Characterization of Thermal Bio-Insulation Materials Based on Oil Palm Wood: The Effect of Hybridization and Particle Size

In the Abstract

Q1

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In my opinion, instead of "modulus bending", "Modulus of Elasticity in Bending" should be used, or just "Modulus of Elasticity". I recommend for this property also use the dimension MPa (as for the bending strength) and not GPa

R1

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I appreciate your advice. I have revised the sentence in the manuscript.

Q2

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Please add the main novelty in your research in this section

R2

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I appreciate your suggestion.  I have added the novelty of this paper in the abstract of the manuscript on lines 15-19.

In the Introduction:

Q3

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Please expand the review for bio-based binders, not only for starch but also for tannins, lignin, lignosulfonates and others. On this basis, increase the number of references

R3

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I appreciate your suggestion. I have added the related reference and include references in the manuscript in lines 106-114.

Q4

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Please specify the sentence “Bio-binders are used as resins to make completely natural insulating materials” (lines 88 ÷ 89). Bio-based binders are used not only for insulation materials but also for wood-based panels for furniture production, construction purposes and so on

R4

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I appreciate your suggestion. I have revised the statement in the manuscript in lines 104-106.

Q5

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Please justify the regime used for the pre-treatment of fibres (lines 136-140).

R5

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I appreciate your suggestion. I have justified the regime used for the pre-treatment of fibers in lines 165-171

Q6

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Why were particles boiled in water at 100^O C for 30 minutes and not for example for 40 minutes? Please provide references justifying the regimes you used

R6

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I have appreciated your question. I have explained the pretreatment of particles boiled in water at 100^OC for 30 minutes and added references justifying the regimes used in the manuscript (lines 165-171).

Q7

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The same applies to a much greater extent to the hot-pressing regime. The specified pressure of 9.8 MPa is very high. Usually, the first-stage pressure for panels with a density of 0.70 g/cm³ is in the range of 4 ÷ 5 MPa. You may have given the manometric pressure (the pressure in the hydraulic system). If this is the case, please give the specific pressure (pressure on the pressed material). Please provide in more detail the regime of hot-pressing - how many stages are used, pressure and time at each stage. How do you choose the press factor (time of hot-pressing)?

R7

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Thank you for your comment and suggestion. Your suggestion could be very relevant to improve our validation method in future work. In this study, the panels were manufactured based on oil palm wood (OPW), which the essential characteristics of OPW have low physical and mechanical properties. In previous work, we evaluated pressures below 9.8 MPa we did not achieve the target density of 0.7 g/cm³. Therefore, we increased the pressure to 9.8 MPa to get the density target.

The choose the hot-pressing factor, many stages are used, pressure and time at each stage after explaining in the manuscript (lines 182-185)

Q8

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Please explain how you set the target density of the panels. Typically, the density of insulation materials is in the order of less than 0.4 g / cm³.

R8

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Thank you for your comment, and we agree with your statement that the density of insulation materials is typically in the order of less than 0.4 g/cm3. However, in previous works, we found that the density of OPW panels in the range of 0.4-0.5 g/cm³ has low physical and mechanical properties. Therefore, we increased the target density to 0.7 g/cm3 because this work is also an effort to obtain panels with low thermal conductivity and good physical and mechanical properties.

In the Results and Discussion

Q9

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Please explain the variation in the density from 0.66 to 0.79 g / cm3. This variation is 20% and it will affect all the properties of the panels, even if they are of the same composition.

R9

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I appreciate your suggestion. I have explained these in the manuscript in lines 290-295.

Q1

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The manuscript is focused on investigation and evaluation of the physical, mechanical, and thermal properties of bio-based insulation materials, fabricated from oil palm wood and ramie, bonded with tapioca starch as a bio-adhesive

R1

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We would like to thank the reviewers for this statement

Q2

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The title of the manuscript (lines 2-4) is clear and informative.

R2

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We would like to thank the reviewers for this statement

Q3

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In general, the abstract (lines 15-32) and the keywords (lines 33-34) are specific and correspond to the title, aims and objectives of the manuscript.

R3

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We would like to thank the reviewers for this statement

Q4

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In lines 19-20, the sentence “A panel was prepared using hot-press at a temperature and pressure constant.” is not very clear, and should be revised, e.g. by providing specific information on the press regime. In addition, I believe the authors produced more than just one panel, please revise accordingly

R4

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I appreciate your reminding. I have revised the sentence in manuscript (lines 23-24)

Q5

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In line 30, please delete the unnecessary “was”.

R5

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I appreciate your reminding. I have deleted the character.

Q6

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In lines 33-34, I’d suggest to replace “natural binder” with “bio-based adhesive”, and “physical and bending properties” with “physical and mechanical properties”.

R6

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I appreciate your suggestion. I have replaced this word (lines 40-41).

Q7

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In line 38, please revise the first sentence, it’s not very clear, e.g. “Indonesia is the biggest producer of palm oil worldwide”.

R7

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I appreciate your suggestion. I have the replace the sentence in manuscript (lines 44-48)

Q8

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In line 71, I’d suggest the authors to add some information related to the valorisation of tree bark for thermal insulation panels. Please refer to the following recent references in the field:

https://doi.org/10.1007/s00107-019-01436-5  

https://doi.org/10.1016/j.conbuildmat.2017.04.204

https://doi.org/10.3390/polym13142287  

https://doi.org/10.3390/polym13111799   

https://doi.org/10.1016/j.conbuildmat.2020.121577

https://doi.org/10.3390/app10165594

R8

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I appreciate your suggestion. I have included the reference in to the manuscript (lines 87-91)

Q9

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In lines 79-80, there is no need to use capital letters for urea-formaldehyde and phenol-formaldehyde resins, please revise.

R9

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I have replaced the capital letters with a small case

Q10

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In line 83, apart from the poor biodegradability, the most important drawback of the commercial thermosetting resins such as UF and PF is the emission of VOCs, including free formaldehyde from the finished composites, which are linked with serious negative effects on human health, including cancer. Please add some information and references.

R10

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I appreciate your suggestion. I have the revised the sentence in manuscript (lines 96-99)

Q11

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In lines 86-88, I’d recommend to the authors to add some information on the other important types of bio-based adhesives for production of lignocellulosic composites, such as tannins, soy, and lignin. Please refer to the following interesting publications:

https://doi.org/10.7569/RAA.2021.097307

https://doi.org/10.3390/polym12051115

doi:10.32604/jrm.2021.012782

doi.org/10.37763/wr.1336-4561/65.1.051062    

https://doi.org/10.1007/s00226-020-01248-4

https://doi.org/10.3390/ma14174875

https://doi.org/10.3390/polym13162775

https://doi.org/10.1007/s00107-006-0130-z

https://doi.org/10.1016/j.jclepro.2021.127892

http://doi.org/10.1007/s00226-017-0957-y

http://doi.org/10.3390/molecules26154526

R11

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I appreciate your suggestion. I have added the related reference and include references in the manuscript (lines 106-114)

Q12

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In lines 107-109, the sentence “Different analysis equipment, such as universal bending testing machine, high insulation house, and TGA, are used.” does not belong to the Introduction, please remove it.

R12

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I appreciate your suggestion. I have deleted the sentence

Q13

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Overall, the Introduction part is well written and informative, but can be further elaborated based on the comments provided.

R13

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We would like to thank the reviewers for this statement

Q14

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In lines 112 and 114, I’d suggest to add the botanical names of the species used in the research, i.e. oil palm and ramie.

R14

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I have add the botanical names of oil palm (Elaeis guineensis) and ramie (Boehmeria nivea) in the manuscript.

Q15

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In lines 115-116, please add some information and characteristics of the bio-based binder (tapioca starch).

R15

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I appreciate your suggestion. I have the added some information and characteristics in manuscript (lines 138-142)

Q16

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In line 119, Table 1 is not the correct one. It is equal to Table 2 (line 150). Please add the correct table about the chemical composition and properties of the materials used in the research.

R16

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I appreciate your reminding. I have corrected the table with the real one

Q17

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In line 143, please add some information about the hot press used (company producer, city, country).

R17

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I appreciate your suggestion. I have the added some information about the hot press used in the manuscript (lines 174-175)

Q18

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In line 145, please add information about the mixer used.

R18

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I appreciate your suggestion. I have the added some information about the mixer in the manuscript (lines 177-178).

Q19

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In line 148, please explain the selected hot pressing parameters, e.g. based on preliminary trials, other references, etc.

R19

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I appreciate your reminder. I have explained some information to selected hot-pressing parameters in the manuscript (lines 180-188).

Q20

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In line 166, please add the respective standard (SNI 03-2105-2006) in the manuscript references. The same comment applies to line 171 (ASTM D70), and line 181 (ASTM C177-9). In addition, I believe the correct standard in line 181 should be “ASTM C177 – 19. Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus”, please revise.

R20

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I appreciate your reminding. I have revised the sentence in manuscript

Q21

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In general, the Results and Discussion section is well-structured, concise, informative and discussed with previously published research works

R21

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We would like to thank the reviewers for this statement

Q22

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The Conclusions (lines 353-373) are consistent with the results and reflect the main findings of the study.

R22

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We would like to thank the reviewers for this statement

Q23

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The references cited are appropriate and correspond to the topic of the manuscript. The inclusion of additional references in all sections of the manuscript is highly recommended. This will significantly increase the value of the presented work

R23

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We would like to thank the reviewers for this statement. We have added some relevant references according to the suggestions of reviewers.