Preparation and Acoustic Performance of Porous Aerogel Composites of Graphene Oxide and Cellulose

Round 1

Reviewer 1 Report

This manuscript “Preparation and acoustic performance of porous aerogel composites of graphene oxide and cellulose” deals with the preparation of CEL-GO composite aerogels by freeze-drying technique. Although extensive work has been performed, several points must be improved before acceptance of this manuscript.

1)      Full names should appear in the text earlier than abbreviated ones. For example, in the "Abstract" section the transcript of all the methods should be presented, and also first write the full names of cellulose and graphene oxide, and then shorten it to CEL and GO.

2)      What is "JTZB"? There is no decoding in the text of the manuscript.

3)      In the introduction, it is necessary to describe in more detail about GO as modifier.

4)      What other modifiers are used for aerogels? What materials, besides cellulose, are used to make aerogels with such properties? This information should be reflected in the introduction.

5)      The novelty of this research is needed in the last paragraph of the introduction.

6)      The "2.1. Materials Preparation of CEL-GO composite aerogels" section should include manufacturers and characteristics of the materials used, for example, manufacturer and molecular weight for cellulose, etc.

7)      Why was a crosslinker used for aerogels?

8)      The "2.1. Materials Preparation of CEL-GO composite aerogels" section contains the names of membranes corresponding to different ratios of CEL and GO. These names (CG-1, CG-2, CG-3 and CG-4) should be used further in the figures and captions to the figures.

9)      In Figure 1, what composition of the CEL-GO composite was studied? This should be indicated in the text and in the figure.

10)  In Figures 5 and 6, the quality of the drawings should be improved.

11)  The "Conclusions" section should reflect all the results obtained in the study.

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

Major revision taking into account the response point by point for the following:

Reviewer #1:

1. Full names should appear in the text earlier than abbreviated ones. For example, in the "Abstract" section the transcript of all the methods should be presented, and also first write the full names of cellulose and graphene oxide, and then shorten it to CEL and GO.

Thanks a lot for your advice. Based on your advice, the above problems has been corrected and marked red in the manuscript.

2. What is "JTZB"? There is no decoding in the text of the manuscript.

Thanks a lot for your advice. JTZB means that the Standing Wave Tube Test System is equipped with JTSOFT-ZB professional software, which simultaneously acquires and displays sound pressure signals, automatically generates sound absorption coefficients and draws sound absorption curves. And the above problem has been corrected and marked red in the manuscript.

3. In the introduction, it is necessary to describe in more detail about GO as modifier.

Thanks a lot for your advice. Based on your advice, the above problems has been corrected and marked red in the manuscript.

4. What other modifiers are used for aerogels? What materials, besides cellulose, are used to make aerogels with such properties? This information should be reflected in the introduction.

Thanks a lot for your advice. Based on your advice, the above problems has been corrected and marked red in the manuscript.

5. The novelty of this research is needed in the last paragraph of the introduction.

Thanks a lot for your advice. Based on your advice, the above problems has been corrected and marked red in the manuscript.

6. The "2.1. Materials Preparation of CEL-GO composite aerogels" section should include manufacturers and characteristics of the materials used, for example, manufacturer and molecular weight for cellulose, etc.

Thanks a lot for your advice. Based on your advice, the above problems has been corrected and marked red in the manuscript.

7. Why was a crosslinker used for aerogels?

Thanks a lot for your advice. Cross-linker because it has more active groups can be combined with the hydroxyl group on the cellulose to form hydrogen bonds, or with other components of the material to form other chemical bonds, thereby increasing the density of the gel material and the degree of cross-linking is greatly enhanced, the macro-expression of the mechanical properties of the material, the stability of the material has been greatly improved, thus cross-linker has a wide range of applications in the preparation of gel material.

8. The "2.1. Materials Preparation of CEL-GO composite aerogels" section contains the names of membranes corresponding to different ratios of CEL and GO. These names (CG-1, CG-2, CG-3 and CG-4) should be used further in the figures and captions to the figures.

Thanks a lot for your advice. Based on your advice, the above problems has been corrected and marked red in the manuscript.

9. In Figure 1, what composition of the CEL-GO composite was studied? This should be indicated in the text and in the figure.

Thanks a lot for your advice.

Figure 1 shows the X-ray diffraction pattern of a material. Different materials have different crystals, resulting in different levels of diffraction and absorption of X-rays, which ultimately result in different characteristic peak patterns that can be used to analyse the corresponding components contained in the material. For example, the characteristic peaks of cellulose type I and graphene oxide, as well as the characteristic peaks of the combination of the two to form a new chemical bond, appear in this figure, indicating that the composite material produced does not introduce other impurities and reflects the combination of the two component materials.

The above problem has been corrected and marked red in the manuscript.

10. In Figures 5 and 6, the quality of the drawings should be improved.

Thanks a lot for your advice. Based on your advice, the above problems has been corrected and marked red in the manuscript.

11. The "Conclusions" section should reflect all the results obtained in the study.

Thanks a lot for your advice. Based on your advice, the above problems has been corrected and marked red in the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript deals with the preparation of cellulose aerogel and cellulose aerogel reinforced by GO for sound absorption purpose. The prepared materials have been characterized, chemically (FT-IR and Raman), structurally (XRD) and morphologically (SEM); in addition, porosity and adsorption properties have been measured by BET, and JTZB tests have been used to assess sound absorption capability.

The manuscript is quite interesting, however some improvements are required before its publication:

- Many studies on cellulose aerogels composites for sonacoustic absorption are available in the literature. Cellulose aerogels have been filled with silica, ZnO, etc. but these studies are not cited in the manuscript Introduction Section. Such section of the manuscript could be much improved by including this literature.

- The aim of this work needs to be clarified: what are the advantages of using GO as filler for cellulose aerogels compared to other fillers? Does GO improve mechanical properties, pore size, porosity content, or what else related to sonoacoustic absorption? Such considerations should be given in the revised manuscript version.

- Authors have used a quite standard testing method for measuring the acoustic absorption performance; however, some details about should be provided in the Experimental Section (at least, model and manufacturer name of the JTZB standing wave tube).

- Some information about the mechanical properties of the obtained cellulose aerogel and cellulose aerogel reinforced by GO could represent a very useful information for readers. I suggest, for example, a simple stress-strain curve for both material types.

- The following sentence (line 232): “and its layered porous structure is used to increase the acoustic wave transmission path” should be better clarified. Why GO is capable to increase the transmission path? Does GO increase porosity in the aerogel? If yes, why?

English language requires only a minor editing.

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

Major revision taking into account the response point by point for the following:

Reviewer #2:

1. Many studies on cellulose aerogels composites for sonacoustic absorption are available in the literature. Cellulose aerogels have been filled with silica, ZnO, etc. but these studies are not cited in the manuscript Introduction Section. Such section of the manuscript could be much improved by including this literature.

Thanks a lot for your advice. Based on your advice, the above problems has been corrected and marked red in the manuscript.

2. The aim of this work needs to be clarified: what are the advantages of using GO as filler for cellulose aerogels compared to other fillers? Does GO improve mechanical properties, pore size, porosity content, or what else related to sonoacoustic absorption? Such considerations should be given in the revised manuscript version.

Thanks a lot for your advice. Graphene oxide has a honeycomb two-dimensional planar structure, which is entangled or wrapped with cellulose molecular chains, which in turn causes the cavity wall structure of the cellulose gel to be closed, semi-closed or long-range, thus improving the material's ability to consume acoustic waves and achieving better sound absorption.

3. Authors have used a quite standard testing method for measuring the acoustic absorption performance; however, some details about should be provided in the Experimental Section (at least, model and manufacturer name of the JTZB standing wave tube).

Thanks a lot for your advice. Based on your advice, the above problems has been corrected and marked red in the manuscript.

4. Some information about the mechanical properties of the obtained cellulose aerogel and cellulose aerogel reinforced by GO could represent a very useful information for readers. I suggest, for example, a simple stress-strain curve for both material types.

Thanks a lot for your advice. Graphene oxide to improve the mechanical properties of composite materials is very meaningful, but the focus of this study is to explore the composite mode of the two materials, and then analyse the impact on the acoustic performance of the material, so more experimental investigation and testing will be focused on the qualitative analysis of the material composition, the qualitative analysis of chemical bonding, the characterisation of the microstructure and the construction of the model. The mechanical properties and applications of materials with high acoustic properties are then analysed and tested accordingly.

5. The following sentence (line 232): “and its layered porous structure is used to increase the acoustic wave transmission path” should be better clarified. Why GO is capable to increase the transmission path? Does GO increase porosity in the aerogel? If yes, why?

Thanks a lot for your advice. Due to the two-dimensional layered structure of graphene oxide and the combination of entanglement and encapsulation with cellulose molecular chains, the pore structure of the cellulose gel will be changed, taking graphene as a reference, the same layer may have closed, semi-closed or long-range through holes. For closed and semi-closed pore structures, the acoustic wave loses most of its energy in the pore, for long-range through holes, in addition to consuming energy in the pore structure, the sound waves may also pass through the pores to contact the layered graphene structure in the next layer, and this sandwich construction makes the sound waves eventually repeat the loss process in the previous layer, from this perspective, the introduction of graphene increases the path of acoustic transmission and consumption, and also makes the material have a very high acoustic absorption coefficient.

Author Response File: Author Response.pdf