Thermal Behavior of Biodegradable Compositions of Polylactide and Poly(3-hydroxybutyrate) with Chitosan and the Effect of UV Radiation on Their Structure
, Sergey Usachev 1, Anastasia Yakhina 1, Lubov Zhorina 1 and Alexander Berlin 1
Round 1
Reviewer 1 Report
The authors present a series of observed data on the thermal stability of PLA and PHB, either alone or mixed with chitosan, as well as thir degradation against UV-irradiation.
As it appears the present report is not the only one devoted to the investigations on the studied polymers. The previously published reports of the autors on the subject were cited in Introduction (refs 13-15). However, it would be appreciable if the authors could mention by a few words whether the presented results are new or rather an overview of the published data.
Although the thermal stability analysis of the polymers and their related mixtures seems to be quite clear, I have some concerns about the UV-degradation study of PLA and PHB, analyzed alone as described in the text.
In fact, the FT-IR spectra displayed in Figs. 5 and 6 do not reflect as it should the descriptions given in Pages 8-10 on the band shifts and intensity changes caused by UV-irraditaion. It would be better to transfer these spectra (displayed mainly in the whole middle wavenumber region to Supplementary Information, and keep as more expanded Figures, reinforced by band decomposition, related basically to the specific regions where the changes due to the ester bond breakdown and OH formation.
I think that this is the only way to reinforce the chemical pathway suggested in Fig. 7a&b related to the UV-degradatation of the used chemical products. Obviously, in the future presentation, the observed FT-IR band decompositon can only be restricted to the main components observed in the spectra displayed in Figs. 5 and 6.
A Table, mentioning the tentative assignments of the observed bands, would also be helpful, in order to better understand the discussion on the key IR markers related to chemical degradation.
Author Response
Dear reviewer!
Thank you for attentive reading of our manuscript and made comments.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Binary compositions based on PLA and PHB were prepared in liquid phase, and the sorption capacity to iron ions was investigated. Comprehensive characterizations and detailed analyses were implemented. In my opinion, I agree with the publication of this manuscript in Journal of Applied Sciences, just before, please clarify few doubts and made minor revisions given as following:
1. The scientific or social significance of this research should be mentioned in Abstract section.
2. In the section of “Introduction”，more statements are suggested to be added to clarify the recent research status and research difficulties of iron ion adsorption by biodegradable composite materials.
3. If the presence of iron ions will affect the thermal degradation behavior of PLA and PHB? Why?
4. The statements “approximately on 20 %” in line 176 is not consistent with the data shown in table 2. Please check.
5. In Table 3, please check if the Ton, Tmax, ΔHd values of sample PHB and sample “PHB-chitosan (50:50) Fe3+ absorbed” are exactly same?
6. At the bottom of page 7 (Line 210~212), the authors wrote “…..increase in the values of Tmax and ΔHd for PHB-chitosan (268 °C and -700 J/g) in comparison with (278 °C and -1214 J/g) for PHB-chitosan composition with sorbed Fe3+ ions”. I can’t find related information in Table 2. Please check.
Author Response
Dear reviewer!
Thank you for attentive reading of our manuscript and made comments.
Author Response File: Author Response.docx
Reviewer 3 Report
My general evaluation for the article titled “Thermal behavior of biodegradable compositions of polylactide 2 and poly(3-hydroxybutyrate) with chitosan and the effect of UV 3 radiation on their structure” is as follows. It is believed that the following corrections will be beneficial for the strengthening of the article.
1. The abstract section should be rearranged. Summary section is too short. Important details about the study should be given. In addition, the numerical results obtained as a result of the study should be given.
2. The literature section remained weak. If there are more current literature studies, these should be examined in detail and added to the literature section. It is a suggestion for the literature part of the article to be more comprehensive. It may be useful to include relevant articles in 2020-2023 in references.
3. The main properties of the material used in Section 2 can be given in Table form.
4. In Section 3 the results of the study are well explained. Only the discussion section should be viewed as a separate topic.
5. Will the study continue to be developed? If yes, explanations about future studies should be added in the conclusion section.
Author Response
Dear reviewer!
Thank you for attentive reading of our manuscript and made comments.
Author Response File: Author Response.docx
Reviewer 4 Report
Reviewer comments regarding and decision: “Thermal behavior of biodegradable compositions of polylactide 2 and poly(3-hydroxybutyrate) with chitosan and the effect of UV 3 radiation on their structure”
1. The Abstract must be seriously improved and developed! It is much too short and generally described, only in theoretical meaning way! The authors do not describe the most important experimental stages and results, neither the most significant conclusions derived from this study! The abstract needs serious improvements! In the abstract, authors must clearly describe the most significant and important results of the experimental completed stages and the most important conclusions!
2. The section named “3.1. The comparison of sorption capacity of PHB-chitosan and PLA-chitosan compositions” from RESULTS AND DISCUSSION PARAGRAPH must be improved and developed!! How did the authors calculate “Concentration of sorbed Fe3+ ions (wt.%) by film compositions PHB-chitosan (50:50) wt.% 105 and PLA-chitosan (50:50) wt.%” related in Table 1 from page 3 of the manuscript? Authors must describe in much more details this aspect!! They must give a math formula for this method: “Concentration of sorbed Fe3+ ions (wt.%) by film compositions PHB-chitosan (50:50) wt.% 105 and PLA-chitosan (50:50) wt.%”” and to insert the raw data tables of these concentrations and the calculation procedure. I suggest the authors to also design a conclusive graph, to show and to discuss clearly this interrelationship!!
2.1. To be more suggestive and conclusive, I advise the authors to conduct and to add also a complete “Scanning Electron Microscopy High-Resolution Analysis (SEM)” and to insert the images in the manuscript text, followed by detailed and concrete interpretations of this images, as a comparative study between samples before UV irradiation and after UV-Irradiation, at different times! The authors could also add representative and clear graphs that reflect this study! It would be a strong point of this research, about my opinion!
3. A statistical study is mandatory to be conducted (like ANOVA TESTS, t-student tests), for validating the most conclusive obtained experimental results! The essential results of this statistical study must be clearly discussed and the most conclusive of them must be inserted in Conclusions paragraph! I suggest the authors Statistical analysis should be conducted in relation to the following essential paragraph: “3.3. Investigation of the UV radiation action on polyesters PHB and PLA by a method of IR 219 spectroscopy”, to reflect indeed the final structural modification under UV radiations action!
4. Bibliographical references must be completely removed from the RESULTS AND DISCUSSIONS section! RESULTS AND DISCUSSIONS must describe only the original obtained results and discuss only the experimental, original work of the authors, only the experimental data obtained during the experimental stages!! Bibliographic references should only be inserted in the general part of the Introduction, possibly also in Materials and Methods section!!
5. Conclusions are very short and without any significance, without any substance, generally described! Conclusions must be totally reconsidered because are poorly represented in the last paragraph of this paper, too general, very short and superficially treated and does not suggest at all the main final obtained results, neither the most important experimental findings!! In Conclusions section, the authors must clearly describe the most relevant experimental stages and the most important experimental results obtained! From the conclusions paragraph it should be very clear whether the authors have achieved their proposed goal and the experimental objectives described at the beginning of this paper! I encourage the authors to make all these corrections! Thank you very much!!
Author Response
Dear reviewer!
Thank you for attentive reading of our manuscript and made comments.
Author Response File: Author Response.docx
Reviewer 5 Report
Rogovina and coworkers present an interesting study of the thermal properties of compositions of PLA-Chitosan or PHB- chitosan and evaluate the effect of UV irradiation on them. I would recommend this paper for publications after discussing the following questions:
1) Did you vary the relative of concentrations of PLA, PHB and chitosan and studied the thermal and UV irradiation behavior with these differences.
2) Could you use NMR to study the UV irradiation effects on the compositions.
Author Response
Dear reviewer!
Thank you for attentive reading of our manuscript and made comments.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
No suggestion for this revised manuscript.
Author Response
We would like to draw your attention that unlike the first review, this review does not contain any comments, but there is a mark in the section “I would not like to sign my review report” (In the first review was “I would like to sign my review report”). Could this be a typo?
Reviewer 4 Report
1. Please improve the abstract! The abstract is still very superficial made, very general addressed!! The authors do not describe the most important experimental stages and results, neither the most significant conclusions derived from this study! The abstract needs serious improvements! In the abstract, authors must clearly describe the most significant and important results of the experimental completed stages (with numerical values and calculated parameters) and the most important experimental conclusions derived from this study!
2. The bibliographical references must be completely removed from the "RESULTS AND DISCUSSION" paragraph! " RESULTS AND DISCUSSIONS" must describe only the experimental, original results of the authors, only the necessary comments regarding experimental data values obtained!! Bibliographical references should only be inserted in the general part of the "Introduction", possibly also in "Materials and methods" section! More clarity, please! In "DISCUSSIONS" paragraph, the authors must describe only their own experimental results obtained! Authors must discuss, interpret and compare all the working methods applied and the essential experimental results obtained!
3. Please insert in the manuscript all “Statistical analysis of FTIR data” paragraph from the supplementary files material, which are very well done, very good!! Congratulations! Two tables with statistical values for ANOVA (ONE WAY and the corresponding graphs with all the discussions and comments written there!! Are very well done! This statistical analysis is mandatory and must be inserted in the final part of “RESULTS” section!
3.1. Please, insert in the manuscript the mathematical formula and all the tables containing individual raw data values which are the basis of the results rendered in: “Table 1. Concentration of sorbed Fe3+ ions (wt. %) by film compositions PHB-chitosan (50:50) wt. 163 % and PLA-chitosan (50:50) wt. %”.How did you calculate the Concentration of sorbed Fe3+ ions (wt. %)? All the values are needed to be inserted!
4. Please, insert in the manuscript all the tables containing individual raw data values which are the basis of the results rendered in: “Table 2. DSC parameters of thermal transitions observed in PLA, PHB and their compositions with 220 chitosan” containing individual enthalpy values and the degree of crystallinity, c% calculation for each sample analyzed!
5. Insert in the manuscript the mathematical formula and all the tables containing individual raw data values which are the basis of the results rendered in: “Table 3. Thermal stability characteristics of PLA and PHB and their compositions with chitosan”. How did you calculate the “ΔHd”, enthalpy J/g from Table 3? All the values are needed to be inserted! In the supplementary files I did not found !
6. “Conclusions” are still general made in some parts! Please insert in the “Conclusions” paragraph the most significant and the most important vales (numerical values, specific parameters) obtained during the most important experimental stages! The authors must clearly describe the most relevant experimental stages and the most important experimental results obtained! From the conclusions paragraph, it should be very clear whether the authors have achieved their proposed goal and the experimental objectives related to the beginning of this paper. Thank you very much!! I encourage the authors to make all the corrections mentioned above! I congratulate them for the effort and for their very interesting work!
Author Response
Dear reviewer!
Thank you for attentive reading of our manuscript and made comments. The necessary corrections in the text were made.
Author Response File: Author Response.docx
Round 3
Reviewer 4 Report
MDPI-Applied Sciences (ISSN 2076-3417):
Reviewer Comments and Final Decision for the article entitled: „Thermal behavior of biodegradable compositions of polylactide and poly(3-hydroxybutyrate) with chitosan and the effect of UV radiation on their structure”
The subject approached is very interesting and I congratulate the authors for their work and effort
1. The bibliographical references must be completely removed from the "RESULTS AND DISCUSSIONS" paragraph! "RESULTS AND DISCUSSIONS" must describe only the own experimental, original results of the authors, only the necessary comments regarding experimental data values obtained!! Bibliographical references should only be inserted in the general part of the "Introduction", possibly also in "Materials and methods" section! In "DISCUSSIONS" paragraph, the authors must describe only their own experimental results obtained, according to their applied methods! They must discuss, interpret and compare all the working methods applied and the essential experimental results obtained at the end of the work! Statistical study was very short and very superficial discussed!
2. Please insert in the “Conclusions” paragraph some experimental numerical values and some significant and conclusive parameters values, which should clearly illustrate the final conclusions obtained!!
My final decision is " Accept after minor revision (corrections to minor methodological errors and text editing)"! Thank you very much!! The subject is very interesting and I encourage the authors to correct only two aspects mentioned above! Congratulations!! Thank you very much!!
Author Response
Dear reviewer!
Thank you once more for your remarks.
Author Response File: Author Response.docx
