Moisture in carbon plus vinyl ester

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#1

I infused a hand full of parts yesterday, (the first super humid day of the year in South Florida). The infusion was perfect. But a few moments later I saw tiny air bubbles start popping up in different spots of the mold. The same pattern over all of my parts in two infusion runs. Various size and shaped molds.

My only theory is moisture absorbed into the carbon fiber and fiberglass due to the super humid day. I also had a giant exhaust fan running in the shop all day and I’m assuming that vacuumed in lots of fresh moist air? What do you guys think?

I’ve been infusing with MVR infusion resin from inter plastics I believe the company name is.

The first batch of parts were done with MEKP-9 and the second was with MEKP-925.

I freaked out and decided to stop production to build a layup lab in the shop. A 20 x 15 ft white room sealed from the shop with AC and a dehumidifier. Is this 100% necessary? Are there ways to get around the moisture problem?

I also believe its worth noting that the first run was infused after the parts were under vacuum for an hour. I knew it was real humid so I let it run longer to see if the humidity can be vacuumed out. The second I waited 10 min out of frustration.

#2

I would leave the parts under vacuum for at least an hour to boil off any moisture. Also, this gives you time to perform a drop test to determine if you have any leaks.

#3

I’m sure you konw that VER does a nice bubbling as it cures. You might try to lengthen the pot life, and degas it. Else, yes, humidity will cause issues sometimes, but you said the first already was under vacuum for an hour. Obviously, try 2 hours, or heat the part if possible. Make sure th bag/bagging is perfect, along with and tube connections.

#4

Thanks guys :). Will post pigs of results.

#5

2 things: moisture can be a problem. Keeping the parts under vacuum helps boiling off the moisture. Rig a digital vacuum meter into your setup, and watch it as air gets evacuated. At some 20 mbar water starts boiling off, and the pressure drop stalls at that value. At a certain time (moisture gone) the pressure will drop further. Wait for this to happen.

Another factor indeed is the VE combined with MEKP. Especially the H2O2 containing MEKPs will generate some gas. Usually this stops after the H2O2 is gone, which can be 5 minutes or so. Degassing helps to get rid of the last amount of gas.

I believe both MEKP-9 and MEKP-925 are H2O2 free.