Recycled Glass Polypropylene Composites from Transportation Manufacturing Waste

Round 1

Reviewer 1 Report

The submitted manuscript cannot be accepted for publication in this form, but it has a chance of acceptance after a minor revision. My comments and suggestions are as follows:

1- Abstract gives information on the main feature of the performed study, but some details about the obtained results must be added. However, a concise abstract is needed.

2- Authors must clarify necessity of the performed research. Aims and objectives of the study, and also differences with the previous review papers must be clearly mentioned.

3- The literature study must be enriched. For instance, authors must read and refer to the relevant papers: (a) https://doi.org/10.1016/j.compstruct.2018.05.043 (b) https://doi.org/10.1016/j.compscitech.2018.04.016 and other research works.

4- Authors must clearly emphasized the limitations and strengths of their study.

5- The current version of introduction is too short.

6- It seems the manuscript is prepared without care. For example, see the Fig. I, where the text inside the figure is not complete. Scale bar for Fig. 3 is necessary, and so on.

7- Why this particular materials are considered for this study? Scientific reason must be discussed.

8- All figures and curves must be illustrated in a high quality.

9- Reasons of different failure loads in Fig. 14 must be discussed.

10- Details of calculations of determining the flexural strength must be added.

11- The curves must be illustrated in a more scientific way. For example, deviation (error bars) should be added. Also, there are sentences which have to be rewritten.

12- The conclusion must be more than just a summary of the manuscript. List of references must be updated based on the proposed papers. Please provide all changes by red color in the revised version.

 

 

Author Response

Responses are provided in Blue

The submitted manuscript cannot be accepted for publication in this form, but it has a chance of acceptance after a minor revision.

Thanks

My comments and suggestions are as follows:

• Abstract gives information on the main feature of the performed study, but some details about the obtained results must be added. However, a concise abstract is needed.

The abstract has been updated with more specific details as suggested by the reviewer. Thanks.

• Authors must clarify necessity of the performed research. Aims and objectives of the study, and also differences with the previous review papers must be clearly mentioned.

The Introduction section (pages 1 and 2) highlighted in blue very much addresses the reviewer’s points. We have made clear the necessity of the research in terms of reduced landfill and pathways for recycling/circular economy approach.

Pages 2 and 3 outlined the literature conducted by other researchers that addresses recycling different ways. Yet the differentiation of their works with the present study is outlined in the literature review as well.

• The literature study must be enriched. For instance, authors must read and refer to the relevant papers: (a) https://doi.org/10.1016/j.compstruct.2018.05.043(b) https://doi.org/10.1016/j.compscitech.2018.04.016 and other research works.

The reference(s) suggested have NO relevance to our work and we respectfully decline to include these.  

https://doi.org/10.1016/j.compstruct.2018.05.043 - Mohammad Reza, Khosravani, KerstinWeinberg, Composite Structures, Volume 197, 1 August 2018, Pages 80-88, Characterization of sandwich composite T-joints under different ageing conditions

This suggested paper has no relevance to our study and we unfortunately cannot include it.

https://doi.org/10.1016/j.compscitech.2018.04.016  N.K.Kim, S.Dutta, D.Bhattacharyya, Composites Science and Technology, A review of flammability of natural fibre reinforced polymeric composites, Composites Science and Technology, Volume 162, 7 July 2018, Pages 64-78.

• Authors must clearly emphasize the limitations and strengths of their study.

We have provided an objective and quantitative bounds of properties from the recyclate variants. There are no limitations in terms of scale able process(es), which can also be considered as a strength. We have indicated these points on Pages 18 (Scale-up) and 19 (last point in the Conclusions section) respectively.

• The current version of introduction is too short.

We respectfully disagree. We have provided a concise Introduction to make the relevant points. Expanding it would add more length, but the message is already clear in the current version.

• It seems the manuscript is prepared without care. For example, see the Fig. I, where the text inside the figure is not complete. Scale bar for Fig. 3 is necessary, and so on.

Thanks for these points. We have made the corrections.

• Why this particular materials are considered for this study? Scientific reason must be discussed.

We had indicated this on Page 3. The materials rationale is that these were the primary waste generated from trailer manufacturing. We have highlighted this section in blue again.

• All figures and curves must be illustrated in a high quality.

The figures and curves have been checked for readability.

• Reasons of different failure loads in Fig. 14 must be discussed.

The reasons for flexural failure loads are provided at the bottom of Page 13. This has been highlighted again in blue color.

• Details of calculations of determining the flexural strength must be added.

On Page 12 we have provided the ASTM standard D790 as the reference for flexural strength. With the standard provided, all the calculations are made per this standard, hence we have been repeatedly advised in other submissions not to add redundant calculations. Hence we have been diligent not to include known equations from ASTM standards. In this case ASTM D 790.

• The curves must be illustrated in a more scientific way. For example, deviation (error bars) should be added. Also, there are sentences which have to be rewritten.

Table 4 and Figure 15 provide the standard deviation and the error bars respectively. Figure 14 simply provides the load-deflection curve for indication of individual variant response. Without knowing which sentences have to be rewritten it was not possible to imagine which ones were in question. We have reviewed the write up carefully for English tense, grammar and syntax. We believe this addresses the reviewer’s points.

12- The conclusion must be more than just a summary of the manuscript. List of references must be updated based on the proposed papers. Please provide all changes by red color in the revised version.

Please see our response to the proposed papers. So, we have not updated the reference list. The conclusion has been updated to be more than a summary as suggested by the reviewer.

Reviewer 2 Report

In this manuscript, the author investigated the effect of processing parameters on the properties of recycled glass polypropylene composites, which is a meaningful work. The whole manuscript was in bad and writing, and my comments are summarized below.

(1) The section of “2. Literature review” should be included in the “1. Introduction.”

(2) The location of Figure 1, 2 and table 1 should revised.

(3) The fiber content in table 1 is not consistent with that present in table 2 (fiber weight fraction), which should be revised.

(4) Line 120-121, how can you determine the fiber weight fraction only from the SEM? As only morphology can be observed from SEM image. For figure 3, the sentence “This indicates the as-received material had very high fiber content, >70 wt%.” should not appeared in the caption.

(5) Why there is a vertical weight loss around 240°C in Figure 5? Which should be explained. In addition, the TGA curve of the as-processed plate should be provided.

(6) Figure 7 should present before “4.2 tensile response”. Why does the crystallinity of the ECM processed materials was higher? Which should be explained.

(7) How is the mechanical properties for the as-received materials? In addition, the mechanical properties of the as-received materials should compared with the as-processed mterials.

(8) The format of from table 3 to figure 13 should be revised.

Author Response

Responses provided in Blue color.

In this manuscript, the author investigated the effect of processing parameters on the properties of recycled glass polypropylene composites, which is a meaningful work. The whole manuscript was in bad and writing, and my comments are summarized below.

The manuscript has been carefully checked for grammar, syntax, tense and logical flow.

• The section of “2. Literature review” should be included in the “1. Introduction.”

 

We believe separating the Introduction from Literature Review provides the reader a logical transition. Hence, we would prefer to keep it separate.

 

• The location of Figure 1, 2 and table 1 should revised.

The location is adjusted now as follows – Figure 1 – Table 1 – Figure 2 in order of ther mention in the text.

• The fiber content in table 1 is not consistent with that present in table 2 (fiber weight fraction), which should be revised.

Thank you for this note. However, we would like to clarify that Table 1 is Summary of scrap PP-GF material in combination with virgin PP while Table 2 is the ‘fiber weight fraction in recyclate’. Table 2 is the fiber fraction in the recyclate only. Also see Lines 108-110 and Lines 156-157 respectively.  So we had represented these correctly and did not want to revised it since it was correct to begin with.

• Line 120-121, how can you determine the fiber weight fraction only from the SEM? As only morphology can be observed from SEM image. For figure 3, the sentence “This indicates the as-received material had very high fiber content, >70 wt%.” should not appeared in the caption.

Actually, the confusion may have been in the way it was worded. Please see new line numbers 150-153 where we have clarified it. We mainly wanted to convey via Figure 3 that the fibers are dry indicating high fiber content and less resin content. The actual value of 70wt% was obtained from burn-off studies, and not from SEM. The wordings have been clarified.

• Why there is a vertical weight loss around 240°C in Figure 5? Which should be explained. In addition, the TGA curve of the as-processed plate should be provided.

Actually, that is an artifact of the loss of data in the very early portion and should be discounted. The data starts plotting from 98% and is consistent from this point on. We have made a note in the caption of Figure 5 indicating this.  Since this is a machine generated plot on a printer, and not in ASCII format. we were not able to re-plot. Thanks for allowing us to respond to this.

• Figure 7 should present before “4.2 tensile response”. Why does the crystallinity of the ECM processed materials was higher? Which should be explained.

Figure 7 has been moved to before the Tensile Response section as suggested by the reviewer. Thanks. Lines 228-230 provide a brief explanation on the reason for crystallinity of the ECM processed samples. This has to do with the blended virgin PP to the PP-GF recyclate.

• How is the mechanical properties for the as-received materials? In addition, the mechanical properties of the as-received materials should compared with the as-processed mterials.

Figures 8 (Tensile), 15 (Flexure), 18 (Impact) in fact provide this data already. The 100% recycle on the x-axis in these figures represents the as-received material. We have added this note to the figure caption in case of any confusion.

• The format of from table 3 to figure 13 should be revised.

We were not fully clear what the reviewer wanted here. We checked the order of Table 3 which provides full summary of the tensile data, then Figures 10-13 discuss the failure modes and evidence of fiber orientation etc. So we have not made any changes, since we see this as a logical representation.

 

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear Authors,

you have addressed the comments, and answered the questions. The revised version of your manuscript appears to be suitable for publication.

Reviewer 2 Report

All of the issues mentioned were resolved in detail.