2. Strength of materials data: metal and wood fixtures, 5 epoxies tested under water, plus controls

Samples air cured form the control group. All metal samples were degreased with mesh soap pads in hot water, dried, and then coated with epoxy.

Samples designated REF were prepared by applying the adhesive under sea water in trays on the lab bench and then moving the trays of samples in seawater to a refrigerator where they were stored for 37 days from Sept. 18, 2001 to Oct. 25, 2001 at a temperature of 44° F. The mixing of the two-part epoxies was done in air.

Samples designated SEA were prepared by applying the adhesive under sea water on the lab bench and then moving the wet samples to a wire cage and immediately submerging them in seawater outside, attached to the campus dock. The Bio-Fix 911 samples were left for 42 days from Sept. 25, 2001 at an ambient sea temperature of ~19° C and they were harvested on Nov. 6, 2001 at an ambient sea temperature of 13° C. The samples were kept wet until the time of the strength tests. The samples of Repairitquik, 10-3070, Fastweld 10, and Epoxo-88 were deployed for 55 days from Sept. 25, 2001 when the ambient sea temperature was ~19° C to Nov. 19, 2001 when the ambient sea temperature was 10° C.

Samples of PSI-326 (Smart Glue) were tested by mixing the two components in air on the lab bench. The epoxy was applied under seawater and the life testing was done under seawater off the campus dock for 19 days from October 18, 2001 when the sea temperature was 13° C to November 6, 2001 when the sea temperature also measured 13° C on the day of harvest. All temperature measurements were done at mid-day. The samples were suspended at a depth of about 1 meter below the surface. During the tests of PSI-326, it was discovered that the two components could be mixed under seawater, as well as applied under seawater. The adhesive applicators invented by the students take advantage of the ability to mix PSI-326 under water.

We note that there is no strong pattern of test results that depend on the fixture material. The peel strength was negligible. Our results suggest that more attention must be paid to the uniformity of the epoxy film and a greater film thickness would be beneficial. The most noteworthy result is that several adhesives that were applied under seawater formed bonds that survived life tests. The experimental data are found in Appendix I.

3. Other adhesives tested, adhesion to rocks under water

PSI-326, otherwise known as "Smart Glue", was the best adhesive. It is available in bulk and also in a one shot applicator. In bulk, it is sold as part A (resin) and part B (hardener). The mixing reaction of the PSI-326 is exothermic and the manufacture, Polymeric Systems Inc., recommends limiting the mix to one teaspoon. By adding glitter powder to the mix, the epoxy can be used as a marker. The best way to apply it is with a Q-tip or wooden stick. We found that we could bond etched glass, smooth glass, plastic tabs and nail heads to the sea rocks. However, the curing in chilled seawater was not optimal. Out of the other main adhesives tested, none of them except for the Smart Glue adhered to the sea rocks! The other adhesives were: Sta- Dri Hydraulic Cement, PSI-326, Clear RTV Silicone and Testco Paint Pen for marking. Hydraulic Cement did bond to rocks underwater, but not to plastic or glass. It is sold commercially to be used to stop water leaks in concrete foundations. We found that the cure time was too long to be practical for ALVIN use. Hydraulic cement came in powder form and was mixed with seawater to form a putty substance. We had expected good results with Clear RTV Silicone. Dr. Pocius of the 3M company believed it would be the best adhesive due to the fact it was permeable and was able to eliminate the film of water that was between the surface of the rock and the adhesive. We expected that the boundary layer of water would percolate through the adhesive, leaving nothing between the rock and RTV Silicone. This was proved to be false, however, because the surrounding water would not allow the boundary layer to escape. Bonding to a wet surface with RTV Silicone probably only works in air. The Smart Glue was the better bond to the submerged rocks.

4. Inventions of adhesive applicators for use underwater

The best adhesive is nothing without an applicator. This is why we have tried to develop one that will fit many criteria. The device would have to be reliable, so a simple design is an important aspect. As you can see in the diagram below, this applicator has no moving parts, and few individual pieces. It is made up of a single aluminum plate along with two sponges, and a triangular aluminum handle attached to it. These materials, along with being simple, are also durable and will withstand temperature changes.

One other consideration is that human hands will not be operating this applicator. We had to come up with something that could be operated robotically, using three fingers, and one arm of limited movement. This is of course referring to the mechanical arm of the submersible research vessel ALVIN. This applicator takes advantage of ALVIN’s ability to spin its three-fingered hand. Once holding the applicator, all the controller has to do is press it against the surface to be adhered to and spin. This is why the applicator’s pyramid shaped handle is utilized, taking advantage of its three vertical surfaces to grasp onto.

In addition to being simple, durable, and able to be manipulated by ALVIN, this applicator is also disposable. For this reason it can be left on the bottom of the ocean at no big loss, and is no threat to the environment. A CAD drawing of the applicator and a photograph of the prototype sponge applicator is shown below.

The second type of applicator, shown below, consists of two segments. Two corners of a plastic bag ("Baggie") are used, one corner with the resin, the other corner with the hardener. The ends of the Baggies are tied off with some twine. The Baggies are completely filled with one part in each of the corners. The Baggies are filled so no air bubbles will be present, which would compress because of the extreme pressure of the ocean at the depths that ALVIN will be working in. The Baggies are glued onto a hard rubber stopper. The rubber stopper is made out of material similar to a hockey puck. On the other side of the stopper there is a tee handle that ALVIN will be able to pick up with his robotic arm. ALVIN uses tools that have a tee handle built into them.

When ALVIN is ready to use the applicator, he will pick it up from his basket with his manipulator hand. While holding on by the tee handle, ALVIN will squish the Baggies and stopper against the rocks and rotate the stopper over 360 degrees, mixing both parts of the epoxy and applying it to the rock to be marked.

5. Unanswered puzzles, questions, and opportunities

In the course of the experiments we noticed that the first five epoxies tested would adhere to the metals as expected but would not adhere to rocks, either volcanic or granite. Dr. Pocius shed some light on this subject. One suggestion was that a weak boundary layer was created. That is to say that when the epoxy was applied underwater with no clamping pressure, a layer of water could have been trapped between the epoxy and the rock. This boundary could prevent the epoxy from fully adhering to the rock. Another suggestion of Dr. Pocius was the solubility parameters of the adhesive. Adhesives are attracted to like substances. So trying to bond a piece of glass to a rock, we might find that the adhesive sticks to one but not the other. A choice for adhering two items with mutual solubility would have the best results. The metal strips and oak wood would work because at the time of application, the slabs were squeezed together pushing out the water that would leave a boundary layer. The slabs were also joined together with like substances (wood to wood and metal to metal) that would resolve the problem of mutual solubility.

Another suggestion of Dr. Pocius was to use an RTV silicone. The reason for this suggestion was that the RTV silicone allows water to percolate through, displacing the weak boundary layer. However, RTV silicone proved unsuccessful. The cold water may have slowed down the cure time for the silicone (taking longer to harden or even by not allowing the silicone to harden at all). We came across this problem during one experiment using the RTV silicone by submerging the silicone cartridge into the cold water to simulate the decent of ALVIN into the depths and then applying it to the samples of rock, glass, and various other materials. We let the samples cure and checked the next week to see the progress. We found that the silicone did not cure. The RTV silicone allows water to percolate through, promoting curing when the wet surface is cured in air. When fully surrounded by water, the silicone may not be able to keep up with the amount of surrounding water and, therefore, still allowing a weak boundary layer of water to exist.

The epoxies may be used in other applications such as on seashells in aquaculture. Seed shells may be affixed to a wire to start a colony. This could be accomplished by taking a closer look at the surface structure of the seashells. This may reveal how well the epoxies will adhere. A rough surface structure would be better for the application of epoxies, creating more surface area for the adhesive to grip. Surface preparation is a critical part of the application of epoxies. Creating a surface that is rough for the epoxy to grip but not so rough that the epoxy can’t adhere to the entire surface or trap either water or air in the surface grooves. At a microscopic level, a rock may have a smooth surface and be hard for an epoxy to adhere to.

During the course of the semester, we tried several pre-manufactured applicators and also made our own applicators. We invented the applicators through a process of brainstorming and trial and error. Some pre-manufactured applicators may not be available empty, not allowing us to add the epoxy we find best suited for the task at hand. Thanks to Mr. Whalen, we know about a two-chambered applicator that is manufactured by the 3M Corporation. However, the tubes would have to be filled by us, with no air bubbles. Our best applicator designs were the double bag and the sponge type applicator

The best candidate for epoxies was found to be Smart Glue. We are not sure why this would be. Upon closer investigation of the Material Safety Data Sheet (MSDS), we found several chemicals to be the same in all of the epoxies we tested. When we looked at Smart Glue we found one ingredient, which was declared a "trade secret", and therefore the company would not disclose that information we were curious about.

Shown below is a photograph of a commercially available pre-loaded epoxy applicator with a two-chamber barrel for the resin and the hardener and a set of baffles in the nozzle to mix the components.

6. Conclusions and recommendations

Over the past semester, we have worked with numerous glues and epoxies. They all have their strong points: some stick better, apply easier, or wear longer. Finding the right combination was the key. In the end, Polymeric Systems PSI-326 (Smart Glue) proved to be the best choice for deep submergence work. To apply it underwater, new devices needed to be developed and tested. Two devices, an applicator using sponges, and another using Baggies of solution A and solution B, were constructed and tested. A

commercial applicator gun designed by the 3M company is also on the market.

 7. List of project participants; acknowledgments

Volunteer students from the Upper Cape Cod Regional Technical School:

Ann Bodio
Christopher Francis
Ashley Lafleur
David Landolfi
Mark Mancini
Christopher Marconi
Mike Mcgonagle
Ryan Murphy
Sean O’ Brien
Emily Russell
David Smith
Adam Thomas
Matthew Turner
Sarah Walsh
Jessica West
Mandy Westgate
S Chris Young

Prof. Ucci’ s Engineering class ETK59 class at Bristol Community College:

James Barbaria
Inigo Loyola
Paulo Medeiros
Taylor Michaud
Brian St. Rock
Channy Sypaseut
Paul Ventura
Steven Wheeler.

Cadets in Prof. Sichel’s Marine Adhesives class at the Massachusetts Maritime Academy:

Thomas Foley
Richard Holcroft
Tim Maguire
Brian McCormick
Timothy McQueen
Jonah Pike
Erik Sunde

We wish to acknowledge the guests that devoted time out of their busy schedules to help make some sense out of what we found. Dr. Maurice Tivey and Mr. Dudley Foster from the Woods Hole

Oceanographic Institution; Dr. Alphonsus Pocius from the 3M Company; and Chief Engineer Mark Whalen from Sippican, Inc.

This project is funded in part by the National Science Foundation.

8. Appendix I

Epoxy codes

88 = Epoxo 88 by Fasco Unlimited of Hialeah

911 = Bio-Fix 911 by Progressive Products, Inc.

RIQ = Repairitquik by Polymeric Systems, Inc.

FW = Fastweld 10 by CIBA -Geigy Corp.

3070 = Epoxy 10-3070 by Epoxies, Etc.

Date codes

010913 = Sept. 13, 2001, etc.

Cure codes

C or AIR = air cure control samples

REF = applied in seawater and cured in a lab refrigerator in seawater

SEA = applied in seawater and cured in seawater off the campus dock

Fixture codes

AL = aluminum shim stock

AH = heavy aluminum stock

SS = stainless steel

CS = mild carbon steel

Appendix II: list of adhesives

• Fastweld 10 (Ciba-Geigy Corp., 4917 Dawn Ave., East Lansing, MI 48823)
• Epoxo 88 (Fasco Unlimited of Hialeah, Inc., 7735 West 20th Ave., Hialeah, FL 33014-3227)
• Bio-Fix 911 (Progressive Epoxy)
• Epoxy 10-3070 (Epoxies, Etc., 21 Starline Way, Cranston, RI 02921)
• FastSteel and Repairitquik (Polymeric Systems, 723 Wheatland St., Phoenixville PA 19460-3394)
• PC-11 (Protective Coatings Co.)
• ACE 10232, store brand (Ace Hardware Stores) Water-proof epoxy putty
• Smart Glue^R When sold in bulk, product name is PSI-326. (Polymeric Systems)
• Sta-Dri hydraulic cement (Sta-Dri Co.)
• Permatex Black Silicone Adhesive/Sealant (Permatex, Inc. product #81158)
• Clear RTV silicone (Permatex, Inc. product #66B)
• BoatLife Calk (sic) (Life Industries Corp., Charleston SC, product #1030)
• Testco paint pen for marking (Testors Co. product #2503C)

Appendix III: strength test results for PSI-326