mechanical and tribological properties associated with additives.          

9)Discussion

In the discussion, you gave all the results that should be a description of the tables that are in the results. Transfer the results from the discussion to the tables...

Response: Table 4 is inserted in the Discussion section, which reflects the changes in mechanical and tribological properties associated with additives.     

10) Write the discussion so that it is related to the multidisciplinary nature of the work..eg why hardness increases, friction and roughness decrease. Give the reasons from chemical (formation of newly formed bonds) to physical (existence of additional forces of interaction between these types of Ions), to confirmation of existing models...

The emphasis should be on relating the theory you provided in the front of the article to the results obtained with justification of the patterns that occurred in the given composites. I emphasize that you should have a justification about the agreement/disagreement between the experiment and the theory.

Response: As we noted above, the authors of this work are experimentalists and the work itself is purely experimental and did not involve the construction of a theoretical model. There are many works in which theoretical specialists conduct modeling, including numerical modeling, of the behavior of polymers and composites based on them under mechanical loading. See, for example, the Ref. [46]. Nevertheless, we have tried to explain the results obtained on the basis of simple physical reasoning. To do this, a subsection Theoretical considerations is inserted into the Discussion section.

11) Avoid (line from 241 to 244) in the discussion, because you didn't deal with the electrical characteristics...you can add this to the introduction, as an interesting thing that can be investigated in such composites.

Response: The mentioned lines are removed from the text

12) In the discussion, they should give a more detailed explanation of the causes that lead to changes in the examined properties. To connect the experiment with the theory and to answer the questions of why it comes

the decrease in properties... occurs due to the absence/existence of interactions between matrices and fillers. How the measurement conditions change/do not change the characteristics.

Response: See the response to remark 10.

13) Conclusion

In the conclusion (lines 253-255), you repeated the method of preparing the experiment. This method of preparation should not stand in the conclusion of the experiment. if you want to emphasize the connection with obtaining some qualities, you have to have it through the work and also in the conclusion

The conclusion should contain the final connections made in the discussion. Gained/lost characteristics of the material due to addition/subtraction with changes in the structure of the material in a certain way lead to the increase/loss of this and that property...with the possibility of practical use for this and that.

This would allow someone outside the field to make practical use of the given research

Response: The text of the Conclusion has been changed. The lines concerning the compaction details have been deleted.

 

 

14) Comments on the Quality of English Language

 Moderate editing of English language required

Response: English has been edited.

 

Author Response File: Author Response.docx

Reviewer 2 Report

attention the Keyword format

Line 27 should not be capitalized

Line 31 adds the full name of the abbreviation

152 line, supplementing the margin of error in the table

Author Response

Responses to the Reviewer 2

The authors are grateful to the Reviewer for carefully reading the work and comments made. Below are the responses to the comments. The amendments and additions in the revised text are in red font.

 

Comments and Responses:

1) attention the Keyword format  Response: Corrections have been made.

2) Line 27 should not be capitalized   Response: Corrections have been made.

3) Line 31 adds the full name of the abbreviation  Response: The full name of the abbreviation PTFE has been added.

4) 152 line, supplementing the margin of error in the table  Response: The margins of error are inserted in Table 1.

Author Response File: Author Response.docx

Reviewer 3 Report

Overall, I find the study to be promising and potentially valuable for the scientific community. While we recognize the potential value of your study, we would like to request additional results and improvements to enhance the quality of the paper. In addition, to ensure the scientific rigor and further enhance the merit of the work, we have compiled a set of technical questions and constructive comments that we would like you to address.

 

General comments:

-The current set of results presented in the paper appears to be insufficient to fully support your findings. We encourage you to provide more comprehensive experimental data, such as additional measurements, observations, or analyses, to strengthen the validity of your conclusions. This will help to improve the robustness and reliability of your research.

-I recommend enhancing the overall structure of the paper for better clarity and organization. Consider providing a clear and concise introduction that outlines the research objectives and contextualizes the significance of UHMWPE composites with nanoscale additives. Ensure that the methodology section is detailed enough to allow for reproducibility and clarity of the experimental procedures. Additionally, a clear and logical flow in presenting the results, discussions, and conclusions will greatly improve the readability and understanding of your work. 

 

Technical comments:

-what is th novetly by comparing with the published work in materials journal "Cyclic Impact Compaction of an Ultra High Molecular Weight Polyethylene (UHMWPE) Powder and Properties of the Compacts".

-Could you provide more detailed information on the characterization techniques used to assess the mechanical properties, such as hardness, wear resistance, tensile strength, and coefficient of friction? Additionally, please elaborate on the accuracy and repeatability of these measurements.

-It would be helpful to gain a better understanding of the dispersion and interfacial bonding between the nanoscale additives (Nanoscale Detonation Carbon - NDC and Single-Walled Carbon Nanotubes - SWCNTs) and the UHMWPE matrix. Please discuss the steps taken to ensure a uniform distribution and strong bonding of the additives within the composite material.

-Have you explored strategies or approaches to optimize the concentration or formulation of the additives, considering the observed decrease in tensile strength and elongation? Additionally, please elaborate on how adjusting the concentration or combination of additives could potentially influence the mechanical properties of the composites.

-It would be beneficial to gain insights into the wear mechanisms involved, given the reduction in wear with the addition of NDC and SWCNTs. Have you conducted any analysis or observations to understand the specific interactions between the nanoscale additives and the wear surfaces?

-add more reference related to this work as: Mechanical properties of a biocomposite based on carbon nanotube and graphene nanoplatelet reinforced polymers: Analytical and numerical study. Journal of Composites Science.

-In terms of scalability and practical implementation, have you considered the feasibility of producing UHMWPE composites with nanoscale additives on a larger scale? Please discuss any challenges or considerations related to manufacturing processes, cost-effectiveness, or compatibility with existing industrial techniques.

-Considering the potential applications of UHMWPE composites with enhanced properties, have you conducted any preliminary investigations or discussions on the long-term durability, stability, and aging effects of these composites? Please address how environmental conditions or operational factors could impact the performance and longevity of the materials.

Author Response

Responses to the Reviewer 3

The authors are grateful to the Reviewer for carefully reading the work and comments made. Below are the responses to the comments. The amendments and additions in the revised text are in red font.

 

General comments:

-The current set of results presented in the paper appears to be insufficient to fully support your findings. We encourage you to provide more comprehensive experimental data, such as additional measurements, observations, or analyses, to strengthen the validity of your conclusions. This will help to improve the robustness and reliability of your research. 

-I recommend enhancing the overall structure of the paper for better clarity and organization. Consider providing a clear and concise introduction that outlines the research objectives and contextualizes the significance of UHMWPE composites with nanoscale additives. Ensure that the methodology section is detailed enough to allow for reproducibility and clarity of the experimental procedures. Additionally, a clear and logical flow in presenting the results, discussions, and conclusions will greatly improve the readability and understanding of your work. 

Response: In the revised article, a broader analysis of the literature is made, the description of experiments is supplemented and a new subsection “Theoretical considerations” is inserted in the “Discussion” section.

 

Technical comments:

-what is th novetly by comparing with the published work in materials journal "Cyclic Impact Compaction of an Ultra High Molecular Weight Polyethylene (UHMWPE) Powder and Properties of the Compacts". Response: The article in the journal “Materials” is mainly devoted to the search for optimal technological modes for obtaining compacts based on UHMWPE and it shows the strength properties of samples made of pure polymer, without additives. Tribological properties were not investigated at all in this work. And the present article describes  comparative studies of the mechanical and tribological properties of compacts made of pure polymer and polymer with carbon nanoadditives. In addition, composites based on UHMWPE with additives of NDC and single-walled carbon nanotubes produced by OCSiAl Company, moreover, produced by the CIC method, have not been previously studied at all. The novelty is emphasized in the last paragraph of the Introduction

-Could you provide more detailed information on the characterization techniques used to assess the mechanical properties, such as hardness, wear resistance, tensile strength, and coefficient of friction? Additionally, please elaborate on the accuracy and repeatability of these measurements. Response: Details of hardness measurements and tensile tests are given in lines 184-188, 219-220 and in Figure 3. Details of tribological tests are given in lines 189-192 and 253-256. As for accuracy and repeatability, Table 1 and Table 2 are supplemented with the data, that were previously omitted.

-It would be helpful to gain a better understanding of the dispersion and interfacial bonding between the nanoscale additives (Nanoscale Detonation Carbon - NDC and Single-Walled Carbon Nanotubes - SWCNTs) and the UHMWPE matrix. Please discuss the steps taken to ensure a uniform distribution and strong bonding of the additives within the composite material. Response: An additional subsection, “Theoretical Reasoning”, is inserted into the “Discussion” section, where the issue of interface connection is considered and its impact on the properties of the composite is assessed. The issue of homogeneous distribution of nanoparticles is very complex and requires a separate thorough study, which is planned in the future. We should add that it is not possible to break up nanotube conglomerates, for example, by ultrasound. And the rotating blade method used in the article, in our opinion, works better.

-Have you explored strategies or approaches to optimize the concentration or formulation of the additives, considering the observed decrease in tensile strength and elongation? Additionally, please elaborate on how adjusting the concentration or combination of additives could potentially influence the mechanical properties of the composites. Response: So far, we have not optimized the composition and concentrations of additives. Our work in this direction is just the beginning. The content of 0.5% of nano-additives was taken because it is often used in such composites according to the literature. Regarding the effect of the concentration of additives, some arguments are given in the new subsection “Theoretical considerations”.

-It would be beneficial to gain insights into the wear mechanisms involved, given the reduction in wear with the addition of NDC and SWCNTs. Have you conducted any analysis or observations to understand the specific interactions between the nanoscale additives and the wear surfaces? Response: The question of the mechanism of wear of composites is very complex and also requires separate studies. Some qualitative considerations based on the "pulling out" of nanoparticles from the polymer are given at the end of the subsection Theoretical considerations.

-add more reference related to this work as: Mechanical properties of a biocomposite based on carbon nanotube and graphene nanoplatelet reinforced polymers: Analytical and numerical study. Journal of Composites Science. Response: Thanks for the recommendation. We have studied this interesting article and added it to the list of references at number 46, see also lines 401-403.

-In terms of scalability and practical implementation, have you considered the feasibility of producing UHMWPE composites with nanoscale additives on a larger scale? Please discuss any challenges or considerations related to manufacturing processes, cost-effectiveness, or compatibility with existing industrial techniques. Response: These issues are not discussed in this article. Now we are working on a laboratory installation on which it is possible to make compacts with a diameter of up to 60 mm and a thickness of about 20 mm. In our opinion, it is quite realistic to create an industrial installation for mass production of UHMWPE products and composites based on it by the CIC method. As we indicated earlier in work [23], one of the main problems to be solved in industrial production is the durability of die tooling, which is subjected to shock loads.  

-Considering the potential applications of UHMWPE composites with enhanced properties, have you conducted any preliminary investigations or discussions on the long-term durability, stability, and aging effects of these composites? Please address how environmental conditions or operational factors could impact the performance and longevity of the materials. Response: Since we have so far produced and studied only laboratory samples, it was not possible to investigate the materials obtained in terms of long-term strength, stability of properties, etc. in relation to specific industrial or medical applications. Such studies will necessarily be carried out in the presence of an industrial partner interested in the CIC technology.   

 

 

Author Response File: Author Response.docx

Reviewer 4 Report

The current paper reports on ‘cyclic impact compaction of UHMWPE powder with nanoscale additives”. First of all, the paper needs moderate to extensive English revision. In current form the foreseen meaning of many sentences was lost due to poor English. Then, the paper is poorly organised with limited experiments and without proper presentation of the experimental facts. The discussion section is very poor where the authors tried to justify their results in view of literature without proper experimental proof. Based on my assessment, I suggest major revision of this paper.

 

The other comments are as follows:

1.     The title must be revised for better clarity; and focused to reflect the content of the current manuscript.

2.     The abstract must be revised in a focused way, particularly in relation to foreseen meaning. For example, wear resistance test (line 17), decrease in wear (line 19) which are not proper way of expressing scientific meaning.

3.     Instead of group citation, (Line 31 and 33 and others) try to make it more specific, so that the info is more credible in your paper.

4.     The last paragraph of the introduction section must be re-written, which should reflect the objective of the present work; NOT the methodology.

5.     What standard (ASTM?) was used to investigate the tensile testing?

6.     It is suggested to include the micrographs of loose and mixed powders were additives.

7.     Fig. 4: Was the samples polished? Coated? prior to SEM? If yes, that needs to be mentioned in the experimental sections.

8.     Much higher resolution micrographs are required to explicitly show the distribution of additives in the matrix as well as porosities, if there is any. The current micrographs are vague and not convincing at all, as addition of additives is the main essence of the present work.

9.     Fig. 5 a, b and c may be combined in a single fig. with figure legend, which will make it easier to compare the graphs.

10.  Table 3: Better to represent it as wear rate or coefficient of wear to have any meaningful significance.

11.   It is highly recommended to include the images of wear tracks, evolution of coefficient of friction with time and analysis of transfer material on the counterbody.

12.  On what basis, steel ball was chosen as counterbody? The issue with the steel ball is that, there will be transfer of materials, which will highly affect both wear rate and coefficient of friction.

13.  Interestingly in the discussion section, there is hardly any original discussion form the authors except repeating the results and  justifying it in view of literature. For example, Line 236: there is no data/experimental proof regarding adhesion strength of the matrix and carbon particles.

14.  The last paragraph of the discussion section; Better to omit this section as the authors did not perform any electrical resistance tests in their present work.

Moderate editing of English language required

Author Response

Responses to the Reviewer 4

The authors are grateful to the Reviewer for carefully reading the work and comments made. Below are the responses to the comments. The amendments and additions in the revised text are in red font.

 

General comment.

The current paper reports on ‘cyclic impact compaction of UHMWPE powder with nanoscale additives”. First of all, the paper needs moderate to extensive English revision. In current form the foreseen meaning of many sentences was lost due to poor English. Then, the paper is poorly organised with limited experiments and without proper presentation of the experimental facts. The discussion section is very poor where the authors tried to justify their results in view of literature without proper experimental proof. Based on my assessment, I suggest major revision of this paper.

Response: After revision, the article has been increased in volume. The introduction has been expanded, the list of cited literature has been significantly increased, clarifying information has been added to all sections, the “Discussion” section is divided into two subsections and significantly increased. We also tried to improve our English as much as we could.

The other comments:

1. The title must be revised for better clarity; and focused to reflect the content of the current manuscript. Response: The title of the manuscript has been changed.
2. The abstract must be revised in a focused way, particularly in relation to foreseen meaning. For example, wear resistance test (line 17), decrease in wear (line 19) which are not proper way of expressing scientific meaning. Response: The abstract is revised.
3. Instead of group citation, (Line 31 and 33 and others) try to make it more specific, so that the info is more credible in your paper. Response: The group citation in this case, and in some other cases, is done to highlight publications devoted to one topic. For some readers interested in a specific topic, this is convenient. This makes it easier to choose the literature that a researcher working in a certain direction needs
4. The last paragraph of the introduction section must be re-written, which should reflect the objective of the present work; NOT the methodology. Response: The last paragraph is re-written.
5. What standard (ASTM?) was used to investigate the tensile testing? Response: Tensile tests were carried out according to the Russian standard GOST 11262-2017 (see the lines 187-188).
6. It is suggested to include the micrographs of loose and mixed powders were additives. Response: To our deep regret, during the research we did not take photos of the original powders and their mixtures. This is our omission. However, now we cannot make mixtures and take photos, because the powders have run out and it takes time to purchase UHMWPE and carbon nanotubes, and manufacture NDC. We really hope that this omission will not crucially reduce the value of the article.
7. Fig. 4: Was the samples polished? Coated? prior to SEM? If yes, that needs to be mentioned in the experimental sections. Response: The samples were polished before SEM, the STRUERS Tegramin-20 sample preparation station was used for this. After polishing, the surface was covered with a layer of gold about 1 nm (see the lines 195-197).
8. Much higher resolution micrographs are required to explicitly show the distribution of additives in the matrix as well as porosities, if there is any. The current micrographs are vague and not convincing at all, as addition of additives is the main essence of the present work. Response: In the revised article, there are new optical and SEM photos.
9. Fig. 5 a, b and c may be combined in a single fig. with figure legend, which will make it easier to compare the graphs.  Response: Figures 5a, b, c are combined into one diagram
10. Table 3: Better to represent it as wear rate or coefficient of wear to have any meaningful significance. Response: Since the friction path of 100 m is indicated right in front of the table, the wear figures indicated in the table obviously refer to this path and mean the wear rate (in mm3 per 100m)
11. It is highly recommended to include the images of wear tracks, evolution of coefficient of friction with time and analysis of transfer material on the counterbody. Response: In this paper, we did not aim at a detailed study of the wear process. Such studies require separate efforts combined with a more thorough investigations of the microstructure and, in our opinion, should be focused on a separate publication. In this paper, one of the approaches to the manufacture of composites was considered and their properties primarily important from the point of view of applications were studied.
12. On what basis, steel ball was chosen as counterbody? The issue with the steel ball is that, there will be transfer of materials, which will highly affect both wear rate and coefficient of friction. Response: We can only give the same answer to this remark as to the previous one
13. Interestingly in the discussion section, there is hardly any original discussion form the authors except repeating the results and  justifying it in view of literature. For example, Line 236: there is no data/experimental proof regarding adhesion strength of the matrix and carbon particles. Response: The Discussion section has been supplemented and the Theoretical considerations  subsection has been inserted there. We hope that the added material improves the quality of the article in the direction of interpreting the results obtained.
14. The last paragraph of the discussion section; Better to omit this section as the authors did not perform any electrical resistance tests in their present work. Response: The mentioned paragraph is omitted in the revised version.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

the manuscript can be accepted in present form

Reviewer 3 Report

The paper can be accepted in this form.

 

Reviewer 4 Report

Accept in present form

Minor editing of English language required