Epoxy Impregnation Experiments
- Former user (Deleted)
Attempted on Exp 384, replicate procedure from Geosciences article Low Cost, Lightweight Gravity Coring and Improved Epoxy Impregnation Applied to Laminated Maar Sediment in Vietnam
Materials:
Nylon mesh from spares in paleo lab, cut into approx 6.5cm square pieces
Headspace sampling cylinder, approx 1.7cm diameter, must be slightly smaller to fit inside larger cylinder
Larger sampling cylinder with plunger approx 2cm diameter
Soldering iron tip or other small heat source to slightly melt nylon mesh
Peristaltic pump (spare from STMSL track) and tubing
Centrifuge tube with flat bottom
To make the nylon mesh sampling tube:
Use small squares of the mesh and wrap them around the smaller cylinder, melt the overlapping edge with the soldering iron tip (heat level used about 450, higher and it will melt too much, lower and it won't melt enough). You should be left with a mesh sleeve that fits inside the larger sampling cylinder with plunger. Put the mesh inside the cylinder and use that to take a sample of soft sediment. Pushing the plunger should push the entire mesh sleeve out with sample intact and hopefully undisturbed. Stuff small pieces of kim towels in the top and bottom of the mesh sleeve and sit inside the centrifuge tube.
To make circulating apparatus:
Use small drill bits to make a hole in the bottom of the centrifuge tube for the acetone and epoxy to be drained away. I used the smaller tubing that comes with the Petropoxy kits so that I could keep the hole small. The peristaltic pump needs to use the larger tubing that is kept in the phys props lab above the WRMSL track. I connected the two tube sized with a swagelock connection and teflon tape and zip ties (look at the WRMSL set up for inspiration). The small tubing siphoned the acetone or epoxy out of the sample, and the larger tubing dripped the liquid back on to the sample for full circulation. I filled the centrifuge tube with acetone and let it circulate for approximately 2 days while checking every couple of hours and topping off the acetone that evaporates, I kept glad wrap over the top to keep evaporation down. Do this in the fume hood.
Acetone and Epoxy exchange:
After 2 days of circulating acetone I began adding batches of epotek epoxy to the centrifuge tube. To make one "batch" I used 6ml of part A and 2ml of part B. I added more batches as the acetone evaporated and there was more room in the centrifuge tube to add more liquid. Over 3-4 hours I had added 4 batches of the epoxy. I added a small amount of blue epoxy dye to the mixture to be able to see the circulation better and in the hopes that if the epoxy cured you'd be able to see how far into the sample the epoxy penetrated. I let the epoxy/acetone mixture circulate for a few more hours to evaporate more of the acetone. Eventually I removed the nylon sleeve and sample and placed it in an impregnation mold (to catch all the drips) to cure at room temperature. I purged the rest of the epoxy/acetone from the tubing into paper cups to dispose of. I cleaned out the tubing reasonably well by circulating acetone through it a few times, the dye also helped with this to see when it had all been rinsed out. The tubing looks to be in good enough condition that it can be used again.
Results:
The sample soaking in the epotek epoxy never fully cured, it stiffened up but remained gooey and tacky (because it is not meant to be combined with so much acetone) and I did not attempt to cut into the sample because it was still too soft for that. However, creating the apparatus proved that this procedure could be accomplished in the future with using the proper epoxy. Hopefully when the Petropoxy arrives to the ship it will work better with this type of impregnation!