Low-Cost Multifunctional Vacuum Chamber for Manufacturing PDMS Based Composites

Round 1

Reviewer 1 Report

Dear authors,

Thank you for your manuscript. Unfortunately, no methods to characterize the samples were presented. Please explain in detail why you did not use characterisation methods. Apart from dispersion, what other methods do you plan to use for characterisation of the fabricated samples?

Author Response

First, we would like to thank the reviewer for taking her/his precious time to read our manuscript and for providing thoughtful comments and suggestions. Note that changes made to this revised version of the manuscript are highlighted in yellow.

Thank you for your manuscript. Unfortunately, no methods to characterize the samples were presented. Please explain in detail why you did not use characterisation methods. Apart from dispersion, what other methods do you plan to use for characterisation of the fabricated samples?

We would like to thank the Reviewer for the attention paid to this research work. The main goal of this work is to present a new low-cost multifunctional vacuum chamber and show the advantages and disadvantages of this equipment when compared to conventional ones. Indeed, we have developed equipment that can control rotational speed, temperature, and vacuum by only 250€. We have proved and shown several advantages of this equipment to manufacture PDMS with beeswax composites and we have compared it with the traditional way of mixing these components. For this task, by means of an inverted microscope, we have done a qualitative evaluation by analyzing the distribution of a small amount of beeswax within the PDMS, by using samples obtained by both methods. In addition, it was added a quantitative evaluation by performing tensile and optical tests, which are presented in the revised version of the manuscript (please see pages 14 and 15). As described in the manuscript, the method using the proposed multifunctional vacuum chamber was more efficient when compared to the conventional method. Currently, we are performing additional tests with different percentages of beeswax within the PDMS. Hence, we are carrying out mechanical (tensile and hardness), optical (spectrophotometric), wettability, DMA, and TGA tests, and we expected to publish these results in the near future.

Please note that new data and graphs were added in the new revised manuscript. In addition, the English and also several figures were improved.

Reviewer 2 Report

This paper describes multifunctional vacuum chamber development for PDMS based composites. The topic of this review would be interesting to the readers.
However, some of my concerns are:
  
1. I believe the reason why authors chose the beeswax was not well emphasized in the text. This may be partly because there is no clear application shown in the paper, but I believe the introduction part can also be improved. 

2. What is the target application. It would be good to evaluate with application how this proposal improves the performance etc. compared with traditional approach. 
For example, Shi, Yingli, et al. "Temperature-dependent thermal and mechanical properties of flexible functional PDMS/paraffin composites." Materials & Design 185 (2020): 108219. evaluated stress, strain etc. Making superhydrophoic surface is the one mentioned in the introduction, or if not limited to wax then some nanoparticles mixing can be used as applications and evaluations.  

3. Have you tried different concentration/type of materials (wax, nanoparticles.). 

4. I am wondering whether there are any other methods can be added e.g. image processing, EDX mapping etc. also work for uniformity analysis in addition to microscope image.

5. Line433: "It is concluded from the electron 433 microscope images that the samples manufactured using the multifunctional vacuum 434 chamber show greater uniformity of beeswax in the PDMS. 435". Did authors use the electron microscope or an optical microscope. 

Overall, there is no doubt the paper is useful to the researchers. However, the scientific novelty was not well emphasized. Also, the paper lacks quantitative analysis. There are no graphs to support how this work will be useful in real applications. Unless there is supplemental information, at this moment, despite the massive effort and great topics, the paper needs more works, improvements and I would suggest additional experiments.  

Author Response

We would like to acknowledge the reviewer for spending his/her valuable time reading our manuscript and for presenting important comments and suggestions. Please note that the changes made in this revised version of the manuscript are highlighted in yellow

This paper describes multifunctional vacuum chamber development for PDMS based composites. The topic of this review would be interesting to the readers. However, some of my concerns are:

1. I believe the reason why authors chose the beeswax was not well emphasized in the text. This may be partly because there is no clear application shown in the paper, but I believe the introduction part can also be improved. 

We would like to thank the Reviewer for the recommendation that we completely agree with. In this way, we have clarified and emphasized the role of the beeswax when is mixed with PDMS and, in this way, we have improved the introduction part where we have added additional information about this subject.

2. What is the target application. It would be good to evaluate with application how this proposal improves the performance etc. compared with traditional approach. For example, Shi, Yingli, et al. "Temperature-dependent thermal and mechanical properties of flexible functional PDMS/paraffin composites." Materials & Design 185 (2020): 108219. evaluated stress, strain etc. Making superhydrophoic surface is the one mentioned in the introduction, or if not limited to wax then some nanoparticles mixing can be used as applications and evaluations.  

Thank you very much for your observation. The main goal of this work is to present a new low-cost multifunctional vacuum chamber and show the advantages and disadvantages of this equipment when compared to conventional ones. We have proved and shown several advantages of this equipment to manufacture PDMS with beeswax composites and we have compared it with the traditional way of mixing these components. For this task, by means of an inverted microscope, we have done a qualitative evaluation by analyzing the distribution of a small amount of beeswax within the PDMS, by using samples obtained by both methods. In addition, it was added a quantitative evaluation by performing tensile and optical tests, which are presented in the revised version of the manuscript (please see pages 14 and 15). As described in the manuscript, the method using the proposed multifunctional vacuum chamber was more efficient when compared to the conventional method.

In this work, we have focused on mixing small amounts of beeswax to improve the hydrophobicity of the PDMS surface. However, we are aware that is possible to have a similar effect using nanoparticles like polydimethylsiloxane/silica nanocomposite. We have improved the introduction part where we have included this information.

3. Have you tried different concentration/type of materials (wax, nanoparticles.). 

We have carried out in another research work [1] the use of materials such as paraffin, using the conventional method of manufacturing the specimens, and we have found that it will be very important to develop a process that allows better control of some parameters like temperatures, rotational speed, and vacuum level, so, we had the idea to manufacture the equipment presented in this work. Currently, we are performing additional tests with different percentages of beeswax within the PDMS. Hence, we are carrying out mechanical (tensile and hardness), optical (spectrophotometric), wettability, DMA, and TGA tests, and we expected to publish these results in the near future.

[1] Sales F, Souza A, Ariati R, et al. (2021) Composite Material of PDMS with Interchangeable Transmittance: Study of Optical, Mechanical Properties and Wettability. J Compos Sci 5: 110.

4. I am wondering whether there are any other methods can be added e.g. image processing, EDX mapping etc. also work for uniformity analysis in addition to microscope image.

I would like to thank the reviewer for the recommendations, and we have added a quantitative evaluation by performing tensile and optical tests, which are presented in the revised version of the manuscript (please see pages 14 and 15). We would like in the future to perform analysis using an EDX mapping, but unfortunately at the moment, we do not have access to such expensive equipment.

5. Line433: "It is concluded from the electron 433 microscope images that the samples manufactured using the multifunctional vacuum 434 chamber show greater uniformity of beeswax in the PDMS. 435". Did authors use the electron microscope or an optical microscope. 

We would like to apologize for the misunderstanding. In this work, we have used an optical microscope. We have corrected this part in the revised manuscript (please see lines 472-473 and Figure 11).

Overall, there is no doubt the paper is useful to the researchers. However, the scientific novelty was not well emphasized. Also, the paper lacks quantitative analysis. There are no graphs to support how this work will be useful in real applications. Unless there is supplemental information, at this moment, despite the massive effort and great topics, the paper needs more works, improvements and I would suggest additional experiments.

Please note that it was added a quantitative evaluation by performing tensile and optical tests, which are presented in the revised version of the manuscript (please see pages 14 and 15). As a result, new data and graphs were added in the newly revised manuscript. Additionally, the English and also several figures were improved.

 

Reviewer 3 Report

The article is a very poor subject and written at a middle level.

The work is purely engineering, in my personal humble opinion, the work duplicates the already known engineering solutions for automating the creation of products from composites and epoxy materials. In general, it looks like a student's master's thesis without scientific novelty. There are no graphs of the transition process of formation of the required composition of the composite, which could bring novelty to this work. Based on these statements, I recommend rejecting this article.

Author Response

The article is a very poor subject and written at a middle level.

The work is purely engineering, in my personal humble opinion, the work duplicates the already known engineering solutions for automating the creation of products from composites and epoxy materials. In general, it looks like a student's master's thesis without scientific novelty. There are no graphs of the transition process of formation of the required composition of the composite, which could bring novelty to this work. Based on these statements, I recommend rejecting this article.

First, we would like to thank the reviewer for taking the time to read our manuscript and for providing thoughtful comments and suggestions. Note that changes made to this revised version of the manuscript are highlighted in yellow.

The main goal of this work is to present a new low-cost multifunctional vacuum chamber and show the advantages and disadvantages of this equipment when compared to conventional ones. Indeed, we have developed equipment that can control rotational speed, temperature, and vacuum by only 250€. We have proved and shown several advantages of this equipment to manufacture PDMS with beeswax composites and we have compared it with the traditional way of mixing these components. For this task, by means of an inverted microscope, we have done a qualitative evaluation by analyzing the distribution of a small amount of beeswax within the PDMS, by using samples obtained by both methods. In addition, it was added a quantitative evaluation by performing tensile and optical tests, which are presented in the revised version of the manuscript (please see pages 14 and 15). As described in the manuscript, the method using the proposed multifunctional vacuum chamber was more efficient when compared to the conventional method. Currently, we are performing additional tests with different percentages of beeswax within the PDMS. Hence, we are carrying out mechanical (tensile and hardness), optical (spectrophotometric), wettability, DMA, and TGA tests, and we expected to publish these results in the near future.

Please note that new data and graphs were added to the newly revised manuscript. In addition, the English and also several figures were improved.

 

Round 2

Reviewer 2 Report

Authors responded all my comments. The manuscript was greatly improved. Though, I think it would be better to explain the Fig.12 and Fig.13 in details. e.g. In Fig.12, 13, I believe dots are the measured data. What are the shades and lines: theoretical equation, trend lines or error bars?  In Fig. 13, typo in x axis. Also, could you please elucidate how authors evaluated transparency (e.g. 9%) in the text.

Author Response

First, we would like to thank the reviewer for taking the time to read our manuscript and for providing comments and suggestions. Note that changes made to this revised version of the manuscript are highlighted in yellow.

 

The authors responded to all my comments. The manuscript was greatly improved. Though, I think it would be better to explain Fig.12 and Fig.13 in detail. e.g. In Fig.12, 13, I believe dots are the measured data. What are the shades and lines: theoretical equation, trend lines or error bars? In Fig. 13, typo in x axis. Also, could you please elucidate how authors evaluated transparency (e.g. 9%) in the text?

We are very grateful that the reviewer has accepted our previous justifications and changes to the manuscript.

Thank you very much for the opportunity to explain the details of Figure 12. The red dots help to distinguish the curves, the line is the arithmetic mean and the shadows are the standard deviation of the respective curves. Regarding Figure 13, we really appreciate your comment and we have corrected the mistake in the new version. The difference in optical transmittance between the specimens made by MVC and by the traditional way is 9%, that is, the specimens made by MVC are 9% more transparent than the specimens made by the traditional way. All the details referred to in this justification are highlighted (yellow) in the manuscript.

Reviewer 3 Report

The authors of the article took into account many comments, but they added results that are little described. First of all, the authors provide data on stress analysis. However, do not describe the setting of the experimental sample, the parameters, and the accuracy of measurement of all data, etc. The following parameters must be provided for each of the described tests and results. This will allow the reader to understand the adequacy of the results and assess their accuracy.
In particular, the authors conclude that "When it comes to the maximum strain of samples manufactured in the MVC, there was an improvement of more than 65% when compared to samples manufactured by the conventional method." However, the article has no data and no references to confirm this.

Author Response

First, we would like to thank the reviewer for taking the time to read our manuscript and for providing comments and suggestions. Note that changes made to this revised version of the manuscript are highlighted in yellow.

 

The authors of the article took into account many comments, but they added results that are little described. First of all, the authors provide data on stress analysis. However, do not describe the setting of the experimental sample, the parameters, and the accuracy of measurement of all data, etc. The following parameters must be provided for each of the described tests and results. This will allow the reader to understand the adequacy of the results and assess their accuracy.

Thank you very much for the opportunity to explain more details about the experimental tensile test: tensile tests were performed for 5 different specimens of each sample in a universal testing machine (Shimadzu, model Autograpf AGS-X), using a cell-load of 10 kN with accuracy within ±1% indicated test force (at 1/500 to 1/1 load cell rating) and the tensile tests were accomplished by means of a displacement control. To carry out the test, a pre-test was mounted on the machine, with a velocity of 5 mm/min, being adjusted until it reached a preload of 1 N and, from this point, the test was set up for a velocity of 500 mm/min until it breaks. To prevent the slip of the samples during the test, fine sandpaper was placed at the ends of the samples. The samples were fabricated, and the test was performed in accordance with ASTM D412. Figure 12 presents the results of the measurements: the lines (red and black) are the arithmetic mean and the shadows are the standard deviation of the respective curves. All these changes are written in the manuscript and highlighted in yellow.

 

In particular, the authors conclude that "When it comes to the maximum strain of samples manufactured in the MVC, there was an improvement of more than 65% when compared to samples manufactured by the conventional method." However, the article has no data and no references to confirm this.

Thank you very much for the opportunity to better explain the improvement of the mechanical properties of the specimens made by the MVC. The arithmetic average of the tensile strength of samples manufactured by the conventional method (CM) is approximately 2.36 MPa (please, see Figure 12), which is consistent with the studies reported in the literature [A]. As for the MVC samples the tensile strength corresponds to 3.27 MPa (please, see Figure 12). As a result, there was an improvement in maximum tensile strength and maximum strain. The maximum tensile strength of samples manufactured with the MVC has improved about 39% when compared with the samples manufactured by the CM. When it comes to the maximum strain of the samples, the results were 0.48 and 0.81 (please, see Figure 12) for the samples manufactured by the conventional method and manufactured in the MVC, respectively, being the first value (0.48) consistent with the literature [A]. Hence, these results show that there was an improvement bigger than 65% when compared with the samples manufactured using MVC and manufactured with the CM. All these changes were added to the manuscript and highlighted in yellow.

 

[A] Ariati R, Sales F, Souza A, et al. (2021) Polydimethylsiloxane Composites Characterization and Its Applications: A Review. Polymers (Basel) 13: 4258.

 

Round 3

Reviewer 3 Report

The authors improved the description of the experimental setup and the obtained results. So the article now looks better.