Synergistic Effect of PBz/Epoxy/PCLA Composite Films with Improved Thermal Properties
, Shakila Parveen Asrafali 1,†, Seongcheol Kim 2 and Jaewoong Lee 1,*Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis manuscript presented an interesting study of PBz/Epoxy/PCLA composite which demonstrated improved improved thermal stability. I would recommend the acceptance for publication if the authors address the following problems.
1. Please go through the entire manuscript to correct typos and provide full name for the abbreviations as they first appear in the manuscript. For example, "PCLA", "CPLA", "DMSO", "PBA" etc.
2. A minor issue with Figure 1, although it does not affect the point you are making, it would be good to correct the baseline as the transmittance shouldn't go above 100%.
3. Please mark (a~d) in figure 3 and delete "water contact angle analysis" in the caption (line 269).
4. The authors argued that the xrd results show uniform dispersion of caprolactam. Is it possible to add the xrd profile of PCLA only as a reference?
5. SEM showed separation of material into two domains of PBz/Epoxy and PCLA which contradict the conclusion from XRD.
6. The AFM scans should have color scales. Could the authors provide the roughness from the AFM scans for comparison?
7. Could the authors provide similar optical images of other films other than PBz/Eproxy/PCLA50?
Comments on the Quality of English LanguageEnglish language is easy to read and understand.
Author Response
Response to reviewer comments
- Please go through the entire manuscript to correct typos and provide full name for the abbreviations as they first appear in the manuscript. For example, "PCLA", "CPLA", "DMSO", "PBA" etc.
Response: The entire manuscript has been checked for typo errors and abbreviations and changes have been made wherever required.
- A minor issue with Figure 1, although it does not affect the point you are making, it would be good to correct the baseline as the transmittance shouldn't go above 100%.
Response: As suggested by the reviewer, the baseline for FT-IR has been corrected and the figure has been replaced. Kindly refer to Figure 1.
- Please mark (a~d) in figure 3 and delete "water contact angle analysis" in the caption (line 269).
Response: The markings, a – d, has been made in Figure 3. Kindly refer to Figure 3. And also ‘water contact angle analysis’ in the caption has been removed.
- The authors argued that the xrd results show uniform dispersion of caprolactam. Is it possible to add the xrd profile of PCLA only as a reference?
Response: The XRD of PCLA has been included. Kindly refer to Figure 5.
- SEM showed separation of material into two domains of PBz/Epoxy and PCLA which contradict the conclusion from XRD.
Response: The amorphous nature of the PBz/Epoxy is not disturbed by the addition of PCLA, whereas the surface topography is different for the PBz/Epoxy and PBz/Epoxy/PCLA films.
- The AFM scans should have color scales. Could the authors provide the roughness from the AFM scans for comparison?
Response: As suggested by the reviewer, the AFM images has been provided with color scales and roughness. Kindly refer to Figure 7.
- Could the authors provide similar optical images of other films other than PBz/Eproxy/PCLA50?
Response: For the present study, we did not take the optical images for all the films, due to unavailability of the instrument. We assure to do in our future studies.
Reviewer 2 Report
Comments and Suggestions for AuthorsThe publication discusses the issue of producing PBz/Epoxy/PCLA foil in order to reduce the brittleness of PBz. No changes in curing exotherm were noted based on DSC tests. It was reported that the heat released during the exotherm (ΔH) drops dramatically from 121 J/g to 84 J/g, indicating that the benzoxazine content is very important. This is due to the fact that it takes part in the polymerization process by opening the oxazine ring. It was also noticed that exceeding 50 wt. CPL results in agglomeration and leads to phase separation. There was also an increase in the thermal stability of the PBz/Epoxy/PCLA30 composite film at a degradation temperature of 438oC, compared to the composite without PCLA. The research results provide direction for the development of modern composites and their films in the melt mixing process, maintaining and optimizing their properties. The work is interesting, but I have some comments and questions regarding its assessment:
1. Figure 2 - the values on the scales are illegible.
2. Table 1 - the quality should be improved because the values are difficult to read.
3. The work contains numerous editing errors regarding justification, line spacing and chapters.
4. Why use 10, 30 and 50% e-caprolactam?
5. Was the experimental design method used?
6. Were the results statistically processed?
7. Was the test used to optimize the content of individual components of the composite?
8. Do the authors plan additional research on the adhesion of individual components of the composite?
Author Response
Response to reviewer comments
- Figure 2 - the values on the scales are illegible.
Response: Figure 2 has been replaced with legible scale values. Kindly refer to Figure 2.
- Table 1 - the quality should be improved because the values are difficult to read.
Response: As mentioned by the reviewer, the quality of Table 1 has replaced with readable values. Kindly refer to Table 1.
- The work contains numerous editing errors regarding justification, line spacing and chapters.
Response: The manuscript has been thoroughly checked for editing errors, line space and chapters wherever required and corrected accordingly.
- Why use 10, 30 and 50% e-caprolactam?
- Was the experimental design method used?
- Were the results statistically processed?
- Was the test used to optimize the content of individual components of the composite?
Responses for 4-7: We expect cross-linking reactions between polybenzoxazine, epoxy and polycaprolactam. As we want to see the effect of caprolactam addition, we fixed the weight of benzoxazine and epoxy, and varied caprolactam alone. And so, we fixed the minimum weight of caprolactam to be 10% and not to exceed the overall weight of benzoxazine and epoxy, the maximum weight of caprolactam was fixed to be 50%.
- Do the authors plan additional research on the adhesion of individual components of the composite?
Response: We plan to prepare similar kind of films with different benzoxazine monomers for our future work.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe article may be published in the journal Sustainability after minor revision.
Notes
The title of the article should indicate that the thermal and fire-retardant properties of films are improved.
Introduction
In the Introduction section, it is necessary to provide a rationale for the choice of epoxy resins to increase the strength of polybenzoxazines, and to analyze the current state of research in the field of application of epoxy resins. In particular, it is proposed to use references to the works of Chistyakov E.M. (Scopus No. 51260935700), in which epoxy composites with increased fire resistance, heat resistance and glass transition temperature were obtained.
Materials and methods
The epoxy equivalent and viscosity of the epoxy resin used should be stated.
Scheme 1 – instead of farmaldehyde, it is necessary to write paraformaldehyde in the form (СH2O)n, since formaldehyde is a gas.
The resolution of the optical microscope should be indicated and a description of the XRD and AFM methods, as well as the characteristics of the goniometer, should be provided.
Results and discussion
The IR spectrum of benzoxazine should indicate vibrations of the bond of the methylene group of the oxazine ring. The product is soluble in solvents for NMR spectroscopy. In my opinion, it was necessary to present the IR spectra of the resulting films, and not of the benzoxazine monomer.
In Figure 3 the letters a, b, c… should be given.
Instead of caprocatam you should write caprolactam (line 274).
What causes the increase in LOI of films when adding CPLA? A detailed explanation should be provided.
Сonclusions
Where are you planning to use the resulting films?
Author Response
Response to reviewer comments
Notes
The title of the article should indicate that the thermal and fire-retardant properties of films are improved.
Response: The title of the article has been modified as suggested by the reviewer. The modified title is, ‘Synergistic effect of PBz/Epoxy/PCLA composite films with improved thermal properties’.
Introduction
In the Introduction section, it is necessary to provide a rationale for the choice of epoxy resins to increase the strength of polybenzoxazines, and to analyze the current state of research in the field of application of epoxy resins. In particular, it is proposed to use references to the works of Chistyakov E.M. (Scopus No. 51260935700), in which epoxy composites with increased fire resistance, heat resistance and glass transition temperature were obtained.
Response: As suggested by the reviewer, the reference works related to epoxy composites have been included in the introduction part. Kindly refer to the highlighted part of the introduction.
Materials and methods
The epoxy equivalent and viscosity of the epoxy resin used should be stated.
Response: The details regarding the epoxy equivalent and viscosity of the epoxy resin has been included in the materials section and highlighted for your reference.
Scheme 1 – instead of farmaldehyde, it is necessary to write paraformaldehyde in the form (СH2O)n, since formaldehyde is a gas.
Response: The correction suggested by the reviewer has been incorporated in Scheme 1. Kindly refer to Scheme 1.
The resolution of the optical microscope should be indicated and a description of the XRD and AFM methods, as well as the characteristics of the goniometer, should be provided.
Response: The description of the instruments including XRD, AFM, goniometer and resolution of optical microscope has been included in the instrumentation section.
Results and discussion
The IR spectrum of benzoxazine should indicate vibrations of the bond of the methylene group of the oxazine ring. The product is soluble in solvents for NMR spectroscopy. In my opinion, it was necessary to present the IR spectra of the resulting films, and not of the benzoxazine monomer.
Response: As suggested, the vibrations of the methylene group of oxazine ring has been indicated. The IR spectra of the films have been included. Kindly refer Figure 4.
In Figure 3 the letters a, b, c… should be given.
Response: Figure 3 has been replaced including the labels a-d.
Instead of caprocatam you should write caprolactam (line 274).
Response: The mentioned correction has been made for caprolactam.
What causes the increase in LOI of films when adding CPLA? A detailed explanation should be provided.
Response: The formation of cross-linked structure, together with hydrogen bonding interactions and amide linkage increased the LOI of the films. The explanation has been included in the results part of the manuscript and highlighted for your reference.
Сonclusions
Where are you planning to use the resulting films?
Response: The prepared films can be used for advanced composite applications requiring excellent thermal and flame-retardant properties. This has been mentioned in the conclusion part and highlighted.
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors responded to my comments. I accept the current version of the publication.
