Reactive Extrusion Grafting of Glycidyl Methacrylate onto Low-Density and Recycled Polyethylene Using Supercritical Carbon Dioxide

Round 1

Reviewer 1 Report

The manuscript describes the use of supercritical carbon-dioxide in the grafting of glycidyl methacrylate over the LDPE and recycled LDPE through reactive extrusion process. The approach is not novel and has been tested for polyolefin in the literature. The claimed results are interesting, however, need further clarifications for better understanding and improvement of this research article. Authors are kindly requested to answer following questions and include suggestions, if found appropriate: 

1. The manuscript English and scientific soundness may be improved. For instance, on page 5 Line 201 the spelling of strength is incorrect. In Line 197 the units of surface area is wrong. On page 12, Figure 51, the right side image y-axis title should be stress at break, not strain at break. Such mistakes makes it very hard to go through the article, kindly improve.
2. Please unify the Figure numbers in a particular order. After Figure 9 the Figure number is 40 and then Figure 51. However, in text the Figures are mentioned as Figure 10 and 11 respectively. Please correct it. 
3. In conclusions, line 400, the sentence: "However, the increase for recycled LPDE is less pronounced." First of all, it should be LDPE and secondly the meaning of sentence in incomplete in it's own. It may be better to include word "tensile properties increase" or the most appropriate phrase.
4. In the results and discussion section on page 5, the explanation of the reaction mechanism needs appropriate references for the claimed phenomenon or add evidence for the same. 
5. Please add the standard deviation for Figure 5.  
6. On page 8, authors claim that the viscosity of the RPE was 6 times higher to that of the LDPE at 130 C. (a) Why RPE has so high viscosity? (b) Is it due to some additional unknown fillers in RPE or presence of other polyolefin such as PP or may be RPE molecular weight and molecular weight distribution is higher than the LDPE? Kindly explain.
7. The influence of temperature on FD% is marginal in the presence of CO2 and largely narrowing down to the similar values. (a) Why is it so? (b) Why FD% drops at 180 C compared to 175 C for almost all the runs?
8. On page 10, Figure 7 discussion, authors mention that (329-330)> "....the scCO2 could have swollen the polymer more due to the higher viscosity at higher temperatures." Please explain the relation for increase in viscosity with temperature in the case of LDPE. 
9. In Figure 51 (on page 12), the standard deviation (or error range) is too large to be accepted. please explain the reason(s) behind these large errors. For instance, in Figure 51 for strain at break with FD% 1,2 error bar is almost +/- 100%.
10. In Figure 2 on page 13, the LDPE image is quite blur and need refocused and clear image. Kindly incorporate. The LDPE image does show inhomogeneity and therefore cannot be considered that the LDPE is free of particles with the current blurred image. 

Author Response

pleas see attached file

Author Response File: Author Response.docx

Reviewer 2 Report

In this paper, the authors documents and discusses research work associated with A Multimodal Improved Particle Swarm Optimization for High Dimensional Problems in Electromagnetic Devices.

1. The first appearance of LDPE and RPE have no full name to explain it in the abstract.
2. Figure 1 is not clear, please put an enlarged illustration.
3. Whether the content of scCO2 has an influence on the grafting degree?
4. The conclusion is too short and must be improved, highlighting the purpose of the paper, summarizing the methods used and the results achieved.
5. There are some grammar and word mistakes in the manuscript. Please go through the manuscript carefully again.

Author Response

please see attached file

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Authors have made an attempt to answer the questions of the reviewers in the revised manuscript. The manuscript has been improved compared to the first version. However, the provided answer for the questions and the improvement in the manuscript is insufficient and not satisfactory in terms of research novelty and design. The research novelty may be improved by answering the questions being left for the future research in the conclusions section. 

Furthermore, the provided manuscript possess comments in language other than English, which were not understood. In the current format, I recommend to reject the manuscript. 

Author Response

see attached file

Author Response File: Author Response.docx

Reviewer 2 Report

Can be accepted now.

Author Response

Se would like to thank the reviewer for the comments that certainly contributed to improve the manuscript

Round 3

Reviewer 1 Report

Authors have answered the concerns of the reviewer.