Wood-Based Composites with High Electromagnetic Interference Shielding Effectiveness and Ultra-Low Reflection

Round 1

Reviewer 1 Report

The work is experimental and concerns a very important and current problem of protection against electromagnetic pollution. The authors constructed a lightweight Ni / Wood / Ni composite with an interlayer structure using a simple electroless coating method. The obtained composite was characterized by surface smoothness and roughness <9 μm. It was empirically demonstrated that in the L band the effectiveness of electromagnetic shielding was 94.1 dB (nickel plating three times in 20 minutes). The efficiency of absorption in this band was 39 dB. The tests confirmed that the produced material is suitable for the production of ultra-thin wood-based materials that can be used in construction and aviation.

I rate the work very highly due to the comprehensive and original approach to the problem. The biggest disadvantage of the work is the lack of a description of the actions taken and the lack of explanation of some issues.

 Below are my detailed comments:

1. Chapter 1: Please clearly state the purpose and scope of the work as well as the solution innovation.

2. Chapter 2: Please explain why the following materials were used: NiSO 4 · 6H 2 O, NaH 2 PO 2 · H 2 O, Na 3 C 6 H 5 O 7 · H 2 O, CH 4 N 2 S and NH 3 H 2 O 30 mL / L?. Please explain the physical meaning of the variable parameters in the formulas (1) - (3). Unless otherwise reserved, the authors can further describe the sample preparation procedure.

3. Chapter 3.1-3.2: Test results are described in detail. I have no comments. I propose to change the background of spatial charts from black to white.

4. Chapter 3.3-3.4: Please describe what method was used to determine Contact angle, Electrical conductivity and Electromagnetic shielding efficiency.

5. Chapter 4. I believe that such extensive research should have extensive conclusions. I propose to expand. There are no directions for further work at the end.

 

Author Response

Dear editor,

Thank you for your message. The manuscript was revised according to your advice. I made some additional changes and marked those changes with red color in revised manuscript. I am looking forward to your reply.

 

 

With best wishes,

 

Yanfei PAN Ph.D.

College of Materials Science and Art Design

Inner Mongolia Agricultural University

Hohhot, 010018

P.R. China

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper from Pan et al. exploits a LbL approach for preparing Ni/Wood/Ni composite by means of an electroless plating method; wood is employed as a substrate for electromagnetic interference shielding. The manuscript shows some novelty, though the text needs some significant revisions and integrations. Therefore, major revision is suggested.

Some comments and suggestions are listed as follows:

- Introduction: please reorganized it, better stressing the current state-of-the-art and the step forward proposed here. Indeed, from line 44 onwards, it is a mere list of papers ("First author et al.") and the main outcome, without a rational development/progress

- lines 132-138: please detail the experimental parameters adopted for each characterization technique

- line 140: it is not clear if the authors refer to equations 1-4 or not. 

- it could be very useful to combine the information gathered from  laser confocal microscopy with AFM (atomic force microscopy) measurements

- it could be useful to perform dynamic contact angle values, hence measuring advancing and receding contact angles, and finally calculating the hysteresis that can be directly related to the surface roughness

- the EMI shielding performances of the proposed systems should be compared to other systems already reported in the literature: in particular, a table collecting the EMI shielding data of the present manuscript and other materials should be added to the revised text.

- apart from Ref 2, all the other references refer to valuable Chinese groups. Please extend the references to not Chinese scholars. Coatings is an international journal!

Author Response

Dear editor,

Thank you for your message. The manuscript was revised according to your advice. I made some additional changes and marked those changes with red color in revised manuscript. I am looking forward to your reply.

 

 

With best wishes,

 

Yanfei PAN Ph.D.

College of Materials Science and Art Design

Inner Mongolia Agricultural University

Hohhot, 010018

P.R. China

Author Response File: Author Response.pdf

Reviewer 3 Report

OVERVIEW

The authors deal with issues related to electromagnetic pollution and the possibilities of eliminating electromagnetic radiation using suitable shielding material. The authors produced a light and thin nickel-wood-nickel composite material for electromagnetic interference shielding. For the production of composite shielding material, the authors used a simple electroless plating method while applying a layer of nickel on both sides of natural wood as a substrate. The authors experimented with the time of applying the Ni layer to the wood and the number of layers deposited on the wood surface. The authors characterized the electro-physical properties of the Ni-wood-Ni composite material by measuring electrical conductivity, scanning electron microscopy, hydrophobicity and S-parameters. In conclusion, the authors state that the shielding efficiency of the Ni-wood-Ni composite material is 94.1 dB, while the shielding efficiency by absorption dominates.

POSITIVE ASPECTS

1. Based on a literature review, the authors point to the issue of EMI environmental pollution.

2. Based on a literature review, the authors present the various techniques and materials used to prepare EMI shielding.

3. The authors prepared a sandwich-structured EMI shielding material made of nickel-plated porous wood using the electroless plating method and examined its electro-physical properties.

ISSUES

The presented work is useful but has some issues that need to be removed. I have a few comments that can be used to improve the article.

Minor issues

1. In line 112, there is only a list of chemical formulas without further description and therefore appears redundant. Is that right?

2. The list of chemical formulas given in line 112 is repeated in a sentence in line 124.

3. Redundant spaces must be removed from the manuscript, for example, line 129. Correct accordingly throughout the text.

4. Line 140 is missing the equation the authors intend to give.

5. The symbol of the physical unit must write using straight (normal) font according to ISO 31-4 (ISO 80000-5: 2007); e.g. (dB) for decibel. Corrections need to be done throughout the article.

6. A space should follow the comma separating the numbers see line 233.

Major issues

1. The authors list the section thickness of wood-based composites in Table 1. Are the numerical values in Table 1 from a single measurement? When specifying layer thicknesses, it is advisable to measure them in several places to obtain a statistical profile of the layer thickness. That's why I recommend to including in the text of the manuscript (or in Table 1) the number of layer thickness measurements, the average thickness value, and the measurement error (or uncertainty). Similarly, this applies to the surface roughness mentioned in the manuscript and in Table 2.

2. In Figure 5 b-l, some letter markings are not visible. Correct all text accordingly.

3. In Figure 9, the authors present in graphs the SE_T, SE_R, and SE_A shielding efficiencies. According to the mentioned frequency dependences of the SE components, it can be concluded that formula (4) is not valid. For example, from Figure 9k for five minutes, the values SE_T = 53.1 dB, SE_A = 34.61 dB and SE_R = 0.16 dB can be found. Add a comment to the manuscript about the given fact.

RECOMMENDATIONS

1. I recommend breaking the Introduction section into several paragraphs.

2. The authors state in lines 144 to 145 that: “When the multiple reflections are less than 15 dB (SET), Formula (1) can be simplified as:”. A reference to the literature would be appropriate for this statement.

3. Points 1 to 3 on the EDS spot scanning map are very small - hard to see. I recommend using a suitable technique to highlight points 1 to 3 in Figure 3.

4. Texts in Figures 4b and 4d are hard to read on a dark background. I recommend using a lighter text color for this case.

5. I recommend dividing section 3.2 into several paragraphs.

6. I recommend dividing section 3.4 into several paragraphs.

QUESTIONS

I have five questions for the authors of the article.

1. In line 142, the authors state the abbreviation SEM, commonly used to indicate the term scanning electron microscopy. Is that right? It follows from the context that it is an abbreviation for multiple reflections (SEM). If this is the case, fix it.

2. In lines 163 and 164, the authors present the unusual wording, “...design of different times and different times,...”. Is that okay? If it is wrong, make a correction in the sentence.

3. In line 173, why did the authors use an initial capital T for the definite article?

4. On lines 284, 292 to 294, the authors give different names: electromagnetic shielding efficiency, electromagnetic shielding value, and ideal electromagnetic shielding effect. What is the ideal electromagnetic shielding effect? Add a comment to the manuscript with appropriate reference to the literature.

5. The Ni-Wood-Ni sandwich structure was prepared in solution. What was the water content in the Ni-Wood-Ni sandwich structure before the start of the S-parameters measurement? Did the authors measure the conductivity of dry and wet porous wood without a Ni layer? Can the authors guarantee that the interior of the wood in the Ni-Wood-Ni sandwich contained no moisture or dissolved salts? Add to the manuscript the text for the above questions. Add a comment about the influence of humidity on the S-parameter.

CONCLUSION

I find this article helpful. Regretfully, the paper cannot be accepted in its present form. The authors of the present article have to correct the issues.

Author Response

Dear editor,

Thank you for your message. The manuscript was revised according to your advice. I made some additional changes and marked those changes with red color in revised manuscript. I am looking forward to your reply.

 

 

With best wishes,

 

Yanfei PAN Ph.D.

College of Materials Science and Art Design

Inner Mongolia Agricultural University

Hohhot, 010018

P.R. China

Author Response File: Author Response.pdf

Reviewer 4 Report

The experiments carried out by the authors seem to be seemingly clear. However, there is a space for justification of their approach:

·    The authors chose Ni/poplar/Ni composite for their experiments. However, nowhere is explained why this combination, according to which criteria it was selected in this combination. Without justification it could be chosen other combination next time and the whole process carried out again with other entry materials.

·    The data indicated by the devices up to many decimal figures do not represent the real values if the experiments should be repeated. The experiments were carried out at least in triplicate or only one experiment was carried out?

·    The accuracy of the introduced numbers (Figs. 5-7, Table 1 and throughout the text should be reconsidered and more real values should be used (l. 341, etc.)

·    For better legibility of the Introduction a 4-column table with the authors, used material, density, and EMI SE summarizing the preceding text could help very much.

Conclusion: The authors should specify why the used materials were chosen, whether the experiments were repeated, and also usage of more responsible and representative experimental numbers should be introduced.

Author Response

Dear editor,

Thank you for your message. The manuscript was revised according to your advice. I made some additional changes and marked those changes with red color in revised manuscript. I am looking forward to your reply.

 

 

With best wishes,

 

Yanfei PAN Ph.D.

College of Materials Science and Art Design

Inner Mongolia Agricultural University

Hohhot, 010018

P.R. China

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript has been revised according to the Reviewers' comments and suggestions; therefore, it is now suitable for publication in Coatings journal

Author Response

Dear editor,

Thank you for your message. I am looking forward to your reply.

 

 

With best wishes,

 

Yanfei PAN Ph.D.

College of Materials Science and Art Design

Inner Mongolia Agricultural University

Hohhot, 010018

P.R. China

 

Author Response File: Author Response.pdf

Reviewer 3 Report

SUMMARY

The authors deal with issues related to electromagnetic pollution and the possibilities of eliminating electromagnetic radiation using suitable shielding material. The authors produced a light and thin nickel-wood-nickel composite material for electromagnetic interference shielding. For the production of composite shielding material, the authors used a simple electroless plating method while applying a layer of nickel on both sides of natural wood as a substrate. The authors experimented with the time of applying the Ni layer to the wood and the number of layers deposited on the wood surface. The authors characterized the electro-physical properties of the Ni-wood-Ni composite material by measuring electrical conductivity, scanning electron microscopy, hydrophobicity and S-parameters. In conclusion, the authors state that the shielding efficiency of the Ni-wood-Ni composite material is 94.1 dB, while the shielding efficiency by absorption dominates.

POSITIVE ASPECTS

1. Based on a literature review, the authors point to the issue of EMI environmental pollution.
2. Based on a literature review, the authors present the various techniques and materials used to prepare EMI shielding.
3. The authors prepared a sandwich-structured EMI shielding material made of nickel-plated porous wood using the electroless plating method and examined its electro-physical properties.

ISSUES

The presented work is useful but has some issues that need to be removed. I have a few comments that can be used to improve the article.

Minor issues
1. According to the ISO guidelines, no spaces should be used after plus, minus, or plus-or-minus signs that designate positive or negative values, e.g., 0.35 ±0.01 mm and not 0.35 ± 0.01 mm (line 112).

RECOMMENDATIONS

1. In Figure 9, the authors present the SE_T, SE_R, and SE_A shielding efficiencies. According to the mentioned frequency dependences of the SE components, it can be concluded that formula (4) is not valid. For example, from Figure 9k for five minutes, the values SE_T = 53.1 dB, SE_A = 34.61 dB and SE_R = 0.16 dB can be found. However, in Figure 9e-g, the SE_A values are negative. The average of all negative SE_A values should also be negative. It is better to report the SE_A values in decibels in Figure 9e-g as positive.

CONCLUSION

I find this article helpful. Regretfully, the paper cannot be accepted in its present form. The authors of the present article have to correct the issues.

Author Response

Dear editor,

Thank you for your message. The manuscript was revised according to your advice. I made some additional changes and marked those changes with red color in revised manuscript. I am looking forward to your reply.

 

 

With best wishes,

 

Yanfei PAN Ph.D.

College of Materials Science and Art Design

Inner Mongolia Agricultural University

Hohhot, 010018

P.R. China

Author Response File: Author Response.pdf

Reviewer 4 Report

The authors apparently improved their preceding manuscript in many aspects.

However, one question still persists: are the authors able to justify an accuracy of Sa up to 1 nm? If not the corresponding values in Tables 3-5 should be adequately rounded off.

For better orientation in the results comparing 1, 2 and 3 depositions of Ni, the Tables should be condensed to the only one giving a possibility to present a comparison in more user-friendly form.

For instance the following table could be used:

 

                                   Area 1 Area 2 Area 3 Area 4 Area 5 Mean value

1 min                          

1 deposition Ni           xx.xx   yy.yy   etc.

2 depositions Ni

3 depostitions Ni

 

5 mins                        

1 deposition Ni           xx.xx   yy.yy   etc.

2 depositions Ni

3 depostitions Ni

 

10 mins                                  

1 deposition Ni           xx.xx   yy.yy   etc.

2 depositions Ni

3 depostitions Ni

 

15 miss                                   

1 deposition Ni           xx.xx   yy.yy   etc.

2 depositions Ni

3 depostitions Ni

 

20 mins                                  

1 deposition Ni           xx.xx   yy.yy   etc.

2 depositions Ni

3 depostitions Ni

 

25 mins                                  

1 deposition Ni           xx.xx   yy.yy   etc.

2 depositions Ni

3 depostitions Ni

 

Author Response

Dear editor,

Thank you for your message. The manuscript was revised according to your advice. I made some additional changes and marked those changes with red color in revised manuscript. I am looking forward to your reply.

 

 

With best wishes,

 

Yanfei PAN Ph.D.

College of Materials Science and Art Design

Inner Mongolia Agricultural University

Hohhot, 010018

P.R. China

Author Response File: Author Response.pdf