Optimization of Chitin Nanofiber Preparation by Ball Milling as Filler for Composite Resin

Round 1

Reviewer 1 Report

-Add a graphics or image or layout showing the infos of making Chitin nanofiber.

-This reviewer wants to see a comparison table or statements on the findings of chitin nanofibers to some other type of fibers (which are commonly used).

-In this study, the optimal conditions were determined as ball size of 1 mm, a total ball weight of 300 g, and a milling time of 150 minutes. However, this is a pure experimental study. Explain the details of your optimization steps.

-The most efficient crushing is held at 1mm diameter. Explain the depth of this process.

-SEM and AFM were not defined. Write them out and explain.

-Adding a table in the Materials and Methods section will be good to show all pieces here.

-For Figures 5 and 9, Add a legend. What is blue dot? What is brown dot?

-In conclusion, re-write the following sentence. It is still unclear. Make it in two separate sentences.

That is, the morphology of the nanofibers and the viscosity and transparency of their dispersions and the yield of the nanofibers, and the transparency and viscosity of their cast films changed significantly depending on these milling conditions.

Author Response

Dear Reviewer #1:

Thank you very much for your helpful comments. We carefully considered reviewers’ comments and corrected. Thanks to the reviewers' qualified advice, the revised version is better for readers. We believe that the revised manuscript is acceptable to the Journal of Composites Science.

Reviewer #1:

1. Add a graphics or image or layout showing the infos of making chitin nanofiber.

An image on the preparation of chitin nanofibers is included in the Graphical Abstract.

2. This reviewer wants to see a comparison table or statements on the findings of chitin nanofibers to some other type of fibers (which are commonly used).

Cellulose nanofibers were introduced in the text as a material related to chitin nanofibers (Line 43-46). In addition, we introduced the previous production method of chitin nanofibers and described the progress of the new method compared to the previous method (Line 62-65). Furthermore, the advantages of using a ball mill as a milling machine are shown (Line 70-72).

3. In this study, the optimal conditions were determined as ball size of 1 mm, a total ball weight of 300 g, and a milling time of 150 minutes. However, this is a pure experimental study. Explain the details of your optimization steps.

Different milling conditions were used to study the effect of these factors, including ball size (0.3-20 mm), total ball weight (20-600 g), and milling time (30-300 min) (Line 69-92). A series of manufacturing conditions conducted using ball mill is described in Supporting Information (Table s1, s2 and s3).

4. The most efficient crushing is held at 1mm diameter. Explain the depth of this process.

The reasons why the maximum chitin grinding efficiency is reached when the ball diameter is 1 mm are described in more detail (Line 139-144).

5. SEM and AFM were not defined. Write them out and explain.

SEM and AFM images of chitin ground under various conditions have been added to Supporting Information (Figure s1-s6).

6. Adding a table in the Materials and Methods section will be good to show all pieces here.

The conditions for grinding chitin by ball milling are tabulated in the Supporting Information (Table s1-s3).

7. For Figures 5 and 9, Add a legend. What is blue dot? What is brown dot?

What each dot represents in Figure 2, 5 and 9 are noted in the figure captions.

8. In conclusion, re-write the following sentence. It is still unclear. Make it in two separate sentences. That is, the morphology of the nanofibers and the viscosity and transparency of their dispersions and the yield of the nanofibers, and the transparency and viscosity of their cast films changed significantly depending on these milling conditions.

We divided the Conclusion into two sentences to make them clearer as follows.

That is, the morphology of the nanofibers and the viscosity and transparency of their dispersions and the yield of the nanofibers changed by them. And the transparency and viscosity of their cast films also changed significantly depending on these milling conditions.

Reviewer 2 Report

·         The overall paper lacks any novel findings or enrichment of existing field of knowledge in the area of mechanical engineering. In general, the authors report on observations  but provide little evidence or explanations that provide insight and understanding of the results. The reviewer has a concern regarding the novelty of this paper. The authors should clarify the difference between the submitted paper and the following published paper (see for examples (Zewude, D. A., Izawa, H., & Ifuku, S. (2021). Optimum Preparation Conditions for Highly Individualized Chitin Nanofibers Using Ultrasonic Generator. Polymers, 13(15), 2501). And (Zewude, D. A., Noguchi, T., Sato, K., Izawa, H., & Ifuku, S. (2022). Production of chitin nanoparticles by bottom-up approach from alkaline chitin solution. International Journal of Biological Macromolecules, 210, 123-127)

·         Can you justify the advantages of ball milling compared to ultrasonic technique ?  

·         In the introduction, for similar work, more references are recommended to add in the revised version:

ü  El Moumen, A., Tarfaoui, M., Nachtane, M., & Lafdi, K. (2019). Carbon nanotubes as a player to improve mechanical shock wave absorption. Composites Part B: Engineering, 164, 67-71.

ü  Tarfaoui, M., El Moumen, A., Lafdi, K., Hassoon, O. H., & Nachtane, M. (2018). Inter laminar failure behavior in laminate carbon nanotubes-based polymer composites. Journal of Composite Materials, 52(26), 3655-3667.

·         The last paragraph of the introduction should be really improved. Indeed, the authors must rephrase this part in terms of experimental findings and to emphasis the paper’s structuration.

·         There are so many syntax errors, which should be tidied before acceptance. By the way, the quality of some figures should be improved.

·         The work is a good report of experiment investigations, but which are the lessons learnt? The authors have to clarify this otherwise the paper cannot be accepted.

Author Response

Dear Reviewer #2:

Thank you very much for your helpful comments. We carefully considered reviewers’ comments and corrected. Thanks to the reviewers' qualified advice, the revised version is better for readers.We believe that the revised manuscript is acceptable to the Journal of Composites Science.

1. The overall paper lacks any novel findings or enrichment of existing field of knowledge in the area of mechanical engineering. In general, the authors report on observations but provide little evidence or explanations that provide insight and understanding of the results. The reviewer has a concern regarding the novelty of this paper. The authors should clarify the difference between the submitted paper and the following published paper (see for examples (Zewude, D. A., Izawa, H., &Ifuku, S. (2021). Optimum Preparation Conditions for Highly Individualized Chitin Nanofibers Using Ultrasonic Generator. Polymers, 13(15), 2501). And (Zewude, D. A., Noguchi, T., Sato, K., Izawa, H., & Ifuku, S. (2022). Production of chitin nanoparticles by bottom-up approach from alkaline chitin solution. International Journal of Biological Macromolecules,210, 123-127)

The advantages of using a ball mill compared to other mills are described in line 70-72. In addition, the differences from previous papers noted by the reviewers were described in line 62-65. We also cited those papers with Ref. No. 23 and 24.

2. Can you justify the advantages of ball milling compared to ultrasonic technique?

The advantages of using a ball mill as a grinder over ultrasonic technique are shown in line 70-72.

3. In the introduction, for similar work, more references are recommended to add in the revised version: El Moumen, A., Tarfaoui, M., Nachtane, M., & Lafdi, K. (2019). Carbon nanotubes as a player to improve mechanical shockwave absorption. Composites Part B: Engineering, 164, 67-71. Tarfaoui, M., El Moumen, A., Lafdi, K., Hassoon, O. H., &Nachtane, M. (2018). Inter laminar failure behavior in laminate carbon nanotubes-based polymer composites. Journal of Composite Materials, 52(26), 3655-3667.

According to the reviewer's instructions, we cited two papers on carbon nanotubes as previous leading studies (Line 41-43, Ref. No. 12 and 13).

4. The last paragraph of the introduction should be really improved. Indeed, the authors must rephrase this part in terms of experimental findings and to emphasis the paper’s structuration.

According to the reviewer's instructions, the last paragraph of the Introduction has been revised (Line 75-79). I have divided the last sentence into two to avoid obscure expressions.

5. There are so many syntax errors, which should be tidied before acceptance. By the way, the quality of some figures should be improved.

The entire sentence was carefully reviewed, and each syntax errors were appropriately corrected. Figures have been edited by the editor to a lower resolution to reduce the file size. The figures in the published version should appear in higher resolution.

6. The work is a good report of experiment investigations, but which are the lessons learnt? The authors have to clarify this otherwise the paper cannot be accepted.

The lessons we learnt were as follows. They are included in Conclusion (Line 327-335):

Optimal conditions for producing chitin using a ball mill were identified. We found that ball size, total ball weight, and milling time significantly impact chitin milling efficiency. Because of its excellent physical properties, chitin nanofiber is expected to be used as a reinforcing material to create nanocomposites. Technology for efficiently grinding chitin into nanofibers using less energy is essential to promote the use of chitin nanofibers produced from underutilized resources.

Round 2

Reviewer 1 Report

The authors answered the concerns clearly. The paper could be published now.

Reviewer 2 Report

the authors answered my questions and therefore I am in favor of the publication of this article.