Kinetic Analysis on the Stabilization Effects of Substituted POSS Powders Embedded in γ-Radiolyzed Polypropylene

Round 1

Reviewer 1 Report

This manuscript was previously reported as “Kinetic Analysis on the Stabilization Effects of Substituted POSS Powders Embedded in γ-Radiolyzed Polypropylene”. The authors resubmitted as “Kinetic analysis on the stabilization effects of substituted POSS powders embedded in γ-radiolyzed polypropylene”. There is no significant difference between the previously reported and resubmitted manuscript. The study is of reasonable quality, although it is not particularly novel. The work is well written, however, the references style and overall presentation are not proper. The authors need to improve the overall presentation as well as reference style according to manuscript template requirements. It is better to be more specific in the Abstract with proper key results.

Author Response

Dear reviewer,

I am glad that your decision is clear: our manuscript can be passed for publication. We appreciate this option very much.

Many thanks,

Prof. Traian Zaharescu

Reviewer 2 Report

This manuscript I received for the second time. The previous submission had a number jcs 1161573. I cant see again the changes that I asked previously

1. Improve signal to noise ratio for ftir(use more than 50 scans)
2. Make a try for XPS analysis
3. Use area below the peaks and not their intensity. You have to do integration!

Author Response

Dear reviewer,

We appreciate very much your rigor that demonstrates your high expertise in the field. Finally, we substituted the wave length of reference.

Other comments are added demonstrating the support for your further decision. We hope that these comments will determine you to accept our manuscript for publication. It will be a good opportunity for us to spread our results according with the editing ethics.

We send to you our thanks for the efforts spent in the upgrading the quality of our manuscript.

Prof. Traian Zaharescu

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Authors answered to my comments.

Author Response

Thanks for your comments

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This manuscript reports the Kinetic Analysis on the Stabilization Effects of Substituted POSS Powders Embedded in γ-Radiolyzed Polypropylene. The author needs to carefully investigate and discuss the following issue:

1. What is the novelty of this manuscript? The authors should discuss the novelty clearly in the introduction part.
2. Need to add some advantages of this technique compared to the previous study.
3. Needs to add some references in the discussion of Fig. 10.
4. The author should explain with relevant references (i) why 100 kGy irradiation is effective to compare to other irradiation and (ii) why sample P3 is most effective compare to other samples in Fig.11.

Author Response

Referee # 1

1. What is the novelty of this manuscript? The authors should discuss the novelty clearly in the introduction part.

The role of fillers in polymer formulation is undoubtfully demonstrated. Their contribution to the extension of product durability may be ascribed either to the efficient interference in the degradation mechanism by the free radical scavenging (POSS powders: T. Zaharescu, I. Blanco, F. A. Bottino (2020). Surface antioxidant activity of modified particles in POSS/EPDM Hybrids. Appl. Surf. Sci., 509, 144702) or by the delay of oxidation (HaP: T. Zaharescu, C. Tardei, V. Marinescu, M. Râpă, M. Iordoc (2020). Interphase surface effects on the thermal stability of hydroxyapatite/poly(lactic acid) hybrids. Ceramics Int., 46, 7288-7297; oxides: T. Zaharescu (2019). Stabilization effects of EPDM by doped inorganic filler for space and terrestrial applications. Mater Chem Phys., 234, 102-109). The inorganic phase might be judged as a barrier for oxygen diffusion and the blocking agent for the oxidation of free radicals. The novelties of a publishing manuscript are formally related to the compositional solution and the qualification of durability.

The evaluation of new polymer compositions destined to the manufacture of resistant packaging materials, commodities, toys, medical wear, sealant gaskets and so on does not only concern the innovation of inspired consistency, but also the optimization of proposed compositions. Taking into account previously published results, the new proposals of foreseen products must show some detectable features: new configurations, high acting efficiency, extended areas of materials, relevance and applicability. This paper intends to describe the improvement contribution of new POSS structures that would be suitable for the diminution of degradation effects during the intensive ageing of polymers. The former steps were already done with simplified configurations of POSS (T. Zaharescu, K. Pielikowski (2016). Stabilization effects of POSS nanoparticles on gamma-irradiated polyurethane. J. Therm. Anal. Calorim. 124, 767-774; T. Zaharescu (2019). Radiation processing analysis of aged EPDM/vinyl-POSS hybrid systems. J. Therm. Anal. Calorim., 138, 2367-2374; T. Zaharescu, M. Catauro, I. Blanco (2021). Kinetics of the non-isothermal degradation of POSS/EPDM hybrids compounds. Macromol. Symp., 395, 2000221).

The added text for highlighing novelty is placed at the end of Introduction: The novelties of this study are based on the optimisation of stability improvement by new structured fillers for a largely implemented polyolefin namely polypropylene, the new suggestions POSS structures available for commercial areas, the interpretation of stabilization effects involving the new proposed POSS configurations.

2. Need to add some advantages of this technique compared to the previous study.

The selection of chemiluminescence as a suitable characterization procedure was demonstrated by several previous papers (T. Zaharescu, C. Mateescu, M. Mariş (2021). The chemiluminescence study on the radiochemical stability of polypropylene stabilized with microalgal extracts. Radiat. Phys. Chem., 183, 109401; T. Zaharescu, T. Borbath, I. Blanco, I. Borbath (2021). Stability effect of metallic traces in the degradation of extension of materials.

Macromol. Symp., 395, 2000224; T. Zaharescu, Y. X. Chou, E. Hebda, K. Raftopoulos, K. Pielikowski (2021). Complementary assessment of g-irradiated polyurethane-POSS hybrids by chemiluminescence and differential scanning calorimetry. Polym. Testing., 96, 107117; T. Zaharescu, M. Râpă, I. Blanco, T. Borbath, I. Borbath (2020). Durability of UHMWPE/HDPE composites under accelerated degradation. Polymers, 12, 1241 and many, many other published papers along more than 20 years). This method of chemiluminescente is seldom an investigation option, because the are not many decives available in the world.

The added fragments for the improvement of information level of Materials and Methods are:

The irradiation as the degradation procedure is preferred because the accelerated ageing provides information on the contribution of filler (stabilizing component) on the improvement of thermal sterngth. A comparison of result is possible due to the similarity in the irradiation and measurement conditions.

The investigation procedure of chemiluminescence provides kinetic detailed information on the progress of degradation by the photon emission of oxidating free radicals through carbonyl configuration :

Accordingly, the modification in the studied material that is subjected to oxidation is followed because the concentration of carbonyl-containing degradation products is proportional with the number of recorded photons.

3. Needs to add some references in the discussion of Fig. 10.

Yes, we shall insert some comments related to the products appeared in degraded polypropylene.

The oxidation of polypropylene occurs by the reactions of free radicals with diffused oxygen. According with the background study on the radiation oxidation of polypropylene [42] each type of scission generates a certain fragmentation product that is further converted into oxygenated compound. During the propagation stage of oxidation, the accumulation of degradation products leads to the increase of the main structures that contain ketonic and hydroxyl moieties [43].

[42] Mowery, D.M., Assink, R.A., Derzon, D.K., Klamo, S.B., Bernstein, R, Clough, R.L.A solid state ¹³C NMR study using selective isotopic labelling. Radiat. Phys. Chem. 2007, 76, 846-878

[43] Bernstein, R., Thornberg, S.M., Assink, R.A., Mowery, D.M., Alam, M.K., Irwin, A.N., Hochrein, J.M., Derzon, D.K., Klamo, S.B., Clough, R.L. Insights into oxidation mechanisms in gamma-irradiated polypropylene, using selective isotopic labeling with analysis by GC/M S, NMR and FTIR. Nucl. Instrum. Meth. 2007, B 256, 8-17.)

4. The author should explain with relevant references (i) why 100 kGy irradiation is effective to compare to other irradiation and (ii) why sample P3 is most effective compare to other samples in Fig.11.

If the authors understood well, the comments on the behaviour of g-irradiated polypropylene must start from the basic consideration that PP is less stable due to the high concentration of tertiary carbon atoms [43]. On these spots the fragmentation is the most probable process. Consequently, the ratio between the scission and crosslinking radiochemical yields is higher than unity. The addition of stabilizers, even antioxidants or fillers like the present POSS structures, extends the resistance against oxidation during the radiolysis od PP. As it can be noticed from Figure 11, pristine PP is largely oxidized. Unfortunately, the structure P3 accelerates the degradation of PP, as it is also shown in Figure 3. It may be considered that P3, the structure containing methoxy substituent has a contrary effect on the restriction of oxidation propagation. It would be assumed that P3 configuration does not promote any cage effect that characterizes the contribution of POSS materials on the polymer protection against their oxidation.

Author Response File: Author Response.docx

Reviewer 2 Report

This manuscript presented some interesting results describing the degradation (oxidation) of polypropylene composite films. Indeed, authors analyzed significant amount of data bur some of this is not convincing and certain improvements must be taken before acceptance of the manuscript.

1) FTIR. The treatment of FTIR data must be clarified, because:

a) 50 scans can be too small number, as can be seen from low quality of your spectra

b) The changes in the COOH and OH peaks are not obvious, you have to take into consideration the integrates surface under curve

c) Most important! Altough you believe that the thickness of all you films were the same, it might not be so true. Better to check the intensity of CH2 and CH peaks.

d) Always operate the surface under the curve and your OH and COOH indices what is that? Please clarify

2) Complimentary study. Please check oxygen content using XPS or other methods

3) Typos. Too many mistakes, please check. E.g. line 311 evoluRion *=( I assume evoluTion).

Author Response

1. FTIR. The treatment of FTIR data must be clarified, because:  

a) 50 scans can be too small number, as can be seen from low quality of your spectra

Usually, the present authors recorded their FTIR spectra at this scan number:

Zaharescu, C. Mateescu, A. Dima, G. H. Varca. Insights into the antioxidant activities of Chlorella vulgaris and Spirulina platensis for innovative food packaging. J. Therm. Anal. Calorim., Doi: 10.1007/s10973-020-10319-4.

Zaharescu, M. Râpă, I. Blanco, T. Borbath, I. Borbath. Durability of UHMWPE/HDPE composites under accelerated degradation. Polymers, 12, 1241, 2020. DOI: 10.3390/polym12061241.

A.M. Lupu, T. Zaharescu, E.M. Lungulescu, M. Râpă, H. Iovu. Availability of PLA/SIS blends for packaging and medical applications. Radiat. Phys. Chem., 172, 108696 (2020). DOI: 10.1016/j.radphyschem.2020.108696

This choice is reliable, because the used spectrometer has enough sensitive detector for the accurate records at this condition.

b) The changes in the COOH and OH peaks are not obvious, you have to take into consideration the integrates surface under curve

You are right when you propose this method, but our evaluation approach is preferred by numerous published authors based on the close dependence between the concentration of investigated line and its hight at maximum transmission. This method was applied in all of our published papers, when the major spectral modifications are reported and where the transmission values are calculated in respect with base line.

Zaharescu, S. Scagliusi, A. M. Luchian, A. B. Lugaõ. Degradability characterization of EPDM/IIR blends by g-irradiation. J. Polym. Environ., 26, 616-625 (2018). Doi: 10.1007/s10924-017-0966-9.

Zaharescu. Stabilization effects of EPDM by doped inorganic filler for space and terrestrial applications. Mater Chem Phys., 234, 102-109 (2019). DOI: 10.1016/j.matchemphys.2019.05.068.

Zaharescu, I. Blanco, F. A. Bottino. Surface antioxidant activity of modified particles in POSS/EPDM Hybrids. Appl. Surf. Sci., 509, 144702 (2020). Doi:10.1016/j. apsusc.2019.144702.

c) Most important! Although you believe that the thickness of all your films were the same, it might not be so true. Better to check the intensity of CH2 and CH peaks.

The oxidation indices were calculated as the ratios between the maximum hight corresponding to the investigated function and the hight of reference, in our case 1475 cm^-1. Consequently, these ratios avoid the values of thickness existing in the Lambert-Beer law.

d) Always operate the surface under the curve and your OH and COOH indices what is that? Please clarify

Bagging your pardon, the authors would believe that this point was analysed at previous point 1b.

2. Complimentary study. Please check oxygen content using XPS or other methods

The accomplished XRD investigations (X-ray diffractometer – BRUKER AXS D8 Advance type, USA) did not show the involvement of oxygen on various stages of degradation or in the consistency of pristine POSS powders.

3. Typos. Too many mistakes, please check. E.g. line 311 evoluRion *=( I assume evoluTion).

The authors scanned carefully the text for the elimination of the possible editing mistakes.

The authors of this manuscript thank again for the useful comments and suggestions that sprung from the prodigious professional availability of reviewers.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

can be accepted.

Reviewer 2 Report

Authors skipped all recommendations instead changing their manuscript. The proposed arguments in the rebuttal are not convincing:

1) Using 50 scans because they always use 50 scans in spite of bad signal/noise ratio - I think this is quite weak explanation

2) Usage of height instead of integrating - again becuase it is easier and they did that way before. This is not good approach, especially when you compare spectra with badly setted baseline (that is obvious when you see the vertical shift)

3) Authors did want even to report CH and CH2 stretching height or area (2800-300 cm-1)!!! Why 1475 cm-1??? 

4) Avoiding XPS because you have not seen oxygen in XRD - this again not strong argument. XPS is more sensitive analysis!!!

The quality of the manuscript is not sufficient for renowned "Polymers" journal. Answers from authors clearly highlighted that they prefer to skip the revision and thus its quality was not improved by revision.