Synthesis of an Epoxy Toughening Curing Agent through Modification of Terephthalic Acid Sludge Waste

Round 1

Reviewer 1 Report

The authors used 1,6-hexanediol to modify PTA sludge waste for the preparation of epoxy toughening curing agents.
We suggest the following comments for the improvement of the manuscript:

1) Figures 1 and 3 can be a big larger

2) In Figure 2, the text is too small to read, perhaps increase its size and make it bold

3) Table 1, place the note next to the caption of the table

4)  The abstract lacks the appeal needed to captivate readers' interest.

5)  It fails to succinctly summarize the significance and key findings, which is crucial for attracting potential readers.

6) Upon reviewing the full manuscript, I found that it did not sufficiently address the impacts of 1,6-hexanediol. This omission significantly detracts from the overall quality and impact of the research.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The work is devoted to the development of a novel epoxy toughening curing agent through the treatment of PTA sludge waste. The topic is relevant since terephthalic acid (TA) is a widely used chemical raw material. The agent obtained during processing was used to create a number of test samples, which were examined by a number of instrumental methods. The results show that the toughness of the resulting epoxy resin is significantly enhanced, making the method interesting for further development and implementation.

The manuscript is well structured and formatted, however, it cannot be recommended for publication in its current form. Comments are below:

1. Line 117. It is obvious that the two proposals directly contradict each other: “However, the isocyanate (-NCO) is highly reactive, making it unsuitable for direct use and storage. Thus, the storage time of the curing agent is prolonged, and the reaction process becomes controllable”. Perhaps the second relates to imidazole as a curing agent?
2. Perhaps it is worth indicating not only the wave numbers in Figure 1, but also the corresponding functional groups, which are described in the text? This will make the content easier for the reader to understand. The same applies to Figure 3.
3. Figure 2 is not explained in any way in the text; it is simply indicated that this is a flow chart of PTA sludge modification.
4. Line 145. “On the basis of the curing process described in Scheme 1”. The manuscript does not contain Scheme 1, so what are the authors referring to?
5. Line 155. This reference to Table 1 is meaningless because a description of the properties is given after the first mention of Table 1 in the paragraph above.
6. Line 158. The authors write: “The control group was cured with a commercial amine curing agent”. The reviewer did not find the manufacturer and brand of agent indicated, and this may be critical to reproducing the experiment.
7. It may make sense to compare the properties of the obtained samples not only with an unspecified brand of commercial origin (see p.6), but also with samples of resins obtained by other scientific groups when processing PTA sludge.

Moderate editing of English language required

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Research on should be dropped in the title.

Lines 15,16.  (Contaminated?) TA generates…purified terephthalic acid (PTA). The reader will say, “Excellent, we get pure TA.” Something is wrong with the logic.

Line 30. The acronym “t” stands probably for “tonne”. Not obvious to the reader.

The authors should present one to two chemical reactions which they studied.

Many numerical values presented with a high accuracy, but no determination errors.

Hard to understand the main goal of the work. Is it an attempt to convert sludge into something useful?

Line 44. Nucleophilic reaction. That is a doubtful statement.

Line 68. The correct name: 4,4'-methylenediphenyl diisocyanate (MDI)

Comments for author File: Comments.pdf

Difficult to understand the logic. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I believe the manuscript could be accepted in its present form