Marine Adhesives

Making an adhesive bond to a rock was the most difficult task. Shown above, cadets at the "Hard Rock Cafe."

Today at The Mass Martime Academy Professor Sichel broke us up into two different groups. I was in groupI. We had four cadets and three technicans, including me. We went to the floating dock to figure out a way of suspending the sample cage from the inside egde of the dock. We had to collect four five-gallon buckets of sea water to bring back to the lab. While we were outside, we were asked to measure the water temperature with the thermocouple thermometer. After we accomplished the first task we all filled the working trays with a inch or two of the sea water, making sure we kept at least two five-gallon buckets full of seawater for later. Then My cadet and I worked on preparing samples of rocks under the water. Our Group tested three new expoxies with the rocks that we had chosen (to work on). I helped cadet Holcroft label the plastics with the correct id number that looks something like this: 010925EPW and 010925PC-11. The (metal) tags were suppose to work with a stylus (instead of a pen). The chemicals that we used to do the second task were PC-11 All Purpose Expoxy white glue and Water-Proof Expoxy. (This is used for filling in gaps and repairing pipes underwater.) We mixed the epoxy according to the package (directions) and smoothed it on to the rocks to see if our (metal) labels would stick. I also used Expoxy 88, which was in the white and black tubes. I learned if an expoxy comes off (leaving the adherend) clean on both sides, it is considered a (failure of) adhesion. If an expoxy comes off clean only on one side, it would be a (failure of) cohesion. After we did the second task we went back to the floating docks and transferred the samples to the cage and left them outside for life testing. To summarize what I accomplished today: the "smart glue" marked and made a bond with the plastic (and the rock). Ace epoxy--also known as the store brand--stuck to the plastic under pressure, but the epoxy didn't wet the rock (surface). PC-11 epoxy failed (to bond to the rock). ------------------------------------------------------------------- On September 25th 2001 I helped cadets write on tabs with indelible ink. We wrote the codes of the adhesives and the metals we were using on our tabs (metal marking tags). Then we measured two inches from the bottom of the metals (for testing fixtures) and drew a line. On the wood (fixture) we measured one and a half inches and drew our line. These lines represent the sections that will have an epoxy on them. Then we carefully put epoxies on our samples and pressed another sample against it to form a bond. Example: aluminum to aluminum. After that, we cleaned up our lab bench and went back to the classroom to discuss last week's samples and results. ------------------------------------------------------------------- Smart Glue 1. My lab partner and I put on our gloves and safety glasses. 2. We chose a rock with a smooth surface to start our tests with, remembering that the volcanic rock was smooth. 3. The epoxy came in a tube, which was divided into many sections. We followed the instructions and broke open the bottom section, pushing its contents up through the package to mix with the substance in the other half. 4. Next we applied the glue to the rock under the water in the tray and then fastened the label on the rock by means of the glue, and a rubber band in the event the glue did not hold. 5. We repeated steps 3 and 4 on a second rock, this time choosing a rock with a relatively rough surface. We did not score either rock. When we returned to check whether or not the epoxy adhered to the rocks and held the label on, we found that it had. The problem I saw was with the label itself. It did not (conform to) the curvature of the rock so that when enough pressure was applied in the effort to pull it off, it was accomplished easily. A material that would conform to the rock while maintaining the strength might be effective. -------------------------------------------------------------------- This week my job was to go down to the docks by third company with two other cadets and three technicians. We had to select a place where we could later submerge our experiments in a metal cage while in an open environment. While we were down by the water other cadets and technicians were preparing the experiments in the lab room, by washing and degreasing the metals. We used aluminum tags that we scribed information onto in case the (ink) marker came off the tags while in the salt water. The information was epoxy codes, curing conditions, materials, and the date. I think that the epoxy will hold up`in the conditions off the dock. I don't think that there is too much current to disturb the samples. My only concern is any kid of chemicals that might flow by the samples. An idea that I came up with to label the sample under water was to use a paint pen also called a paint marker. I went to the ACE hardware in Borne on the Cranberry Highway in the Walmart and Super Stop and Shop complex (to obtain such a paint marker).

Report #4b: interview with MMA Professor Robideau on the topic of testing strength of materials

The following tests can be can be completed in the (MMA) strength of materials lab: compression, tension, peel, and shear. The equipment in the lab can produce forces upwards of 100,000 pounds. For accuracy under 100 pounds the lab is not well equipped, although there is one manual machine which is used for smaller tests. The data from the tests can be recorded from various gauges and a computer generated plot can be obtained. Any sample can be tested in the lab as long as it can be grabbed with a clamp, which can be easily made by a machinist. The best way to test the materials would be to grab the sample equally along the edge being pulled or compressed. Dr. Robideau mentioned that the surface area that the adhesive is applied to will effect the forces necessary to make the sample fail. Dr. Robideau also suggested that we conduct a double shear test which involves placing one sample in between an cutout from another and being able to equally pull the sample apart causing no additional forces applied to the sample, possibly skewing the results of the test. -------------------------------------------------------------------- Q. What equipment does this academy have, and where is it? A. We have the equipment to do tensile and compression tests, and it is in the Storer Building, on the eastern side. We have a lab every Monday, Wednesday, Thursday, and Friday from 12-1. Q. What can affect results? A. The only thing I can think of, is the amount of surface area applied with the adhesive, and the uniformity of the force. Q. Anyway we can submerge the specimens while testing? A. No, the closest you thing you can get to that, would be to submerge asample, then immediatly test it. Q. Anything else you can think of? A. Just to test how an adhesive reacts to shear.