Functionalization of Continuous Fiber-Reinforced Thermoplastic Pultrusion Profiles by Welding

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article explores a novel method for functionalizing thermoplastic pultrusion profiles using a thermal welding process. The authors focus on welding unfilled PA6 to PA6 profiles reinforced with continuous glass fibers, produced through in-situ pultrusion.

Key findings of this article:

• Weldability of the profiles:
  The study demonstrates that it is possible to weld thermoplastic pultrusion profiles with a high fiber content (approximately 70% by volume), despite the challenges posed by the limited amount of polymer matrix available for fusion and diffusion.

• Unique welding mechanism:
  Unlike classical polymer welding theories, which emphasize molecular interactions, the welding of pultrusion profiles appears to rely on a macroscopic mechanism. Applying high interfacial pressure causes transverse flow of the molten unfilled PA6, which mixes with the matrix of the fiber-reinforced profile.
  This mixture creates interlocking between the continuous fibers and the unfilled PA6, ensuring a strong mechanical bond.

• Mechanical performance:
  Tensile and bending tests reveal that the welded joints can achieve high strength, comparable to or even exceeding that of short-fiber-reinforced PA6 systems reported in the literature.
  The welding factors (ratio between the strength of the welded joint and the base material) exceed 1, indicating that the presence of fibers in the weld interface contributes to the joint's strength.

The article shows promise but requires significant revisions to enhance its clarity and depth.

1. Lack of clarity in results presentation:
   While the article presents interesting results, their presentation could be improved:

   • For instance, Figure 3a shows tensile strength as a function of the test series number, but it would be more relevant to present it as a function of the varied welding parameters (e.g., heating time, interfacial pressure, IR emitter power).
   • Similarly, Figure 4a uses the energy introduced by the IR emitter as the independent variable, but directly using welding parameters would make the results easier to interpret.

2. Limited discussion on theinfluence of crystallization:
   The article mentions the importance of PA6 crystallization on the efficiency of the welded joints but does not delve into this aspect.
   A more detailed discussion of how welding parameters affect the crystallization of PA6 in the weld zone is necessary.

3. Absence of penetration depth analysis:
   The article notes that the penetration depth of the pulling rod into the pultruded material can reach up to 1 mm but does not analyze this further.
   A deeper study on how interfacial pressure and applied energy influence penetration depth and the formation of the mixing zone would be valuable.

4. Lack of comparison with otherjoining techniques:
   The article focuses solely on thermal welding, but it would be beneficial to compare this technique with other joining methods for thermoplastic pultrusion profiles.

The article offers an interesting contribution to the field of fiber-reinforced plastic welding. However, significant revisions are needed to improve the clarity of results presentation, deepen the analysis of the welding mechanisms, and discuss the limitations and perspectives of the proposed technique. The article has strong potential but requires refinement to fully realize its impact.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors present an initial experimental parameter study on the welding of polyamide profiles, specifically combining profiles with and without fiber reinforcement. The mechanical performance is assessed under tensile and bending loads. Unfortunately, the reviewer must report substantial deficiencies in the manuscript's current form. A holistic revision is recommended before consideration for publication elsewhere.

From a scientific perspective, the absence of sufficient primary literature significantly limits the ability to contextualize the work's relevance. The research objectives are not clearly stated and subsequently lack a coherent resolution in the conclusions. Missing information, particularly concerning relevant material characteristics and mechanical testing, prevents reproducibility. Quantitative data is often inadequately contextualized, methodological decisions are frequently unexplained, and limitations are either absent or insufficiently discussed. Photographs of the samples and the setups would significantly aid in understanding.

The reviewer refrains from providing detailed line-by-line suggestions but will address distinct areas of concern in the manuscript as follows:

L98 Terms like "not too low" and "not too high" require specific values or definitions

L100 Which specific results did the authors observe?

L192 Avoid rhetorical questions

L243 Clarify the meaning of "heating pressure"

L252 The parameters are critical factors, see Table 1. How did the authors determine their optimal configuration to justify not varying them?

L285 Assuming a (constant) cross-section is not valid

L325 The reasoning behind "dimensional load paths" is difficult to follow

Fig1 A sequence of images would improve clarity

Fig2 Detail the clamping method

Fig3 The standard deviation’s lower range cannot be less than zero MPa. please review the data for accuracy.

In summary, a thorough and comprehensive revision is necessary to meet publication standards.

Comments on the Quality of English Language

The considerable issues in presentation make it difficult to fully assess the scientific content. The language (e.g., precision, neutrality, logical coherence, conciseness) does not meet the standards for a scientific paper, severely interrupting the reading flow. Additionally, numerous trivial statements, filler sentences, and unsupported assertions inflate the manuscript. Section 2.4 consists of a single sentence. The text appears to have been automatically translated into English, also indicated by misinterpreted technical terms. Furthermore, minor but noticeable formatting errors (e.g., misplaced citations, incorrect italics in indices, issues with parentheses) reveal a lack of attention to detail.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The following points may be included to improve the clarity of the manuscript.

1. The basis of selected process parameters in table 2 may be included. Such DOE or any other basis if any

2. how many repetitions are conducted for each sample. If only one experiment , how to ensure statistical deviation of the readings.

3. While citing the figures in text, refer by figure number such as Fig 3 a and 3b ( example line 372) not by first line etc.

4. Conclusions to highlight the outcome of the experiment results.

Comments on the Quality of English Language

Few sentences and nomenclature may be revised, For example use section 2.3 instead of chapter 2.3

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Overall Recommendation

      Overall, the manuscript presents valuable research on Functionalization of Continuous Fiber-Reinforced Thermo-2 plastic Pultrusion Profiles by Welding. Addressing the suggestions for improvement would enhance the clarity and impact of the study.

1.     Check your paper title capitalization. Capitalize the first letter, all nouns, all verbs (even short ones, like is), all adjectives, and all proper nouns. That means you should lowercase articles, conjunctions, and prepositions

2.     Abstract should be re-written, and it should orderly consist of the purpose of the study, approach/detailed procedure, and main results (not the details). To improve readability and accessibility, the authors could consider simplifying some technical terms and ensuring the purpose and conclusions are as precise as possible.

3.     Overall, the introduction presents a thorough background but would benefit from a clearer statement of the research gap and objectives. Section Introduction should orderly present background/motivation, literature survey, purpose of the study, organization of the paper.

4.     Enhance the quality of the figures, all the figures should be clear and sharp, and the text in the figure should be readable.

5.     The conclusion should summarize the key findings of the study and highlight their significance. Consider revising the conclusion to provide a more focused and concise summary.

6.     Results statements could be much better and better citations could be done accordingly to your results. Suggesting the following papers for Reference and citations.

https://doi.org/10.3390/micro4040039

https://doi.org/10.1016/j.matpr.2020.04.902

Comments on the Quality of English Language

NA

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

All recommandation are OK.

Author Response

Dear Reviewer,

Thank you again for your helpful comments.
This has considerably improved the quality of the article.

No changes have been made to the article based on the reviews.

We are already looking forward to its publication.

Best regards
Calvin Ebert

Reviewer 2 Report

Comments and Suggestions for Authors

The reviewer appreciates the effort the authors have put into revising the manuscript. The reviewer acknowledges that the manuscript has significantly improved in clarity and overall quality and therefore recommends its publication in its revised form. For future submissions, please ensure all line numbers are included in the response-to-reviewer document. Nevertheless, I was able to locate the relevant paragraph in the manuscript.

Author Response

Dear Reviewer,

Thank you again for your helpful comments.
This has considerably improved the quality of the article.

No changes have been made to the article based on the reviews.

We are already looking forward to its publication.

Best regards
Calvin Ebert

Reviewer 3 Report

Comments and Suggestions for Authors

Conclusions are revised; however future research directions are nor warranted. usually review papers can include research questions and future directions.

Also, conclusions not to include references

Author Response

Dear Reviewer,

Thank you again for your helpful comments.
This has considerably improved the quality of the article.

Comment 1:
Conclusions are revised; however future research directions are nor warranted. usually review papers can include research questions and future directions.

Response 1:
The proposed research questions are derived directly from this work and show where further experimental tests are necessary to better understand and further optimize the welding of the pultruded profiles. This distinguishes the outlook in our article from a review paper in which research questions on an entire field of research are compiled. 
We also believe that the further considerations will enhance the understanding of the contents of the article. We therefore advocate leaving the paragraph in the article.

Comment 2:
Also, conclusions not to include references

Response 2:
By including references, the statements in the conclusion can be quickly categorized and the reader does not have to scroll back to the section which deals with the theoretical background. We therefore consider it useful to include a few references in the conclusion. 

No changes have been made to the article based on our responses.

Best regards
Calvin Ebert

 

Reviewer 4 Report

Comments and Suggestions for Authors

Accept in present form

Comments on the Quality of English Language

Quality of English Language are good 

Author Response

Dear Reviewer,

Thank you again for your helpful comments.
This has considerably improved the quality of the article.

No changes have been made to the article based on the reviews.

We are already looking forward to its publication.

Best regards
Calvin Ebert