Effects of Pulp Fiber and Epoxidized Tung Oil Content on the Properties of Biocomposites Based on Polylactic Acid
Round 1
Reviewer 1 Report
This is a very nice contribution to the field of sustainable composite materials. While this reviewer assumes that there is no significant fiber orientation because the samples were compression molded, this is not discussed explicitly in the paper. So the question remains: is there a preferential orientation? Just a short discussion about this would make this a more complete paper.
Author Response
The authors submitted the revised paper. The authors are looking forward to the next review of the reviewers.
Reviewer 2 Report
Major Revision
This manuscript is not proofread adequately and contains many errors. Please proofread adequately before submission.
Examples
-The abbreviation used is not defining appropriately. All short term of PF, NPF, SPF, ETO should be defined when first use.
-Please replace all … with etc. throughout the entire manuscript
-English should be improved for the entire manuscript
E.g. line 73, ….acetic acid is was gradually dripped…
E.g. line 68-69, Bad English
-Author need to check the typos in the manuscript like oC
-What is BCF fiber stand for (line 238)?
-Section 3.1.5. should be 3.1.4., please proofread adequately entire manuscript to avoid this kind of mistakes.
-Authors used Fig. x in text, but used Figure x in Caption. Please revised all the formats for consistency.
Technical section
-Line 56, Tung oil is one of the highest in iodine index thus promising good results when used as a plasticizer for PLA/pulp fiber composites (reference needed for this statement).
-A number of works related to the finding/results of modified pulp fiber reinforced PLA composite should be review in the Introduction section. Please mention the research gap why this research is carried out.
-Table 1 – What are the meaning of 3 ÷ 4 Fiber length and 30 ÷ 40 Fiber diameter?
-Line 78, Epoxy value of epoxidized Tung oil is 6.8%. How authors obtained this value?
-How authors confirm the epoxidation and grafting process of Tung oil with PLA or PF as proposed in Figure 1 and Figure 2?
Please provide evidence of oil epoxidization and grafting, for example – FTIR, NMR, ICP or GC-MS and etc.
Refer to this paper for oil grafting characterization - Chang, B. P., Thakur, S., Mohanty, A. K., & Misra, M. (2019). Novel sustainable biobased flame retardant from functionalized vegetable oil for enhanced flame retardancy of engineering plastic. Scientific reports, 9(1), 1-14.
-Authors mentioned an average value of five tests was reported in the mechanical testing method, but all the mechanical data presented are one value without standard deviation.
-Figure 5 TGA curves, how the x-axes can start from 20, 120, 220, 320…, Please check. The Figure title of x-axes and y-axes are bad i.e. overlap and degree C unit. Please revise
-What is the difference in processing between method 2 and the sample produce in section 3.2.1. It is very confusing. Please draw a schematic diagram to represent how each sample is produced.
-In mechanical properties presented in Figure 6, why only tensile strength and flexural strength are presented? Where are the data for tensile modulus, elongation at break and flexural modulus?
-Authors claimed that ETO act as a plasticizer in the composites to increase the flexibility, please provide elongation at break and modulus data. Plasticizer usually reduces the modulus and increase the elongation.
-The conclusion needs to be revised.
Author Response
The authors submitted the revised paper. The authors are looking forward to the next review of the reviewers.
- English errors, abbreviations, etc the authors have edited according to the comments of the reviewer (using "Track changes")
- The authors have added references to the sentence " as one of oil with the highest iodine index ..." (line 67), supplemented recent studies on PLA/pulp fiber composites (line 52 - 61)
- Because the length and diameter of pulp fiber affect on renforcement of fiber, the authors gived two parameters of pulp fiber
- The author has added the method of determining the epoxy value of tung oil (line 91 - 92)
- The authors think that the interaction between epoxidized Tung oil and PLA and pulp fiber is due to the interaction of epoxy group. So epoxidized Tung oil will also interacts as epoxyized vegetable oils.
- The authors added FTIR of ETO and PLA/pulp composites (section 3.1.3, line 203 – 216)
- The author has supplemented the mechanical properties with standard deviation (Table 3 and 6)
Author Response File: 
Author Response.docx
Round 2
Reviewer 2 Report
This revised manuscript is not proofread adequately and still contains many mistakes.
The authors even uploaded the wrong file in response to reviewer comments.
The English of the manuscript is still poor. Please provide a certificate of service of a professional English proofreading service if the authors have gone through that.
Please refer to my comments as below:
-line 69 contains a mistake
-Table 1 – What is the meaning of 3 ÷ 4 Fiber length and 30 ÷ 40 Fiber diameter?
-line 102: “Two”, avoid 2
-line 161, Ref 22 and 23 are more than one author, please use et al.
-line 192 used Fig. , line 199 used Figure, please check the consistency of throughout the manuscript.
-Figure 5 overlap with the Figure caption
-line 203, 204, typo, assigned
-line 212, typo, werw
-line 211, “Differential scanning calorimetry” not “Differential scanning chromatography”
-line 240 “The results showed that TGA curves of neat PLA and PLA/SPF composites exhibited one decomposition stage” this statement is not true, the PLA and PLA/SPF composites exhibited several decomposition stages after 350 °C. Please refer to your TGA curves.
-line 256, should be “flexural modulus” not “flexural strength”
-line 284, typo increase
-line 288, (15% of fiber), why the oil contain fiber?
-line 350, Ref. 25, typo, “flame” not “fame”
-The mechanical data presented in Table 6 are questionable. How can oil or plasticizer increase the toughness and stiffness simultaneously? When 5% ETO (Oil) added to the composites, the tensile modulus of PLA increased 800 MPa, The flexural modulus increases from 2.9 to 4.9 GPa with the addition of 10% oil (2 GPa stiffness enhancement with the addition of oil?). How is this possible? Did the authors purify the oil? Does the ETO contain a lot of impurities?
Author Response
Dear reviewer,
The authors submitted the revised paper and are looking forward to the next review of the reviewers.
- The authors have revised errors in lines 70, 103, 111, 131, 132, 162, 165, 168, 184 - 185, 193, 202 - 206, 208, 210, 212-214, 231, 260, 288, 293, 355.
- The authors have added a comment on TGA (lines 242-245).
- For the mechanical properties of Table 6, the authors think that when the ETO contents increases from 5 to 10%, the interactions between pulp fibers and PLA matrix gradually increase so that improved the mechanical properties. When content exceeds 10%, excess ETO made the material softer, the mechanical properties decrease (except for the elongation at break). Used epoxidized Tung oil is technical oil, not purifed.
Round 3
Reviewer 2 Report
I don't have any further comments
