Properties of Plywood Made of Thermally Treated Veneers Bonded with Castor Oil-Based Polyurethane Adhesive

Round 1

Reviewer 1 Report

The manuscript study the physical and mechanical properties of plywood manufactured with veneers treated at different temperatures by HT and TM treatment processes. This topic falls within the scope of the journal. However, the manuscript not only discussed the surface properties, but also included the mechanical properties. The title should be revised. The manuscript lacks the analysis of the impact of castor oil-based polyurethane adhesive on product performance. Publication is possible after major revisions, regarding methodology and interpratation of the results.

 Detailed findings:

Abstract

Line 26: The hydrophobicity of veneers is not related to the increase of lignin.

Line 28-32: The sentence is too long, please shorten to 2-3 sentences.

 

Material and methods

Line 143: What does “de” mean?

Line 151: one veneers side ? Delete s

 

Results

L195: Lignin is the most thermally stable chemical compound in the cell wall, why does it increase?

Table 1: The decrease in extractive content was observed for 180 and 200 °C in HM. Why?

L222: How to explain the increase in Ra for 180 in HT.

L224: The discussion on the influence of adhesive on wettability was missing.

L224: The discussion on the results and reasons under different processing methods was missing.

L246: The discussion on the influence of adhesive on EMC was missing.

L246: The discussion on WA and TS was missing.

L267: The discussion on the influence of adhesive on bond strength was missing.

L296-301: Discussion lacks literature support.

Discussion

L311: Delete “by”.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

I think that`s an interesting study, with an original starting idea and a very good research driving.

However, the bibliographic review must be actualizated and improve the citations in the text.

Author Response

We are grateful for your positive feedback on the original study idea and research approach. In response to your  suggestions, we have updated the bibliographic review and improved the in-text citations. Thank you.

Reviewer 3 Report

The work on "Surface alterations of heat-treated veneers and glue line shear of plywood bonded with castor oil-based adhesive" presented interesting results on investigation of thermal treatment of veneers on the properties of Plywood bonded with castor-oil-based-polyurethane adhesive.

However, the paper lacks of several scientific evidence, therefore it requires a major revisions.

Please see the comments below:

Title : The title is misleading. Please revise the title to “Properties of plywood Made of Thermally-Treated Veneers bonded with castor oil-based Polyurethane adhesive”.

 

Abstract:

·       Line 20-21. Please add the preparation castor oil-based Polyurethane adhesive briefly.

·       Please the glue spread used and the hot-pressing condition in the preparation of plywood.

·       The comparison with Commercial Polyurethane-bonded Plywood is missing. Please add it.

 

Introduction:

·       Line 44. Thermal treatment is TT not HT. Heat treatment is HT. Please revise.

·       Line 66. The degree sign in “180 °C” is not written correctly. Revise it.

·       The research gap of using Castor Oil-based-Polyurethane resins a plywood adhesive is missing in the introduction. There is plenty of research have been done in that area, for example:

o   Sugahara, E., Casagrande, B., Arroyo, F., De Araujo, V., Santos, H., Faustino, E., ... & Campos, C. (2022). Comparative Study of Plywood Boards Produced with Castor Oil-Based Polyurethane and Phenol-Formaldehyde Using Pinus taeda L. Veneers Treated with Chromated Copper Arsenate. Forests, 13(7), 1144.

o   Dias, F. M., & Lahr, F. A. R. (2004). Alternative castor oil-based polyurethane adhesive used in the production of plywood. Materials Research, 7, 413-420.

o   Chen, Y. C., & Tai, W. (2018). Castor oil-based polyurethane resin for low-density composites with bamboo charcoal. Polymers, 10(10), 1100.

o   Chen, Y. H., Wu, C. H., & Chen, Y. C. (2021). Optimized condition for eco-friendly wood composites manufactured from castor oil-based polyurethane. Construction and Building Materials, 306, 124789.

·       The aim of the study is missing at the end of the introduction.

 

Materials and Methods:

·       Line 101. The materials for the preparation of castor oil-based polyurethane adhesive are missing. Please add it.

·       The detail method of Preparation of Castor Oil-based Polyurethane adhesive is missing. Please add it.

·       The Castor Oil-based Polyurethane adhesive properties measurements are missing in the methods. Authors should run a test of a basic adhesive properties such as solids content, viscosity, and gelation time. Please read these published works and checked the basic adhesive properties measurements:

o   Sari, R. A. L., Lubis, M. A. R., Sari, R. K., Kristak, L., Iswanto, A. H., Mardawati, E., ... & Maulana, S. (2023). Properties of Plywood Bonded with Formaldehyde-Free Adhesive Based on Poly (vinyl alcohol)–Tannin–Hexamine at Different Formulations and Cold-Pressing Times. Journal of Composites Science, 7(3), 113.

·       Figure 1. The resolution is poor and the figure is not explained. The degree sign has underline in the Figure 1. Revise it accordingly.

·       Line 152. The Glue spread (adhesive grammage) is too high for plywood. It could create over penetration into the veneers. Do you have a reason why selected 395 g/m²? Industrial plywood usually uses 160-200 g/m². Lowering the amount of glue spread could reduce the cost of production.

·       Line 153. You wrote that the adhesive grammage was 395 g/m². But the next sentence you wrote consequently, 390 g of adhesive per board produced. Which one is correct, 395 or 390?

·       Line 157. It is a good idea to lowering the hot-pressing temperature. But in here you increase the hot-pressing time. Industrial plywood usually uses 4 minutes of hot-pressing time. Do you have a reason why selected 90°C for 10 minutes?

·       Line 161-172. All the Brazilian standard used in the evaluation of plywood properties should be written in the References.

·       Line 161. Delamination test is missing in the Physical Properties of Plywood. Delamination is one of the important physical properties of plywood. This is not acceptable. The authors should add the data of delamination test. In fact, water absorption and thickness swelling are not important in plywood, but they are necessary for particleboard and fiberboard.

·       Line 174-177. Please write briefly the testing methods of bending strength and shear strength.

·       Plywood bonded with commercial Polyurethane adhesive is required as a comparison for castor-oil-based-polyurethane adhesive.

·       Line 179-184. Please write the detail information of statistical analysis used in this work (Type, Brand, Country).

 

 

 

Results and Discussion:

·       The Castor Oil-based Polyurethane adhesive properties are missing. Authors should add the data of a basic adhesive properties such as solids content, viscosity, and gelation time.

·       Delamination result is missing in the Physical Properties of Plywood. Delamination is one of the important physical properties of plywood. This is not acceptable. The authors should add the data of delamination test. In fact, water absorption and thickness swelling are not important in plywood, but they are necessary for particleboard and fiberboard.

·       Plywood bonded with commercial Polyurethane adhesive is required as a comparison for castor-oil-based-polyurethane adhesive. Please add it the revision.

 

Conclusions:

·       The conclusion is well written.

 

References:

·       The authors should add recent articles (last 5 years) as references.

·       All the Brazilian standard used in the evaluation of plywood properties should be written in the References.

 

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Accept in present form

Author Response

We appreciate the reviewer for their support and attention to detail in the review process.

Reviewer 3 Report

The authors have revised the manuscript as the reviewer recommended. The manuscript can be accepted for publication after the following minor revisions:

> Line 98. Please write PU directly. The full name and abbreviation have been written at Line 88.

> Line 101. The details of castor oil-based PU resin is required in this section. Pleas write it.

> Line 117. Detail specification of pMDI, polyol, and castor oil are missing. Please check the following article:

Eco-Friendly Tannin-Based Non-Isocyanate Polyurethane Resins for the Modification of Ramie (Boehmeria nivea L.) Fibers. Polymers, 15(6), 1492.

> Revise "Bond Strength' of plywood to "Tensile Shear Strength".

> Line 432. Revise the degree sign. remove the underline.

> write "PU" instead of polyurethane. You already write "polyurethane (PU)" at Line 88.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf