I am fabbing up a project and using TREX as a semi non structural element. I’d like belt and suspenders so I called a good buddy here at BT and we hashed the various adhesives around. we concluded a call to TREX may be wise, so I did.
It appears that Gorilla type polyurethane is the factory recommended adhesive, when I queried the woman I spoke with, I mentioned the observation that TREX is recycled PTFE plastic, the same polymer as milk jugs AND GLUE BOTTLES..
Whats not gonna stick?
So…if you were gonna glue trex to itself, would you opt for a filling glue like PL thick or a film like PL thin ( gorilla) or a chemical bond like Azek?
Just for gits and shiggles I made up a few test joins with thin and thick..I don’t like either so far..the trex is repelling the glue somewhat.
Jer mentioned the scarifying of the join for tooth, I’ll be on that, but it seems to me that thermo welding is the best option when playing with these polymers..or maybe a cyanoacrylate?
weigh in please..I’d like to have the knowledge for future use, I have not used this stuff in this fashion, and would hate to FU on my cherry pop.
Spheramid Enterprises Architectural Woodworks
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Thermowelding is what is used on PE pipes such as the inground loops for ground contact heatpumps.
Is M. Hussein S. the BT that you talked to?
I know that he uses Trex for window trim.
William the Geezer, the sequel to Billy the Kid - Shoe
No, I'd not ask the Rev. Mike WHOISANE Smitty anything, he's a Dweeb..LOL.
I did call Jer whom I have boyish crush on, for his advice..I like Jer, he's gentle.
Anyway..it seems if I was gonna go ballistic and wanted a really strong fusion, it can't be had. Thermo ( tried with my 1000Watt ele iron) fails, too much fiber...PL fails..too little fiber for the urethane to grab, and too little moisture retention.
Again PVC solvent wont touch PTFE..what does? I have MEK and it just sits there..I'm thinking PTFE is just impervious to chem welding.Spheramid Enterprises Architectural Woodworks
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Due to its extremely high resistance to solvents as well as its anti-adhesive properties, PTFE can only be glued or adhesion-bonded to other materials after the respective bonding surfaces have been properly prepared. There are various techniques known for this purpose. In addition to wet-chemical activation with sodium and ammonia solutions, plasma treatments of PTFE surfaces have been successfully used.
http://www.elringklinger-kunststoff.de/pages/article/article_0601_e_konstruktio.html
Damm, I was typing to Bill as you posted..that's what I thought.
Gotta find a meth lab to make a cupola..that makes sense.
ThanksSpheramid Enterprises Architectural Woodworks
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I believe you meant LDPE (low density polyethylene) not PTFE (poly tetra fluoroethylene - teflon-)
Don
I believe you are smarter than I am, and quite possibly more righter.
Now what? (G)Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
They kill Prophets, for Profits.
I believe you are smarter than I am, and quite possibly more righter.
Now what? (G)
Being right is all that's important to ME :)
I'm by no means an expert - we just use a few different plastics for fixtures, etc. in various parts of our manufacturing processes.
I seem to recall one of our other engineers having to do some bonding of either high density polyethylene (HDPE) or ultra high molecular weight polyethylene (UHMW). As Mongo mentioned, heating the surface was the first part of the process. Then, it was either an epoxy or cyanoacrylate glue, from 3M or Loctite, I believe, which was recommended for this application. I couldn't open DanH's 3M link - maybe that was it.
The adhesive was pretty expensive, though - wasn't bad for a small fixture, but maybe prohibitive for your application.
Don
http://multimedia.3m.com/mws/mediawebserver?66666UuZjcFSLXTtnxfVmXs6EVuQEcuZgVs6EVs6E666666--3M also has sticky tapes that may be a good choice for this material.
The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel
Polyethylene is tough to glue, as it's a long molecule. We can get into the structure of the polymer, regarding functional groupings on the molecule and how stable it is as a molecule, but what it boils down to is that PE is not easy to glue.
There are solvents like some ethylene monomers, but even that won't prepare the material to be chemically welded in real-world applications. It's just not practical.
Best bet it to heat-treat the surface. That works on PEs, though I've never done it on Trex. A few light passes with a propane torch helps to get rid of some of the slickness on the face of the material. On a microscopic level think of it as burning off surface contaminants like surfactants, plasticizers, or other things in the PE that are left over from the extrusion process. You're not looking to melt the surface...just think of it as a heat treatment of sorts.
Another alternative has already been mentioned...scarifying the surface (belt sander perhaps), then glueing.
Typical adhesives would then be those already mentioned...urethanes like Gorilla, epoxies like West Systems, or water resistant PVAs like Titebond II.
But in no way would I consider any of these adhesive-only bonds to be structural.
All those polymer courses I took in collij...whoda thunk I'd remember any of it.
This is not scientific at all and you obviously know more technical about this stuff than me, but here is what I've found:
On some of my spec houses I wanted a little better looking front steps than just PT or concrete so I used Syymatrex for the treads (made by DOW, I think no longer made). I assume this product is similiar to Trex. I just glued them down with PL adhesive and tacked with 15 or 16 g finish nailer to hold it untill the glue set up.
To test, I glued a couple pcs. together and let them sit about a week, at that point I could still get them apart, then I re-stuck them (no additional glue) and left it in the shop for probably a month. when I then tried to get them apart I had to use a prybar and the syymatrex broke! The glue bond held! The syymatrex did have a small amount of "tooth" to it naturally, but not a lot. I also was very generous with the amount of PL I used.
I know this is not an "approved" method but it worked for me
Edited 1/7/2009 2:06 pm ET by LIVEONSAWDUST