Synthesis and Application of a Low Dye Absorption Waterborne Polyurethane for Microfiber Synthetic Leather
Round 1
Reviewer 1 Report
The manuscript by Luo and co-workers deals with the synthesis of water-bone polyurethanes and their application to modulate the dye absorption of synthetic fibers.
The manuscript is worth of publishing but some point should be addressed:
i) the manuscript is extremely and unnecessarily long; a lot of information could be transferred to a supporting information file and this will improve the readability of the manuscript itself (e.g. section 3.6 and begin of 3.7);
ii) References are quite out of date failing in giving a clear overview of the most recent development for PUs (PUs for energy: 10.1002/adfm.201809129; 10.1021/acsami.0c17652 or as coatings for antifoling 10.1016/j.porgcoat.2021.106405 or wear resistance 10.1007/s42114-021-00206-3) ad more specifically in leather treatment (10.1080/1023666X.2021.2006906);
iii) In line 50-53 authors stated that the use of water will improve the greenness of the process; yet, it also partially true once the energy for waste water treatment is considered. Please comment of that;
iv) Characterization of materials is relatively complete but the discussion should be more carefully conduced. This is expecially related to the statistical analyses of some data. For example, Tg values (both for hard and soft segments) are practically undistinguishable one from the other considering the indetermination in the detection of Tg values. So the related discussion should be modified;
v) Similarly to point iv) is the analyses of the alkali reduction ratio (ranging from 32.01 and 33.27) without a clear trend. A statistical analyses is required to prove that the reported values (and differences!) have a statistical validity;
vi) Caption of table 13 should be amended;
vii) The approach used by the authors to calculate the decoloration rate is not clear and should be better explained. Additionally, it should be better to normalize the decoloration rate for the dye concentration/amount because it is obvious that the higher the concentration of the colorant in the dyeing solution, the higher the amount of fisisorbed/entrapped dye, the higher the decoloration ratio. Indeed, the higher amount of dye is removed just after the first washing.
Author Response
Response to Reviewer Comments
Dear Reviewer,
We would like to thank you for your efforts in reviewing our manuscript titled " Synthesis and Application of a Low Dye Absorption Waterborne Polyurethane Using for Microfiber Synthetic Leather". I really appreciate all your comments. Please find my itemized responses in below and my revisions in the re-submitted files.
Point 1: the manuscript is extremely and unnecessarily long; a lot of information could be transferred to a supporting information file and this will improve the readability of the manuscript itself (e.g. section 3.6 and begin of 3.7);
Response 1: Thank you very much for your advice, total of section 3.6 and the standard curve for disperse red S-5BL in section 3.7 were transferred to a supplementary material in purpose of making the article more compact and readable.
Point 2: References are quite out of date failing in giving a clear overview of the most recent development for PUs (PUs for energy: 10.1002/adfm.201809129; 10.1021/acsami.0c17652 or as coatings for antifoling 10.1016/j.porgcoat.2021.106405 or wear resistance 10.1007/s42114-021-00206-3) ad more specifically in leather treatment (10.1080/1023666X.2021.2006906);
Response 2: Thank you for your positive comments, the most recent develoment for PUs and some research progress for leather finishing was added into the introduction section with related references.
Point 3: In line 50-53 authors stated that the use of water will improve the greenness of the process; yet, it also partially true once the energy for waste water treatment is considered. Please comment of that;
Response 3: Thank you for your constructive comment, waterborne polyurethane is a new type of polyurethane system in which water is used instead of organic solvent as a dispersion medium. Traditional solvent-based polyurethane usually uses a large amount of acetone or butanone as the dispersion medium, and its cost is much higher than that of pure water, which leads to the cost of solvent-based polyurethane in the production process is much higher than that of water-based polyurethane. In terms of the cost of wastewater treatment, the waste water generated during the synthesis of solvent-based polyurethane contains a large amount of organic solvents, so the steps such as separation of organic solvents and environmental protection treatment for waster water will lead to a significant increase in cost. In other words, it is much easier to treat the same volume of waste water produced by the waterborne polyurethane synthesis process because of lower contain of organic solvent.
Part of the statement above had been added to the introduction section.
Point 4: Characterization of materials is relatively complete but the discussion should be more carefully conduced. This is expecially related to the statistical analyses of some data. For example, Tg values (both for hard and soft segments) are practically undistinguishable one from the other considering the indetermination in the detection of Tg values. So the related discussion should be modified;
Response 4: Thank you very much for your valuable comments, the reason for the insignificant change trend of Tg results is that the content of hard segment in all experimental groups was controlled at 35%, and the ratio of hard segment and soft segment was relatively fixed (by adding 1,4-Butanediol). Adding HTPB will only change the degree of microphase separation between soft and hard segments without affecting the ratio of hard segments. In order to clearly show the degree of change in microphase separation, the Tg difference (δTg) between soft and hard segments is introduced into Table 5 from section 3.4.
Point 5: Similarly to point iv) is the analyses of the alkali reduction ratio (ranging from 32.01 and 33.27) without a clear trend. A statistical analyses is required to prove that the reported values (and differences!) have a statistical validity;
Response 5: Thank you for your insightful comment, to prove the alkali reduction ratio values have a statistical validity, the data previously done are stated in the supplementary material file. According to the results of the t-test between the groups, the one-tailed p values are all less than 0.05, so it is reasonable to indicate that there is a significant difference for alkali reduction ration between the leather samples.
Point 6&7: Caption of table 13 should be amended; The approach used by the authors to calculate the decoloration rate is not clear and should be better explained. Additionally, it should be better to normalize the decoloration rate for the dye concentration/amount because it is obvious that the higher the concentration of the colorant in the dyeing solution, the higher the amount of fisisorbed/entrapped dye, the higher the decoloration ratio. Indeed, the higher amount of dye is removed just after the first washing.
Response 6&7: Thank you again for your constructive comments, in order to describe the decoloration rate more clearly, the concept of decoloration rate is introduced and a clear definition is given. The decoloration rate means the difference in the concentration of the dye solution between the first and the third washing, higher decoloration rate indicates that more floating dye can be eluted through the first wash step rather than subsequent wash steps, thus the corresponding wash efficiency is higher.
Here are all my response to your comments. Thank you again for your valuable comments and suggestions. I am looking forward to hearing from you soon in due course.
Reviewer 2 Report
Abstract:
Lines 10-12: this sentence is not in line with the way you receive WPU at work - please provide more details! What does IPDI mean is "urethane linkage"? - this is a factual error! Please correct it!
Line 14: "tensile test" - where in the work the authors present the results of the research on mechanical properties?
"thermal test" - change to "thermal properties"
Introduction
Lines 45-46: the sentence is incorrect - please correct it
Materials and Methods
Line 73: Poly propylene glycol: please indicate the name as recommended by IUPAC
Line 76: hydroxyl - We start each sentence with a capital letter, HTPB: give the abbreviation for the first time in the Introduction
Line 77: a space before the parenthesis
Line 79: Ethylene diamine (EDA) - please standardize the name of this compound (see line 47)
Lines 82-83: the sentence is incorrectly written - please correct it !!!
N220: what is this? Please provide the name of the compound in section 2.1. Materials!
Lines 111, 121: CH3COOH - correct the pattern
Line 118: Drawing caption in capital letters!
Line 120: (owf) - extend the record
line 122: 212BA: provide the chemical name
Line 145: "Thermo Charaterization" change into "Thermal Characterization"
3.2. FTIR Spectrum
How did the authors prove that DMPA is incorporated into the polymer chain? Please provide the appropriate absorption bands!
Why were the free -COOH groups not marked? This is a prerequisite for the calculation of the amount of TEA used for neutralization!
Line 206: remove spaces in the variation names of HTPB structures!
3.4. Thermal properties
Please in section 2.5.4. describe in detail the conditions for conducting DSC analysis. Why was only one heating done? For new polymers, 2 heating cycles should be performed as the first cycle is responsible for the thermal history of the sample resulting from the synthesis and may falsify the results!
TG analysis: in section 2.5.4 specify the analysis conditions!
Table 6: Specify the temperatures with an accuracy of 1 ° C!
Lines 259-267: the analysis is the authors' conjecture! Please refer in your considerations to the available literature describing the results of the TG analysis of similar materials !!
Lines 274-275: improve units
Line 279: We start each sentence with a capital letter
Additionally:
Tensile test: please describe as it is not in the text and the abstract suggests that mechanical properties tests have been done !!
Compare the results of your research even more with the results of other authors !!
Correct Punctuation and English (Native Speaker!).
Author Response
Response to Reviewer Comments
Dear Reviewer,
We really appreciate you for your carefulness and conscientiousness. Your suggestions are really valuable and helpful for revising and improving our paper. According to your suggestions, we have made the following revisions on this manuscript, Please find my itemized responses in below and my revisions in the re-submitted files.
Point 1: Comments for abstract: Lines 10-12: this sentence is not in line with the way you receive WPU at work - please provide more details! What does IPDI mean is "urethane linkage"? - this is a factual error! Please correct it!
Line 14: "tensile test" - where in the work the authors present the results of the research on mechanical properties?
"thermal test" - change to "thermal properties"
Response 1: Thank you very much for your advices. The sentence from lines 10-12 has been corrected. For tensile test, I feel sorry that I forgot to add the mechanics experiment because of my carelessness, now this part has been added to the article as section 3.5. And for “thermal test” appearing in abstract, has been changed to "thermal properties".
Point 2: Lines 45-46: the sentence is incorrect - please correct it
Response 2: Thank you for your constructive comment, the sentence has been corrected.
Point 3: Some format modification of Materials and Methods section:
Line 73: Poly propylene glycol: please indicate the name as recommended by IUPAC
Line 76: hydroxyl - We start each sentence with a capital letter, HTPB: give the abbreviation for the first time in the Introduction
Line 77: a space before the parenthesis
Line 79: Ethylene diamine (EDA) - please standardize the name of this compound (see line 47)
Lines 82-83: the sentence is incorrectly written - please correct it !!!
Lines 111, 121: CH3COOH - correct the pattern
Line 118: Drawing caption in capital letters!
Line 120: (owf) - extend the record
line 122: 212BA: provide the chemical name
Line 145: "Thermo Charaterization" change into "Thermal Characterization"
Response 3: Thank you for your advices, all the incorrect formats has been revised except the chemical name about leveling agent 212BA, that is a high temperature leveling agent developed by Transfar Zhilian Co.,Ltd. We wish to apologize that we can not get the specific formula and the preparation conditions of this leveling agent.
Point 4: N220: what is this? Please provide the name of the compound in section 2.1. Materials!
Response 4: Thank you for your positive comments, the N220 means Poly(1,2-Propanediol) with number molecular weight of 2000
Point 5: 3.2. FTIR Spectrum
How did the authors prove that DMPA is incorporated into the polymer chain? Please provide the appropriate absorption bands!
Why were the free -COOH groups not marked? This is a prerequisite for the calculation of the amount of TEA used for neutralization!
Line 206 remove spaces in the variation names of HTPB structures!
Response 5: Thank you very much for your valuable comments, to prove that DMPA was successfully synthesized into the polymer chain, the characteristic absorption peak of triethylamine carboxylate at 1461cm-1 were marked in the FTIR spectrum according to the reference 28(10.1016/j.ijadhadh.2005.02.002).
In order to calculate the amount of TEA used for neutralization, the amount of DMPA shoud be calculated. The amount of DMPA used for synthesising WPUs in this article has been controlled at 4% of total system, the molar ratio of DMPA and TEA is 1:1, thus the amount of TEA can be calculated.
Point 6: 3.4. Thermal properties
Please in section 2.5.4. describe in detail the conditions for conducting DSC analysis. Why was only one heating done? For new polymers, 2 heating cycles should be performed as the first cycle is responsible for the thermal history of the sample resulting from the synthesis and may falsify the results!
Response 6: Thank you for your insightful comment, we have detailed the conditions for DSC in section 2.5.4. Start from room temperature, heat up to 150℃ at a rate of 10K/min and hold for 5 minutes, then cool down to -100℃ at a rate of 10K/min and hold at -100℃ for 5 minutes, finally heat up to 150℃ from -100℃ to complete the test.
Point 7: TG analysis: in section 2.5.4 specify the analysis conditions!
Table 6: Specify the temperatures with an accuracy of 1 °C!
Lines 259-267: the analysis is the authors' conjecture! Please refer in your considerations to the available literature describing the results of the TG analysis of similar materials !!
Lines 274-275: improve units
Line 279: We start each sentence with a capital letter
Response 7: Thank you for your constructive comments, conditions for TG experiment has been added to section 2.5.4 and TG analysis now has literature to support. Some units with wrong format has been corrected
Point 8: Additionally:
Tensile test: please describe as it is not in the text and the abstract suggests that mechanical properties tests have been done !!
Compare the results of your research even more with the results of other authors !!
Correct Punctuation and English (Native Speaker!).
Response 8: Thank you very much for your valuable comments, a tensile test has been added to the article as section 3.5. We have reviewed the punctuation and grammar of the full article and the full text has been repeatedly reviewed by a native English speaker.
Here are all my response to your comments. Thank you again for your valuable comments and suggestions. I am looking forward to hearing from you soon in due course.
Round 2
Reviewer 1 Report
Authors properly replied to all the comments raised by the referees. The manuscript could be accepted for publication.
I would like to lay down just a small comment, hoping this would be interesting suggestion for the authors:
with respect to the discussion on the sustainability, one should considered not only the costs but also other parameters as the substitutionability of a given material/solvent used in a process. For example, it is true that acetone is not a green solvent but it is also true that the higher amount of acetone is obtained as a byproduct of the phenol production. The industrial processes based on acetone are thus quite interesting to transform a waste in a resource
Reviewer 2 Report
The text has been significantly improved. Accept
