Fire Properties of Acrylonitrile Butadiene Styrene Enhanced with Organic Montmorillonite and Exolit Fire Retardant

Round 1

Reviewer 1 Report

The present study look into the fire properties of ABS co-polymer incorporating a nano-clay (organic montmorillonite) and a couple of different fire retardant. Some tests were conducted to investigate the improvement of using the above-mentioned additives compared with original ABS polymers. The paper is clearly-structured and the results are well-presented.

However, it seems to me that the addition of OMT does not give a significant improvement on the fire properties of ABS, although some minor improvement is made. It appears to be the fire retardant that plays a much more important role in enhancing the fire performance of the ABS. Thus, the authors may need to address the key advantage of adding OMT and the synergistic interaction between ABS, OMT, and fire retardant that may be beneficial for the fire properties of ABS. 

Also, as shown in Table 5, the results for reABS 1% OMT 20% FR looks very different from reABS 1% OMT 15% FR and reABS 1% OMT 18% FR. Likelywise for reABS 2% OMT 20% FR. 

If the authors can address the above issues, the work is considered to be publishable for Applied Science. 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript entitled “Fire properties of acrylonitrile butadiene styrene enhanced with organic montmorillonite and exolit fire retardant”, reference applsci-662395. It is a well written manuscript, easy to ready, and the use of recycled ABS is in my opinion commendable.

Nevertheless, I have identified some issues that the authors should address.

 

General comments:

The obtained results are interesting, and the experimental setup is logical and coherent. The discussion is solid. However, and I had the feeling that the authors do not obviously share their final objective. Meaning, I understand that the authors preformed their analysis, but for wat end? What is the application for the reABS with enhanced retardant capabilities? If this is clearly explained and highlighted, the impact of this manuscript would considerably be enhanced.

How important are the physical and mechanical properties of the obtained materials for the final application? How were these properties hindered by the addition of different concentrations of OMT and FR. In my opinion these are key parameters that were not considered in the described manuscript. Please comment.

In my understanding, the Introduction section should include additional information regarding de fire retardants used, to improve the contextualization of their use and to highlight their importance.

Point by point comments:

There is a complete lack of consistency in the acronyms definition, which hinders the reading. All the acronyms (including ABS which is only defined in line 78) should be define (once) when first mentioned, and must be consistently used throughout the manuscript.

Table 1 presents solely the properties of FR, unlike the described in the table caption correct? Please display the OMT properties.

Line 101, “120 mm x 10 mm x 4 102 mm3” is this correct?

Line 127, “affected the flame behavior of the nanocomposites significantly” were statistical analysis preformed, if so please adequately describe them in the Materials and Methods section.

Line 161, “average standard deviation of all measured mass loss calorimeter” in my opinion, it would be more accurate and appropriate to depict the standard deviation for each displayed value in table 4. Do the authors do not agree? Please comment.

Percentage is a unit, thus it must be separated from its numerical value. Please revise throughout the manuscript.

Line 204, “butadiene an styrene” there is a typo here correct?

Line 218, “reABS goes to an increase in residue by” colloquial language please revise.

Line 216, I beg your pardon, but I am not understanding the discussed values or residue ranging until 1060 %. I am simply unable to observe this values in table 4. Can you please clarify?

In my opinion, considering that reABS is a paramount standard for this manuscript, figure 2 and 3 should have reABS profile. I understand the simplification intended by the authors, nevertheless, in my opinion, the authors are wasting valuable visual information. The same goes for figure 5 and 6. In addition, in my opinion, figure 1, 2 and 3 should possess the same Y scale.

How many replicas and independent experiments did the authors performed to develop the model described in equation 1? Please describe this information in the Materials and Methods section.

In my understanding the Conclusion section should include further information of the potential of the developed material and a correlation to their end product or intended function/application.

Author Response

Answer to new Reviewer no. 2

 

We thank to the reviewer for its comments and observation, even if this report came after a decision was already taken by the Editor. In this case, we are doing our best to incorporate these additional comments in time. Plus, the reviewer can see in the revised paper also the changes in blue, changes that were suggested by the other reviewers.

Furthermore, it is inserted the answer to every comment, incorporated also with our response, new text/references added and comments.

 

The manuscript entitled “Fire properties of acrylonitrile butadiene styrene enhanced with organic montmorillonite and exolit fire retardant”, reference applsci-662395. It is a well written manuscript, easy to ready, and the use of recycled ABS is in my opinion commendable.

Nevertheless, I have identified some issues that the authors should address.

Response: Thank you for reviewing our article. We will do our best to respond to each comments and we hope that we will manage to address correctly all queries. All the modifications are highlighted in yellow in the revised manuscript and we hope that the reviewer will find the revised version acceptable.

 

General comments:

The obtained results are interesting, and the experimental setup is logical and coherent. The discussion is solid. However, and I had the feeling that the authors do not obviously share their final objective. Meaning, I understand that the authors preformed their analysis, but for wat end? What is the application for the reABS with enhanced retardant capabilities? If this is clearly explained and highlighted, the impact of this manuscript would considerably be enhanced.

Response: The aim of this study was to propose an improved material to replace the standard ABS for a number of applications, including fire resistant and low cost ones. This material can be used in the fabrication of parts for automobile industry, electronic components, construction materials and display screens, as well. Al these materials may take part in a fire scenario and their respective behaviour is of tremendous relevance. Also conclusion was enlarged, explaining the end uses of these materials (as is also the response to a further comment).

In this idea, new text was introduced in the introduction as:

The overall aim is to improve the global properties of ABS by taking into account two directions: costs (by replacing ABS with the recycled one: reABS) and fire behavior (by adding both OMT and FR to get better fire resistant properties). This study is of relevance for many areas like: automotive industry, electronics, civil engineering etc due to the large usage of ABS for components manufacturing and due to this material exposure in a possible fire scenario.

 

and in conclusion:

 

To conclude, it may affirm that the developed and tested materials may constitute a viable alternative to common ABS (i.e. an opaque thermoplastic and amorphous polymer with many real life applications) for the manufacturing of components for the automobile industry, as well as construction materials or other parts from domestic equipment (i.e. electronics, cases, toys etc). The use of improved fire resistant materials is very important, especially when a fire scenario may be involved. Nevertheless, more research is needed to establish the best and cheapest FR – OMT – ABS ratio to attain both economic advantages and an increased security in a fire incident.

 

How important are the physical and mechanical properties of the obtained materials for the final application? How were these properties hindered by the addition of different concentrations of OMT and FR. In my opinion these are key parameters that were not considered in the described manuscript. Please comment.

Response: Several comments about this were added in the article in regard to fire key parameters. We studied also the mechanical behaviour as well as few other properties, however it is the subject of another paper that is under review to another journal and we cannot introduce comments about it in this paper. The overall idea is that the experimental results of the mechanical tests revealed that the addition of organic montmorillonite increased the Young modulus, while the tensile strength is decreasing. As a conclusion of mechanical tests it can affirm that the best overall mechanical results were obtained for reABS 1% OMT 18% FR.

More details we can offer to the reviewer, but we cannot insert further insights in this paper. Thank you for your understanding.

 

In my understanding, the Introduction section should include additional information regarding de fire retardants used, to improve the contextualization of their use and to highlight their importance.

Response: We are not sure how much information is considered appropriate. We discussed already the research performed by Xia et al.[26], Lu et al. [27] and Despinasse and Schartel [28]. We also added some further insights. See the new text in introduction:

Multicomponent flame retardant systems containing aluminum diethylphosphinate in thermoplastic styrene–ethylene–butylene–styrene elastomers are investigated in terms of oxygen index, UL 94, cone calorimeter, and mechanical testing by Langfeld et al. [29]. Authors found that, by adding the fire retardant, an oxygen index of up to 27 vol% was obtained together with a horizontal burn rating in UL 94 with immediate self-extinction and the peak heat release rate decreased by up to 85%.

Concluding, such AlPi based multicomponent systems become a good alternative for fire retardant materials.

Ramani and Dahoe [30] studied the effect on flame retardancy in polycaprolactam composites with the combination of aluminium diethylphosphinate and organically modified montmorillonite nanoclay. The outcome of their study was that by joining both flame retardants, the result was an enhanced effect when compared with their application on a separate basis.

Guo et al. [31] studied the influence of modified ammonium polyphosphate (APP) on the flame retardancy of wood floor composite by cone calorimetry and noticed a synergetic effect between APP and the composite followed by a good improvement on the overall flame retardancy of the multicomponent material.

Similar results were outlined also by other research groups (please see for example Realinho et al [1], Xia et al.[26], Lu et al. [27], Despinasse and Schartel [28], Ma et al. [33]).

 

and new references:

Langfeld, K.; Wilke, A.; Sut, A.; Greiser, S.; Ulmer, B.; Andrievici, V.; Limbach, P.; Bastian, M.; Schartel, B. Halogen-free fire retardant styrene–ethylene–butylene– styrene-based thermoplastic elastomers using synergistic aluminum diethylphosphinate– based combinations, Fire Sci. 2015, 33, 157–177 Ramani; A.; Dahoe, A. E. On flame retardancy in polycaprolactam composites by aluminium diethylphosphinate and melamine polyphosphate in conjunction with organically modified montmorillonite nanoclay, Degrad. Stabil. 2014, 105, 1-11 Guo, C.; Zhou, L.; Lv, J. Effects of expandable graphite and modified ammonium polyphosphate on the flame-retardant and mechanical properties of wood flour-polypropylene composites, Polymers & Polymer Composites, 2013, 21, 449-456. Ma, H.; Tong, L.; Xu Z.; Fang, Z. Intumescent flame retardant-montmorillonite synergism in ABS nanocomposites. Appl Clay Sc. 2008, 42, 238-245. Mattausch, H. Properties and applications of nanoclay composites, in Polymer Nanoclay Composites, 2015, 127-155 Simionescu, T. M.; Minea, A.A. The effect of montmorillonite clay and fire retardants on the heat of combustion of recycled acrylonitrile-butadiene styrene, Environ Eng Manag J, 2019, 18, 317-326 Singh, P.; Ghosh, A.K. Torsional, tensile and structural properties of acrylonitrile–butadiene–styrene clay nanocomposites, Design, 2014, 55, 137-145. Wu, N.; Lang, S. Flame retardancy and toughness modification of flame retardant polycarbonate/acrylonitrile-butadiene-styrene/AHP composites, Degrad. Stabil. 2016, 123, 26-35. Zhuge, J.; Tang, Y.; Chen, R-H; Ibeh, C.; Hu Y. Flammability of carbon nanofiber-clay nano paper based polymer composites, Polym Advanc Technol, 2011, 22, 1403-1413. Ahmed, L.; Zhang, B.; Hawkins, S.; Mannan, M.S.; Cheng, Z. Study of thermal and mechanical behaviors of flame retardant polystyrene-based nanocomposites prepared via in-situ polymerization method, J Loss Prevent Proc, 2017, 49, 228-239. Wang, L.; He, X.; Wilkie, C.A. The utility of Nanocomposites in fire retardancy. Materials. 2010; 3, 4580–4606.

 

Point by point comments:

There is a complete lack of consistency in the acronyms definition, which hinders the reading. All the acronyms (including ABS which is only defined in line 78) should be define (once) when first mentioned, and must be consistently used throughout the manuscript.

Response: We checked and few modifications were performed.

 

Table 1 presents solely the properties of FR, unlike the described in the table caption correct? Please display the OMT properties.

Response: The table 1 caption was modified, while the OMT properties are already depicted in the text.

 

Line 101, “120 mm x 10 mm x 4 102 mm3” is this correct?

Response: Sorry for the typo. Now it is correct.

 

Line 127, “affected the flame behavior of the nanocomposites significantly” were statistical analysis preformed, if so please adequately describe them in the Materials and Methods section.

Response: We are not sure if we understood right the reviewer comment. There is no statistical analysis incorporated into this manuscript, except if we consider the regression analysis. The phrase was changed for clarity, see text in yellow, in:

The LOI and UL 94 tests results are summarized in Table 3 where it can notice that adding solely 15 % FR to the reABS affected the nanocomposites LOI, by increasing it with 7 %.

 

Line 161, “average standard deviation of all measured mass loss calorimeter” in my opinion, it would be more accurate and appropriate to depict the standard deviation for each displayed value in table 4. Do the authors do not agree? Please comment.

Response: We did not consider it as an essential point to be put into the tables, even if it is of major relevance for an experimental study and we tried to perform it and discuss it rigorously (that is why we calculated AAD for data). Also, the average standard deviation was simply calculated based on excell file. As an explanation, 2-3 tests were performed for each sample type and the average value was inserted in Table 3, for example. We added this explanation in Materials and methods. Please see:

For a better results accuracy 2-3 specimens were manufactures for each composition and tests were performed on 2-3 samples, while the average values were used for results discussion.

 

Percentage is a unit, thus it must be separated from its numerical value. Please revise throughout the manuscript.

Response: We checked and corrected this typo. Also, we double checked and separated all measure units from their numerical values throughout the entire manuscript.

 

Line 204, “butadiene an styrene” there is a typo here correct?

Response: yes, we corrected it

 

Line 218, “reABS goes to an increase in residue by” colloquial language please revise.

Response: We changed the phrase to:

Nevertheless, the addition of clay to the reABS determine a 155 - 296 % increase in the residue while adding the Exolit mixture to the base composite, the residue enhances to 560 %.

 

Line 216, I beg your pardon, but I am not understanding the discussed values or residue ranging until 1060 %. I am simply unable to observe this values in table 4. Can you please clarify?

Response: It is a misunderstanding and we re-wrote the sentence to make it clearer. Actually, in the first interpretation it was considered a three simple rule to determine the percentage increase if compared to the base value (1.6 %). Maybe it was unclear our explanation and we decided to keep it straight and clear.

 

In my opinion, considering that reABS is a paramount standard for this manuscript, figure 2 and 3 should have reABS profile. I understand the simplification intended by the authors, nevertheless, in my opinion, the authors are wasting valuable visual information. The same goes for figure 5 and 6. In addition, in my opinion, figure 1, 2 and 3 should possess the same Y scale.

Response: We modified the figures as reviewer suggested. Please see modified Fig 2 and 3 (same y scale and the reABS inserted), and also Fig. 5 and 6 (where reABS series is inserted).

 

How many replicas and independent experiments did the authors performed to develop the model described in equation 1? Please describe this information in the Materials and Methods section.

Response: We responded at this comment also before and information was added into the relevant section. The regression was performed based on experimental results and the technique is to use average data, at least from our experience. If data are affected by errors, it is not possible to obtain a good fit for the experimental data. We have some experience on this, in fitting manually the data and also by the help of computer. Also, we did not consider essential to add this kind of details here, as in any other similar paper or analysis.

 

In my understanding the Conclusion section should include further information of the potential of the developed material and a correlation to their end product or intended function/application.

Response: The conclusion was extended to cover all suggested information.

See the added text:

To conclude, it may affirm that the developed and tested materials may constitute a viable alternative to common ABS (i.e. an opaque thermoplastic and amorphous polymer with many real life applications) for the manufacturing of components for the automobile industry, as well as construction materials or other parts from domestic equipment (i.e. electronics, cases, toys etc). The use of improved fire resistant materials is very important, especially when a fire scenario may be involved. Nevertheless, more research is needed to establish the best and cheapest FR – OMT – ABS ratio to attain both economic advantages and an increased security in a fire incident.

 

Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript reported the fire properties of ABS polymers with the modification of organic montmorillonite and exolit fire retardant. The results the authors presented are interesting and useful. Therefore, this work could be worth publishing after addressing the following comments:

1 In the introduction section line 59, the authors first mention compound APP in the manuscript which I believe stands for ammonium polyphosphate. Although the authors gave us the full name in the Materials and Methods, it is better to use the full name when you first mention it in the article.

2 What is the difference in the polymers before and after burning in terms of the mechanical strength?  

3 According to the authors’ discussion, they highlighted the importance of the synergy from OMT and fire retardant. Is it OK for the authors to explain more about this synergy and how this combination improve the properties of the ABS polymers?

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Manuscirpt entitled: “Fire properties of acrylonitrile butadiene styrene 2 enhanced with organic montmorillonite and exolit fire 3 retardant”, reference: applsci-662395-peer-review-v3

 

The authors efforts to improve the manuscript quality are clear, and I am satisfied with the authors responses.

I just have a two suggestions of minor amendments:

Line 123: “120×10×4 mm3” should it not be 120×10×4 mm?

Line 313, “The analysis was performed by fitting the experimental data in Table Curve 3D software [47]” in my understanding, this information should be depicted in the Materials and Methods section.

Author Response

Please see the attachment.

Author Response File: Author Response.docx