Measuring, Cutting, and Kitchen Chemistry

Nicholas A -

Hi everyone!

I finished cutting and adding grips to the first composite panel this week. To do this, I first measured and cut the panel to 10.5 in x 10.5 in. Then, from a large panel of phenolic linen, I cut four identical 10 in x 2 in grip tabs. With a belt sander, I tapered one of the long sides of each grip tab to about 45 degrees. This is important to do because it prevents stress concentrations at the edge of the grip, which could cause the test specimen to fail prematurely. Finally, I glued the grips onto each end of the panel. The next step is to cut 10 test ribbons, each one inch wide. 

I also did some more investigation into the graphene oxide that we already have. Originally, the GO was dispersed in water with a concentration of 5 mg/ml. Unfortunately, since the container is old, it seems like a lot of the water evaporated, and now we have a black paste. This also means that the GO has clumped up and needs to be exfoliated again to separate all the layers again. This can be done by sonication, but unfortunately we don’t have a sonicator, so I’ll have to find another way. I did take some pictures of the GO solution, and it’s clear that there are some large flakes. 


Transferring the graphene to the epoxy is also difficult. Water does not mix with epoxy, so I can’t simply pour the solution in. I could potentially gradually replace the water with isopropyl alcohol or something similar, which would mix with epoxy. Then I could just evaporate out the alcohol. Alternatively, I could try to find a way to dry out the solution and add the powder to the epoxy and mix it in. 

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    Dishita Kolla
    Hi! The composite panel sounds interesting! Have you considered using a different material for the grip tabs besides phenolic linen? I'm curious to know what other options might be out there.
    Nick, your work with different materials is impressive. I am interested in why the epoxy doesn't mix with water? Why would isopropyl alcohol be a better option?
    Hi Dishita, I'm using phenolic linen because it's what we have available. Usually, grips are fiber woven composites like phenolic linen or the ones I'm making. There are other options like emery cloth, which is usually just held in place by friction at the grips. Ultimately, making grip tabs to get reliable tensile test results is more of an art than a science.
    Thanks Ms. Bennett! Alcohols mix with epoxy but water doesn't because they are chemically more similar to epoxy than water. There is a saying: "like dissolves like," and, like epoxy, alcohols have carbon atoms in their structure, while water does not. I need the solvent to mix with the epoxy in order to transfer the graphene oxide, so I used isopropyl alcohol.

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