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#3331803 - 04/02/14 09:38 PM Solvent welding advice needed
sipman Offline


Registered: 05/27/12
Posts: 11
Loc: philly
Hi,
I have a 83 vw rabbit that some of my trim pieces have cracked. I experimented with Solvent welding using PVC Cleaner. This cleaner is Acetone and M.E.K. It worked great! I used metal Duct tape to hold the two pieces together. The nice side of the trim has a leather like texture molded into the plastic. The solvent went through the crack, and it appears it dissolved some of the adhesive and redeposited it onto the plastic.
SO needless to say, the crack is still visible. Do you think if I used a hot glue, or perhaps silicone caulk, I could seal the nice side so that the solvent doesn't find the adhesive? Will the Acetone and M.E.K. dissolve the hot glue or the silicone?

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#3331840 - 04/02/14 10:19 PM Re: Solvent welding advice needed [Re: sipman]
JimPghPA Online   content


Registered: 08/22/09
Posts: 2830
Loc: Pittsburgh,PA U.S.A.
To weld plastic with a solvent use THF.

To glue plastic use Loctite E-20HP or E-20NS. The NS stands for no sag, meaning it will not run. You will require the dispensing gun. You can get the epoxy and dispensing gun from McMaster-Carr.

To heat weld plastic use a hot welding set made for plastic.
_________________________
Boy will I be happy when ALL vehicles on public roads are autonomous.


JimPghPa


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#3331846 - 04/02/14 10:23 PM Re: Solvent welding advice needed [Re: sipman]
robshelton Offline


Registered: 07/10/09
Posts: 449
Loc: Winston-Salem, NC
I've had good luck using pvc/cpvc pipe cleaner and solvent weld cement. But you need to be sure and not get any that has a color on the label. Not purple, etc. Sometimes you will need to bond a small piece of flat plastic behind the break to help support it if the material is thin. That is if there is room for it.
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#3331852 - 04/02/14 10:28 PM Re: Solvent welding advice needed [Re: sipman]
sipman Offline


Registered: 05/27/12
Posts: 11
Loc: philly
What would brand name for THF be? I like using stuff I can walk out a store with, vs having to start an account with.

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#3331860 - 04/02/14 10:43 PM Re: Solvent welding advice needed [Re: sipman]
JimPghPA Online   content


Registered: 08/22/09
Posts: 2830
Loc: Pittsburgh,PA U.S.A.
THF is sold in big drums. Any decent plastic molding company will have it. It is hard to keep in small bottles because it evaporates way to easy. It also has very low surface tension so it is easy to spill. I got some from a local plastic factory that does vacuum molding. I was there to discuss a project and we got to talking about glues, they gave me a little bottle of it for free, but they first gave me a print out of the MSD for it. I did a test by using it to weld two pieces of plastic together and then put the plastic in a clear oil. Those pieces have been sitting in that clear jar of oil for about a year now and they are still well joined.

Other than getting THF from some plastic factory I don't know where to send you to get some. I did not see the drum but they said they buy it by the drum. Probably 55 gallons.
_________________________
Boy will I be happy when ALL vehicles on public roads are autonomous.


JimPghPa


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#3331861 - 04/02/14 10:45 PM Re: Solvent welding advice needed [Re: sipman]
JimPghPA Online   content


Registered: 08/22/09
Posts: 2830
Loc: Pittsburgh,PA U.S.A.
BTW even with the cap on correctly, the small amount of THF I had managed to evaporate.
_________________________
Boy will I be happy when ALL vehicles on public roads are autonomous.


JimPghPa


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