Comparison of Mechanical and Electrical Characteristics of Various Polymers Blended with Ground Tire Rubber (GTR) and Applications

Round 1

Reviewer 1 Report

In my opinion, this paper is interesting for the readers because it evaluate the use of ground tire rubber (GTR) as a dispersed phase in a thermoplastic or thermosetting polymer by means of dilelectric and mechanical measures. The use of GTR is a solution for recovering and reusing the wasted tire which is a serious environmental problem due to the massive manufacture of tires and the difficulty of reducing the stocks of used tires.

I think that the objective is not very clear because the sentence is very long in the abstract. For my point of view, the introduction must describe the state of art of ground tire rubber deeper than it is described in the paper because it is too short. However, results and discussion of mechanical properties are too much based on the comparison of the values when the GTR is added to the different matrix that in the explanation of those results which I find much more interesting, especially in the mechanical properties. In addition, the most important results of mechanical properties are better described in the conclusions than in the corresponding section of results and discussion. By contrast, the electrical results are very good explained. 
With the aim to improve the paper, I suggest authors the following advices:-the double objective of the work must be clearer, because the sentence in the line 68 is too long. I understand that the double objective if this research is on one hand, the characterization and study of the physical properties of composite materials and on the other hand, the use of the compounds for the industry.-in the line 160, I believe that authors want to write that 20 per cent of GTR show the best behavior, however percentages of GTH greater than 20% show poor properties. In general, mechanical properties results are not clear. I think that authors must be revised the text, because some sentences are very confused as the 160 line are very confused, the next lines from 164 to 169, neither, I do not understand very well that authors want to say. For this reason, it is difficult to understand the conclusions of this section. In my opinion, it is clearer in the conclusion section.

Author Response

See the response in the attached file

Author Response File: Author Response.pdf

Reviewer 2 Report

The present research is about the mechanical and dielectrical properties of composite materials formed by ground tire rubber (GTR) and polymer matrix of verious chemical compositions. Several samples were prepared by using different concentration of GTR versus polymer matrix. The main experimental techniques used are mechanical stress-strain analysis (to evaluate the Young module, tensile strength, elongation at break and toughness) and the dynamic electric analysis (DEA). The results are presented but they are not discussed in detail. In particular, it is not clear if the measured properties at different percentages of GTR are related to eventual disomogeneity of the GTR particles and their dispersions. Any interpretation in terms of composite modelling is missing and the presence of general qualitative comments is not sufficient to justify a publication. This part should be improved.

Author Response

See the response in the attached File.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear authors,

In addition, authors explain the physical behavior of the polymeric compounds analyzed by means of electrical and mechanical models.

Now, Objectives of this work are clearer. Besides, arguments for comparing results and discussion are supported better with the incorporation of the new figure, equations and explanation added in this new version.

For the reasons showed above, I agree with the publication of this article as the present form.

Reviewer 2 Report

The paper has been improved in terms of quality of the presentation and discussion of the main results.

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

The authors examined the use of GTR as reinforcement and as conductive fillers for common thermoplastics. They measured the mechanical properties using stress-strain tests and the electrical properties using DEA.

A lot of data has been produced, but its significance is very unclear, as no comparisons to the alternatives are presented. Are GTR grains supposed to be reinforcing? What is the most common reinforcement and how are they compared to it? The authors claim the increase in conductivity is due to the carbon black inside the GTR - how is its performance compared to pure carbon black? Maybe something else is in action here, maybe the GTR presents a cheaper alternative with same qualities - or maybe it's not worth the effort - but the authors presented us with no context to evaluate their results. 

Thus, in its current form, I recommend the rejection of this paper, as I am far from convinced in its merits.

Reviewer 2 Report

This work deals with the evaluation of dielectric and mechanical properties of composites made of ground tire rubber (GTR) and polymers. This paper addresses the problem of reusing GTR and reduce several environmental problems.

Several material composites have been prepared with different concentrations of GTR. Basic experimental methods have been used and commented in order to understand the possible applications and recycling possibility taking into account legal regulations.

The paper is clear and the results are coherent and sound.

Several minor typos and gram errors should be corrected before publication.

Reviewer 3 Report

This paper reported that the mechanical properties of the thermoplastic polymers blending with ground tires rubber(GTR). The mechanical properties of blending polymers are highly dependent with the compatibility of the polymers with rubber. However, this paper did not add any coupling agent or modify GTR before mixing. I did not think it is not a fair comparison. The rubber/polymer blends are named “toughness”, not a “reinforcement”. The title of paper should be modified.  

1.Line 73, “polyetilene” should be modified to “polyethylene”.

2.Line 87, why the “(styrene-butadiene-styrene)” was presented in sentence? This polymer is not transparent.

3.Line 137,139 and 147, the name of Figure should be the identical presentation.

 …

I did not recommend to accept this paper at this stage. The author should be modified before it is resubmitted.