Mixed Carbon Nanomaterial/Epoxy Resin for Electrically Conductive Adhesives

Round 1

Reviewer 1 Report

The manuscript by Lopes et al. deals with the production and characterization of electrically conductive adhesives by incorporating carbon nanostructures as nanotubes and exfoliated graphite. At first sight, it seems to be a carefully conducted research work and prepared manuscript with many results and techniques. Nevertheless, I have quite a few (some of which fundamental) concerns.

Novelty of the work is low. You mention (lines 236-238) that according to SEM and Raman, the EG you use is very good and better than rGO in another study. Nevertheless, in Figure 4 we see that even at high content the resistivity of the ECA is high and significantly higher than that of ECAs with CNTs. Have you checked the quality of the EG used? Is it highly exfoliated? Have you checked it with AFM? If it does not add much to the quality of the final material, why adding it? Keep in mind the cost of HQ EG for answering that. I would expect to see vital enhancement of the ECA conductivity upon graphene-related material addition. In addition, there seems to be a randomness (and huge variation) of the conductivity upon EG addition, and I am far from convinced by how you try to explain it in page 8. Regarding pros and cons, there is certainly a big disadvantage compared to the silver ECA, i.e. the orders of magnitude lower conductivity, that is also the most significant feature of the paste. Hence, what is the advantage, this ECA has to offer? Is it really so much cheaper to use SWCNTs plus EG so that its use is reasonable, considering also the cons? Is it a typo the resistivity of the tenth sample in Table 1? You present SEM images of a sample 2% MWCNTs in Figure 5 but you don’t seem to have such a sample in Table 1. There are a few typos.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The authors prepared the electrically conductive adhesives (ECAs) based on epoxy/carbon nanoparticles (single and multi-walled carbon nanotubes and exfoliated graphite) within a range of concentrations. The composites were performed a series of characteristic tests and deposition on a test printed circuit boards (PCBs). In my opinion, the paper is suitable to be published in Journal of Composites Science after revised the manuscript. Some notable comments are as following.

1. In this manuscript, the carbon-based materials were incorporated on epoxy resin to obtain the composites. However, the carbon nanotubes are 1 dimensional materials, while exfoliated graphite is 2 dimensional materials. In my opinion, these carbon-based materials cannot be called nanoparticles. Please change the name of the carbon-based material.
2. Please provide TEM images of SWCNT, MWCNT and EG to observe the hollow of carbon nanotubes and layered graphite structure.
3. In Table 1, please evaluate the electrical volume resistivity of the composites in same concentration of carbon nanotubes. Additionally, please provide the electrical volume resistivity of composite in 1.2 wt% SWCNT + 0% EG of composition.
4. For Raman spectroscopy mapping test, please compare the G band intensity distribution of composites in the same of z-axis vertical positions.
5. In AFM analysis, please clearly explain the difference surface morphology of epoxy composites with 1.2 wt% SWCNT and 5 wt% EG.
6. Why is the thermal conductivity of a series composites of 0.2 wt% SWCNT with different EG contents of 2 and 5 wt% lower than epoxy with different EG contents of 2 and 5 wt%?
7. In Results and Discussion section, the authors need to compare the carbon-based electrically conductive adhesives with other conductive adhesives like metallic fillers and its various structures.

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Authors have replied to my comments and have made appropriate revision.

Reviewer 2 Report

The revised paper could be published in JCS.