Microstructure Evaluation and Thermal–Mechanical Properties of ABS Matrix Composite Filament Reinforced with Multi-Walled Carbon Nanotubes by a Single Screw Extruder for FDM 3D Printing

Round 1

Reviewer 1 Report

The manuscript entitled “Microstructure evaluation and thermal-mechanical properties of ABS matrix composite filament reinforced with multi-walled carbon nanotubes by a single screw extruder in FDM 3D printing” was reviewed. The paper adds interesting material to the body of MEX and looks good.

 Please see my comments below in improving the quality of the paper: 

 

1. Authors are encouraged to proofread the paper
2. Add the scalebar to Figure 4.
3. Improve the quality of wording in Figure 3.
4. The scalebar in Figures 6&7 are not readable. Authors need to manually add the scalebars.
5. Conclusiongs need to be expanded with more detail on the finding of the paper.
6. Add a statement about the filament and producers.
7. Authors should read and add the following new and novel references from 2021:

Boğa, C., Investigation of mechanical and fracture behavior of pure and carbon fiber reinforced ABS samples processed by fused filament fabrication process.

Nathaphan, S. and W. Trutassanawin, Effects of process parameters on compressive property of FDM with ABS.

Parpala, R.C., D. Popescu, and C. Pupaza, Infill parameters influence over the natural frequencies of ABS specimens obtained by extrusion-based 3D printing.

Vyavahare, S. and S. Kumar, Numerical and experimental investigation of FDM fabricated re-entrant auxetic structures of ABS and PLA materials under compressive loading.

 Charalampous, P., I. Kostavelis, T. Kontodina, and D. Tzovaras, Learning-based error modeling in FDM 3D printing process.

Author Response

RESPONSE TO REVIEWER 1

Dear Editors and Reviewers,

Thank you for giving us the opportunity to submit a revised draft of our manuscript titled
“Microstructure evaluation and thermal–mechanical properties of ABS matrix composite filament reinforced with multi-walled carbon nanotubes by a single screw extruder for FDM 3D printing” to Journal of applied Sciences. We appreciate the time and effort that you and the reviewers have dedicated to providing your valuable feedback on our manuscript. We are grateful to the reviewers for their insightful comments on our manuscript. We have been able to incorporate changes to reflect most of the suggestions provided by the reviewers.

Here is a point-by-point response to the reviewers’ comments and concerns.

Point 1: Authors are encouraged to proofread the paper

Response 1: Yes, we have been revised the paper

 Point 2: Add the scalebar to Figure 6.

Response 2: Scalebar was added to figure 6

 Point 3: Improve the quality of wording in Figure 4.

Response 3: The wording in figure 4 have been clarified in manuscript

 Point 4: The scalebar in Figures 7&8 are not readable. Authors need to manually add the scalebars.

Response 4: Scalebars have been inserted in figure 7&8

 Point 5: Conclusions need to be expanded with more detail on the finding of the paper.

Response 5: The conclusions have been added more detail on the contributions of this study

 Point 6: Add a statement about the filament and producers.

Response 6: The fabricated 3D printing filament has a diameter of 1.75 ± 0.1 mm and it has been tested to ensure the same requirements as the printed filaments on the market.

 Point 7: Authors should read and add the following new and novel references from 2021:

Response 7: 5 references of 2021 year have been included in the references (19-23) and introduce in introduction section as comments by reviewers

In addition to the above comments, the regular edit checks the grammar, spelling, punctuation and phrasing have been corrected in revised manuscript (by English editing services of MPDI)

We look forward to hearing from you in due time regarding our submission and to respond to
any further questions and comments you may have.

Please see the attached a revised version of the manuscript..

Sincerely,

Le Thai Hung

Author Response File: Author Response.docx

Reviewer 2 Report

In the article entitled “Microstructure evaluation and thermal-mechanical properties of ABS matrix composite filament reinforced with multi-walled carbon nanotubes by a single screw extruder in FDM 3D printing”, the authors have discussed the fabrication and characterization of new printable ABS/MWCNTs composite filament for FDM process using extrusion technique. The following issues should be addressed before publication:

1. In the introduction section (lines 32 -33), the authors missed mentioning major 3D printing techniques like multi photon printing, SLM, DLP, etc.
2. Line 38 is rather superficial. The authors should consider clarifying more and highlight specific benefits and advantages.
3. Line 39-40: In short, anisotropic behavior.
4. Both the introduction and abstract should be amended to clearly state the novelty of the methods and sensitivity of the developed sensors.
5. Were the MWCNT fillers functionalized? How uniform dispersion was assured? Ununiform dispersion might lead to non-optimal properties observed in the printed composites. Please clarify.  
6. In lines 130-135 the authors have discussed the reinforcement of ABS substrate in light of the dispersion of MWCNT filler. There is no discussion on percolation threshold of MWCNT in ABS. Will percolation play a role in the mechanical properties of the printed product?
7. Lines 165-168: Please elaborate on the issues faced.
8. Lines 202-204: The authors have stated “However, it is believed that the dispersion of MWCNTs is not perfect with the higher MWCNTs content loading into the ABS matrix, they are aggregated and pulled out by the tensile stress as shown in Figures 7c-d”. Will this observation change with better dispersion of MWCNT?

It is desired that the manuscript is proofread thoroughly before publication. 

Comments for author File: Comments.docx

Author Response

RESPONSE TO REVIEWER 2

Dear Editors and Reviewers,

Thank you for giving us the opportunity to submit a revised draft of our manuscript titled “Microstructure evaluation and thermal–mechanical properties of ABS matrix composite filament reinforced with multi-walled carbon nanotubes by a single screw extruder for FDM 3D printing” to Journal of applied Sciences. We appreciate the time and effort that you and the reviewers have dedicated to providing your valuable feedback on our manuscript. We are grateful to the reviewers for their insightful comments on our manuscript. We have been able to incorporate changes to reflect most of the suggestions provided by the reviewers.

Here is a point-by-point response to the reviewers’ comments and concerns.

 

Point 1: In the introduction section (lines 32 -33), the authors missed mentioning major 3D printing techniques like multi photon printing, SLM, DLP, etc

Response 1: some other 3D printing techniques were mentioned in the introduction like MPL, SLM, DLP… in line 32-33. Has been revised (yellow highlighted)

Point 2: Line 38 is rather superficial. The authors should consider clarifying more and highlight specific benefits and advantages.

Response 2: The authors have been added more detail about the benefits and advantages of 3D printing: 3D printing offers many benefits over traditional processes, such as speed-to-market, lower costs, flexible design, print on demand and reduced waste. Has been revised (yellow highlighted)

Point 3: Line 39-40: In short, anisotropic behavior.

Response 3: Yes, we agree with your comments, and we have adjusted this sentence for clarity. Has been revised (yellow highlighted)

Point 4: Both the introduction and abstract should be amended to clearly state the novelty of the methods and sensitivity of the developed sensors.

Response 4: the modification has been done in manuscript

FDM 3D printing filament is widely used in the market, however, it is necessary to improve the strength and now there are also many methods of reinforcement mixing and extrusion to get the filament with better properties. However, there is no perfect method. Because it is necessary to improve the steps in the fabrication process to obtain filament with better properties.

Point 5: Were the MWCNT fillers functionalized? How uniform dispersion was assured? Ununiform dispersion might lead to non-optimal properties observed in the printed composites. Please clarify. 

Response 5: Yes, we agreed with your comments and updated the manuscript for the clarifying the problem. Has been revised (yellow highlighted) and added figure 1 on uniform dispersion of MWCNT functionalization.

The MWCNTs were chemical functionalized with carboxylic acid (-COOH) functional group at a temperature of 70 ^oC for 5 hours. After functionalization, MWCNT-COOH was dispersed into ethanol by a sonication process for 1h to prepare the MWCNTs suspension. This step was applied to deagglomerate and enhance the stability of uniform dispersion of purified MWCNTs (Figure 1). The functionalized MWCNTs can produce homogeneity uniform dispersion, strong interfacial bonds with polymers matrix, allowing CNT-based nanocomposites to possess high mechanical and functional properties. It is postulated that the functional groups attached on CNT affected the rheological behavior of polymer, which in turn facilitated a faster cure and wrapping of a protective polymer layer onto the CNT surface, preventing them from attracting one another.

Point 6: In lines 130-135 the authors have discussed the reinforcement of ABS substrate in light of the dispersion of MWCNT filler. There is no discussion on percolation threshold of MWCNT in ABS. Will percolation play a role in the mechanical properties of the printed product?

Response 6: Yes. Statistically, the percolation threshold should decrease with an increasing aspect ratio. However, the key is to have the MWCNTs as homogeneous as possible in the layer.  Reference “Low-Cost and Highly Sensitive Pressure Sensor with Mold-Printed Multi-Walled Carbon Nanotubes Dispersed in Polydimethylsiloxane”. Sensors 2021. We will study this problem in the next research.

Point 7: Lines 165-168: Please elaborate on the issues faced. “In practice, the low MFI value filament materials lead to many difficulties during the FDM feeding and extrusion processes; therefore, the high MWCNTs content composites are not favorable for commercial applications”

Response 7:

If the MWCNT content is high, the MFI coefficient will decrease, that making composite filament difficult to flow causing nozzle blockage, and the printing part is heterogeneous properties, effect on the bond strength between the reinforcement and the matrix. Moreover, in this study, MWCNT has a small density, so the large volume easily causes clumping, which can be observed in Figure 8c. In this study, a test print with a MWCNT content of 2%, the clumping phenomenon was small and insignificant compared to the injection head size, so it was selected as a research value.

Point 8: Lines 202-204: The authors have stated “However, it is believed that the dispersion of MWCNTs is not perfect with the higher MWCNTs content loading into the ABS matrix, they are aggregated and pulled out by the tensile stress as shown in Figures 7c-d”. Will this observation change with better dispersion of MWCNT?

Response 8: Generally, the performance of a MWCNT/polymer nanocomposite depends on the dispersion of MWCNTs in the matrix and interfacial interactions between the MWCNT and the polymer. The existence of agglomerates will lead to more voids in the bulk materials and finally deteriorate the overall properties. As we mentioned in question 5, the uniform dispersion of MWCNTs was better after functionalized with the assist of heating and sonication process. However, when the higher MWCNTs content than 4% applied, the incompatibility in phases between the matrix and MWCNTs were appeared and resulted in dispersion of MWCNT agglomerates and mixing them with the polymer matrix. The reason is that the difficulties associated with dispersion of entangled MWCNT during printing processing with small size of injection head and poor interfacial interaction between MWCNTs and polymer matrix.

In addition to the above comments, the regular edit checks the grammar, spelling, punctuation and phrasing have been corrected in revised manuscript (by English editing services of MPDI)

We look forward to hearing from you in due time regarding our submission and to respond to any further questions and comments you may have.

Please see the attached a revised version of the manuscript.

Sincerely,

Le Thai Hung

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The paper is ready to publish.