Testing MG Chemicals 8800

Owned by Micah Black
Last updated: Jan 10, 2021
3 min read

We purchased some MG Chemical 8800 Flexible Polyurethane Potting Compound from Newark to see how well it would hold up.

I used an old prototype of the battery busbars and cell holders, and pretty much just poured the 2-part mixture over the top.

It was a not a very viscous liquid, and spread out very easily - which is good, since we want a thin layer over a large area. I also placed a piece of acetal on top to see how well it would stick. I mixed about 16mL of part A and 8mL of part B in the mixing cup and stirred for a minute or so before pouring it over the parts.

It requires 24h at room temp to cure, so we’ll have some results tomorrow.

 

After letting it sit in my room for 24h, the resin had solidified to a little softer than those red, blue, and white bouncy balls. It stuck to the acetal piece that I put on top of it, the nickel clad busbar, and the PETG cell holder fairly well. I think it will stick much better to ABS since that tends to like glue better than PETG, at least from what I have seen. Overall, we will definitely move forward with it!

 

A note about the curing process:

  • Once the two parts are combined, the compounds start interacting and producing heat in an exothermic reaction. This heat increases the speed of the curing process. When all of the compound is in the mixing container, there is little surface area to the outside, so it heat up quickly. Once poured out of the container, onto an surface, there is much more stuff in contact with it to remove the heat and act as a heat sink, so it will cure more slowly.

 

A few things to note during our further testing with the module assembly:

  • The time between combining the two parts and the time when it should be poured should be about 2 minutes. This allows the compound to cure and harden a bit before being poured so that it will be more viscous. If this time is not given then the potting compound will leak down in the small gaps between the cells and the cell holder. If too much time is given, the potting compound will not be able to spread around as it will be too viscous.

  • We have found that mixing together 45mL total (30mL part A and 15mL part B) is a good amount to use for each side of the module.

  • The ratios between the 2 parts and being fully mixed are super important. We have had some pours not curing completely if not fully mixed - mix it for the full 2 minutes, ensuring to scrape the sides and everything.

  • When pouring the potting compound over the modules, only pour it up to edge of the cell holders - we do not want a surface tension bubble holding it in. When we clamp it together with the acetal cell cover we don’t want it to spill over the edge.