Anybody have any luck bonding polypropylene ?
11-25-2014, 09:53 AM
#1
Anybody have any luck bonding polypropylene ? I'm working on a custom bumper project that's fairly complicated, and it involves some repair/bonding of polypropylene. PP/EPDM to be specific. I know I can plastoc weld this stuff to some degree, but a lot of the project requires dissimilar materials like urethane and steel to be bonded to the polypropylene so I need something (or a procedure) that really sticks well.
Things I've tried:
3M 5887 EZ sand flexible parts repair- this stuck pretty good when using 3Ms 5907 adhesion promoter. It's pretty soft though to be used for bonding, but I'll probably use this all over the top side.
3M 8239 TPO plastic parts repair- this stuck OK with the same AP. I could still twist apart the two test pieces fairly easily.
3M 8223 Universal adhesive- this is the winner so far. I'm not sure if it's fit to be used anywhere that will ultimately be visible due to its expansion rates vs the urethane/polypropylene, but this is what I'm gonna use unless somebody else here has a better idea.
SEM 39767 problem plastic- it was ok. Other than the color it was similar to the 3M 8239 but the 3M definitely stuck better.
3M scotch-weld DP8010- this stuck fuggin awesome without the adhesion promoter, not so much with. It's non-automotive industrial stuff though, and it is really stiff when it's hard. Not something I want to use on flexible parts.
3M 4247 super fast plastic repair- this stuff is the bomb when it comes to plain old urethane like what's on an Fbody. Pulled apart pretty easy with polypropylene. This is the same thing as 4747 , just in a bigger tube.
I've tried all the above with both the 3M adhesion promoter, and Lord Fusor's AP as well. They work the same for me.
The problem is that polypropylene has wax in it, and when you sand it you're introducing more wax to the surface. I had best results when sanding with 80, skimming with 180 afterwards, then cleaning with rubbing alcohol. Then I washed the parts with a tiny amount of dish soap and scrubbed the sanded areas with a scotch-brite pad until water didn't bead anymore. Then I let them air dry in front of a fan, wiped with alcohol once more, sprayed the adhesion promoter, finally used the adhesive once that dried.
Most of that stuff sticks ok, but not really bonded if you know what I mean. You can take the two test parts and twist them back apart in your hands with moderate force even after a full cure. In contrast, you can bond a urethane Camaro / TA bumper back together with any of the above, or 8237 is my favorite, and the car can get in a collision in the repaired area and the bumper will rip somewhere else. Urethane is awesome in this regard, it's just not as infinitely recyclable as PP/EPDM is so the OEs are all switching to it if they haven't already.
Any other fabrication junkies have better luck than me with this stuff?
Things I've tried:
3M 5887 EZ sand flexible parts repair- this stuck pretty good when using 3Ms 5907 adhesion promoter. It's pretty soft though to be used for bonding, but I'll probably use this all over the top side.
3M 8239 TPO plastic parts repair- this stuck OK with the same AP. I could still twist apart the two test pieces fairly easily.
3M 8223 Universal adhesive- this is the winner so far. I'm not sure if it's fit to be used anywhere that will ultimately be visible due to its expansion rates vs the urethane/polypropylene, but this is what I'm gonna use unless somebody else here has a better idea.
SEM 39767 problem plastic- it was ok. Other than the color it was similar to the 3M 8239 but the 3M definitely stuck better.
3M scotch-weld DP8010- this stuck fuggin awesome without the adhesion promoter, not so much with. It's non-automotive industrial stuff though, and it is really stiff when it's hard. Not something I want to use on flexible parts.
3M 4247 super fast plastic repair- this stuff is the bomb when it comes to plain old urethane like what's on an Fbody. Pulled apart pretty easy with polypropylene. This is the same thing as 4747 , just in a bigger tube.
I've tried all the above with both the 3M adhesion promoter, and Lord Fusor's AP as well. They work the same for me.
The problem is that polypropylene has wax in it, and when you sand it you're introducing more wax to the surface. I had best results when sanding with 80, skimming with 180 afterwards, then cleaning with rubbing alcohol. Then I washed the parts with a tiny amount of dish soap and scrubbed the sanded areas with a scotch-brite pad until water didn't bead anymore. Then I let them air dry in front of a fan, wiped with alcohol once more, sprayed the adhesion promoter, finally used the adhesive once that dried.
Most of that stuff sticks ok, but not really bonded if you know what I mean. You can take the two test parts and twist them back apart in your hands with moderate force even after a full cure. In contrast, you can bond a urethane Camaro / TA bumper back together with any of the above, or 8237 is my favorite, and the car can get in a collision in the repaired area and the bumper will rip somewhere else. Urethane is awesome in this regard, it's just not as infinitely recyclable as PP/EPDM is so the OEs are all switching to it if they haven't already.
Any other fabrication junkies have better luck than me with this stuff?
11-26-2014, 11:36 AM
#2
I feel your pain with the PP. 3M dp8005 is the only thing Ive used that will actually bond pp. It is made for low energy plastic. I do alot of interior fabbing and alot of OEM's have went to PP or reinforced pp over abs, so this stuff is a godsend.
I have not used it with dissimilar materials though, only pp to pp. I don't envision it being a problem though as once your outside the realm of low energy plastics a wide array of epoxies will bond, I would verify with 3m though.
I have not used it with dissimilar materials though, only pp to pp. I don't envision it being a problem though as once your outside the realm of low energy plastics a wide array of epoxies will bond, I would verify with 3m though.
11-30-2014, 10:03 PM
#4
TECH Enthusiast
Doing the Camaro nose el camino project in late 2009, welding is the best to stand up to the test of time .All my welds are holding up really good,what little bit of (glue) I used is showing up now through the paint.
You may be able to glue 2 dissimilar plastics together, but they WILL show a shadow later. What I'd recommend is get extra plastic of the same exact type. It can be reheated, reshaped , welded, etc. I used wood forms on 2 sides to shape some parts & to hold shape on bumper sides while welding mounting flanges on sides, I used mostly an LCD controlled hot air gun & ribbon strips on each side of welds. Plastic doesn't molecularly cross bond on welds, so the backside should be mad thicker to compensate. Made some of my own ribbon strips from donor material. Got by bumper fascia & extra stuff from a bumper recycler. pp/edpm is pretty much the same as the teo plastic I worked with.
You can melt wire grid into the backside & weld on 90 degree tabs or what not on the backside.
Check out urethane supply company. They had some type of stick material that would bond to most anything.
Flame treating is another method sometimes used before bonding to plastics.
here's a picture of what my welding looks like nearly 4 years after being done.
Can you give me more details as to what brand and year main part you are using & what you're trying to do? Many told me what I was doing wouldn't look right or work.
You may be able to glue 2 dissimilar plastics together, but they WILL show a shadow later. What I'd recommend is get extra plastic of the same exact type. It can be reheated, reshaped , welded, etc. I used wood forms on 2 sides to shape some parts & to hold shape on bumper sides while welding mounting flanges on sides, I used mostly an LCD controlled hot air gun & ribbon strips on each side of welds. Plastic doesn't molecularly cross bond on welds, so the backside should be mad thicker to compensate. Made some of my own ribbon strips from donor material. Got by bumper fascia & extra stuff from a bumper recycler. pp/edpm is pretty much the same as the teo plastic I worked with.
You can melt wire grid into the backside & weld on 90 degree tabs or what not on the backside.
Check out urethane supply company. They had some type of stick material that would bond to most anything.
Flame treating is another method sometimes used before bonding to plastics.
here's a picture of what my welding looks like nearly 4 years after being done.
Can you give me more details as to what brand and year main part you are using & what you're trying to do? Many told me what I was doing wouldn't look right or work.
Last edited by jlcustomz; 11-30-2014 at 10:54 PM.