Plastic Bonding

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One afternoon after a hard landing of my Hi-FORCE just at the middle of the runway at the airport where I work, one of the fins was damaged, broken at the middle of the root. Fortunely, the fin was just loosened from the "finlock." I tried super glue, it did not work, then I tried diferent kinds of epoxy, but nothig works because I have to maintain the original width of the root to be able to inset it back into the body tube. Then after a dinner with my friend showed me an acrilic, that in fact is design for dentist work and is made in two parts, a "Polymer" powder and a "Monomer" liquid, very fast in dry time. The product is called "Nic-Tone" and can be purchased from dental supply stores.

I tried it by just filling the crashed joints with the powder, then putting just few drops of the liquid on, and finally a little bit of more powder. I waited for 10 minutes and sanded the external surface After 20 miutes, the root looks and feels like one piece. I put in on the finlocks with the thought of applying the normal preasure to lock it in place, and thinking that if it breaks it again I have to replace with a new fin. To my surprise, it locked perfectly!

Then I tried a test by pulling hard on the fin. What I got was the fin out of the finlock again, but in one piece. Then I put it in again, no problem, it is like new.

Now I when I was building my new PML 4" Endevaur that has Quantum Tube, when I reach the step of the outer fillets for the fins, I try the same product, praying that the monomer liquid doesn't melt the quantum tube. Again to my surprise, it works incredably well, as is vey fast drying and the fillet was bonded to the tube making literatly one piece. It is also sandaable enough to give it good finish with 250 grade sand paper.

Then I was very interesting in know how strong and how heavy is this. I made two identical blocks, about one inch by 1/2 inch by 3 milimeters. One made with Devcon 30 min. epoxy and the other with this adhesive. I let them dry for 48 hs. and here is what I found: The acrilic one weghts 70% of the epoxy one.

Putting both on a gauged press at one end and holding the other end (to try to break it at the middle), the epoxy one broke at 79 pounds of pressure and the acrylic bends a little at 130 pounds and breaks at 136 pounds.

Then I got some material fvery similar to QT, and is exellent to fill holes. I filled one sq. inch and it looks like one pice. I think is a good product. Sometimes you have to look for somethings that works, even though it's not specifically for rocketry. And sometimes this results in a great discovery... like this.

Submitted by: Gustavo D. Piņero


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