Nanomaterial-Enhanced Sizings: Design and Optimisation of a Pilot-Scale Fibre Sizing Line
, Ioannis Papadopoulos 1, Stavros Anagnou 1, Behnam Dashtbozorg 2, Xiaoying Li 2, Hanshan Dong 2 and Costas A. Charitidis 1,*
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn this paper, the optimization of key process parameters for the functioning of the pilot-scale sizing line has been performed. The presented information is highly relevant for Fibers journal and must be interesting for its readers. The manuscript is clearly written, but poorly illustrated. Before the acceptance for publication in Fibers, the quality of figures must be improved substantially. The comments are listed below.
Comments and suggestions:
1) Materials and Methods (Line 93): What about the composition and concentration of surface functional groups in CNTs and FLGs after their functionalization? The characteristics of used materials – CNTs and FLGs – should be presented in this section.
2) Materials and Methods (Lines 190-195): The temperature range for TG analysis (minimum and maximum T) should be mentioned.
3) General note: the quality of Figures must be improved!
Ø Fig.2 (с) – the scale is hardly visible
Ø Fig.3 (d), (e) and (f) – scale bars are almost invisible, some writings are too small.
Ø Figures 4, 5, 8 – scale bars are poorly seen. Make them more distinct.
Ø Fig.7 – scale bars are almost invisible, especially for the enlarged fragments.
Ø Fig.9 – change the color of numbers to make readers see them.
Ø Fig.10 – the resolution of picture is low.
4) Figure 6 must be reformatted and improved. Adjust the scale of y-axis to make the effects on TGA curves more visible. As for the x-axis, it should be replotted from time (t, min) to temperature (T, °C). The writings should be enlarged.
5) Lines 433-435, 478-485, 493-501: Please, suggest the explanation why less agglomerates are observed for CNT-N2 sized fibres? What is the reason for superior results in case of using CNT-N2 and FLG-N2 as sizing agents? The same assumption is expected to be made in Conclusion.
Comments on the Quality of English Language
Typos and grammar:
1) Table 3: The parameter “Tg (°C)” should be decoded
2) Lines 394, 395, 434: subscript symbols (N2, O2,..) should be corrected
3) Lines 412-414: The sentence “ ..by studying the duration that a stable solution…”should be rephrased
4) Lines 460-462: the phrase “… in Table 6, of desized fibres…” should be reconstructed
Author Response
1) Materials and Methods (Line 93): What about the composition and concentration of surface functional groups in CNTs and FLGs after their functionalization? The characteristics of used materials – CNTs and FLGs – should be presented in this section.
XPS results were included in the supplementary file.
2) Materials and Methods (Lines 190-195): The temperature range for TG analysis (minimum and maximum T) should be mentioned.
Added in line 196
3) General note: the quality of Figures must be improved!
Ø Fig.2 (с) – the scale is hardly visible
Fig 2 was adjusted
Ø Fig.3 (d), (e) and (f) – scale bars are almost invisible, some writings are too small.
Figure 3 was adjusted
Ø Figures 4, 5, 8 – scale bars are poorly seen. Make them more distinct.
Figures are as extracted from the SEM instrument. No adjustment has been made. The editorial board could enlarge the images. Quality and resolution are considerably high (~3MB per image) for the scale bar to be easily visible.
Ø Fig.7 – scale bars are almost invisible, especially for the enlarged fragments.
The enlarged fragments are a x20000 magnifacation, while the original x1000. This info was included in the figure caption. Figure images were remained unchanged from the original that were extracted from SEM instrument. Image quality is considerably high and considering there is an option for the readers to browse all the figures in the original size, distinguishing the scale bars will not be a problem.
Ø Fig.9 – change the color of numbers to make readers see them.
Done
Ø Fig.10 – the resolution of picture is low.
Figure was replaced. Although we should double check the original files, since all images were submitted in separate file, with high quality. Probably when transferred to a word file, quality is lowered. In any case, all readers have the option to browse through the original file of images, so quality will not be an issue.
4) Figure 6 must be reformatted and improved. Adjust the scale of y-axis to make the effects on TGA curves more visible. As for the x-axis, it should be replotted from time (t, min) to temperature (T, °C). The writings should be enlarged.
The y axis was originally in a scale to facilitate the better understanding of the graph. X axis has been change to temperature and quality of image was increased.
5) Lines 433-435, 478-485, 493-501: Please, suggest the explanation why less agglomerates are observed for CNT-N2 sized fibres? What is the reason for superior results in case of using CNT-N2 and FLG-N2 as sizing agents? The same assumption is expected to be made in Conclusion.
Added a paragraph in the results section and conclusions:
Results: The enhanced performance of N2-functionalized nanoparticles can be attributed to their chemical affinity with the sizing solution. As shown in Table 2, HP206 is amine-dispersed, while N2 functionalization introduces C-N bonds, as confirmed by XPS results (see supplementary file). The incorporation of C-N bonds contributes to a stronger chemical affinity compared to O2 functionalization, which introduces C-O bonds. Although NH3 functionalization also introduces C-N bonds, the quantity is considerably lower than in N2 functionalization (Area of C-N bond in C1s scan: 4.1% for NH3 FLG compared to 4.7% for N2 FLGs and 0.49% for NH3 CNTs compared to 1.78% for N2 CNTs). This variation accounts for the superior overall properties associated with N2 functionalization.
Conclusions: Improved chemical affinity of sizing solution (amined-dispersed) with N2 function-alized CNTs/FLGs is attributed to the addition of C-N bonds, surpassing both (a) the C-O bonds introduced by O2 plasma functionalization and (b) the quantity of C-N bonds in NH3 plasma functionalization.
1) Table 3: The parameter “Tg (°C)” should be decoded
Done
2) Lines 394, 395, 434: subscript symbols (N2, O2,..) should be corrected
Done
3) Lines 412-414: The sentence “ ..by studying the duration that a stable solution…”should be rephrased
Done. Sentence was replaced by :Initial enhancements could be achieved by investigating the duration for which a stable solution can be maintained during the preparation of the sizing solution, without the occurrence of agglomerates or sediment formation.
4) Lines 460-462: the phrase “… in Table 6, of desized fibres…” should be reconstructed
Done. Sentence was replaced by “ Upon comparing the results presented in Table 6 for desized fibers and Michelman-sized fibers, it is evident that the latter outperformed in both tensile and 3PB strength.”
Reviewer 2 Report
Comments and Suggestions for AuthorsSemitekolos et al. presented a study on the pilot-scale sizing processing of carbon fibers including the use of nanomaterials with different morphology and surface chemistry. The technical contents are rigorous and the manuscript is well written. I recommend publication with minor modification. See comments below:
At line 98, it is worth mentioning what chemical groups are produced and add it to the discussion at around line 477.
What explains the weight drop shown in Figure 6 from 15 to 34 min?
What is the black spot in Figure 2a?
At line 392, why is it that "conventional metrics of agglomeration and distribution cannot be applied"?
The contact angle characterization in section 3.3.2 is affected by the surface microstructure in the case of CNT sized fibers. How does the surface tension measurement take into account of different wetting states such as the Wenzel and Cassie-Baxter state?
Author Response
At line 98, it is worth mentioning what chemical groups are produced and add it to the discussion at around line 477.
XPS results were included in the supplementary file.
What explains the weight drop shown in Figure 6 from 15 to 34 min?
The graph has been adjusted and X axis now is showing temperature instead of time. From 350 to 750 oC there a negligible weight loss for both cases (less than 1%), that can’t be attributed to decomposition, evaporation, or any other chemical reaction. This is also indicated in text line 349.
What is the black spot in Figure 2a?
CFs. Added in line 260.
At line 392, why is it that "conventional metrics of agglomeration and distribution cannot be applied"?
FLGs are not able to be observed through SEM due to their structure, as CNTs, so we are not able to perform picture analysis (the means to observe the agglomeration/ distribution) as we did for CNT images.
The contact angle characterization in section 3.3.2 is affected by the surface microstructure in the case of CNT sized fibers. How does the surface tension measurement take into account of different wetting states such as the Wenzel and Cassie-Baxter state?
Authors would like to clarify that they performed qualitative assessment of wettability, by measuring the contact angle of a resin droplet applied on the CF surface and not surface tension measurement. A contact angle closer to 0 degrees indicates complete wetting (Wenzel state), while a contact angle greater than 90 degrees suggests partial wetting (Cassie-Baxter state). In order to take into consideration, the different states, more characterisations had to take place like AFM or CAG with multiple liquids to examine the surface roughness and the surface energy correspondingly. However, since our investigation is focused on comparing the different sizing materials and all experiments have been performed under the same circumstances, we consider safe to make the conclusion that wettability for specific cases is improved. A wider analysis could potentially follow in a future work. We have found similar works in the literature. Thank you for the suggestion.
https://www.sciencedirect.com/science/article/pii/S1359836822001342
Reviewer 3 Report
Comments and Suggestions for AuthorsCarbon nanomaterials (graphene, carbon nanotubes, fullerenes, etc.) have excellent physical and chemical properties, such as high electrical and thermal conductivity, chemical stability, corrosion resistance, high specific surface area, etc. Polymers reinforced with carbon materials, in particular Carbon fibers (CF) are an integral part of modern and future materials. The relevance of the article is due to the development and research of industrial technology for the production of hydrocarbons with specified properties based on the calibration of hydrocarbons as a continuous process. The authors of the article propose the development and optimization of a pilot project for obtaining CF sizing is a continuous process on an industrial scale. As the authors of the article note, processing using the sizing method is considered a simple, cost-effective procedure. Moreover, CFs modified with carbon nanomaterials (graphene and CNTs) have increased affinity for the polymer matrix. The purpose of the work is to study all the parameters for applying a uniform coating to the surface of a carbon fiber under optimal conditions and obtaining fibers with increased multifunctional properties due to the inclusion of nanomaterials. The article corresponds to the topic of the journal. Well illustrated. However, it has a number of comments and requires some clarification.
1) In the Introduction, it is necessary to expand the citation and add microwave exposure to the listed methods of processing materials 1. [DOIhttps://doi.org/10.1039/C9NA00538B]; 2. [https://doi.org/10.1002/pen.26498]
2) The article does not present the characteristics of the MWCNT and graphene materials that were added to the solution. In line 81, the authors of the article talk about the use of multilayer carbon tubes (MWCNT). However, line 93 states that CNTs were added to the solution, i.e. single-layer. Still, what carbon nanotubes were used in the work?
3) From Figure 1 it is not clear what the line productivity is per hour, per day, etc.? Is the hardware design presented in Figure 1 used in real production?
4) It is not clear what surfactants were added to the solution to modify CF and how they affect the final product?
5) The conclusions must indicate how the CF treatment affects the performance and quality of the final product, as well as the affinity with the polymer matrix.
Author Response
1) In the Introduction, it is necessary to expand the citation and add microwave exposure to the listed methods of processing materials 1. [DOIhttps://doi.org/10.1039/C9NA00538B]; 2. [https://doi.org/10.1002/pen.26498]
Added in line 51.
2) The article does not present the characteristics of the MWCNT and graphene materials that were added to the solution. In line 81, the authors of the article talk about the use of multilayer carbon tubes (MWCNT). However, line 93 states that CNTs were added to the solution, i.e. single-layer. Still, what carbon nanotubes were used in the work?
XPS results were included in the supplementary file.
3) From Figure 1 it is not clear what the line productivity is per hour, per day, etc.? Is the hardware design presented in Figure 1 used in real production?
Added production range at the description of feed roller system. The line is identical to the one presented in figure 1.
4) It is not clear what surfactants were added to the solution to modify CF and how they affect the final product?
An analytic approach of how these dispersions were made was included in the supplementary file.
5) The conclusions must indicate how the CF treatment affects the performance and quality of the final product, as well as the affinity with the polymer matrix.
From XPS analysis N2 plasma functionalization introduces C-N bond while O2 C-O bonds. Results proved that both functionalization increase the adhesion, however C-N increase it more. This was included in the conclusion section as suggested and in the results with more details.
