Does anyone know what type of plastic the interior plastic panels are made out of?

I am buying a set of rear bins that are in rough shape and need some plastic welding/patching to repair some cracks and gouges. I'd like to do the strongest plastic weld possible when repairing them using the right plastic type. I assume it's likely a common type plastic like ABS, polyethylene or polypropylene but I'm unsure.

Any help would be greatly appreciated.

 

All the interior panels are slightly different plastics. They should be stamped on the underside with what type of plastic it is.

Dale

 

I used to have a really good link from DuPont that had several easy methods to figure out what kind of unknown plastic you're dealing with, but it appears that link is dead now. So after a quick google, I found this Youtube video that might be helpful -
Probably better content out there, but it's a start. It's mostly info on a plastic welding kit they sell, but the first few minutes show a few tests you can do to figure out what kind of unknown plastic you're dealing with. The tests all require taking a small sample of the plastic - there are float tests and burning tests, where you burn the plastic and observe how it burns/melts/smokes/smells, etc.

 

Plast-Aid has worked better than anything else I've tried.
https://www.rx7club.com/3rd-generati...w-pics-828143/

 

I think the rear bins are a polypropylene. Somewhere on the plastic with other mold marking will be PP. I saw this because they are flexible and have a wax like feel when scratched. PP is "weldable" but takes practice. When manufactured, they you a mold release that tends to stay on the top later. I found one way to remove it it a lightly touch it with a propane flame. You will see it ever so slightly flash off. Follow up with acetone but don't let it get over everything as it leaves a white film sometimes. FYI, this will not leave a nice finish, so work from the back side.

 

Lots of really good information here, thanks guys.

Looks like there is a bottle of Plast-Aid in my future for the broken tabs and some very patient plastic welding for the cracks.

As for the plastic type I guess my best bet is to hold off until I have the bins in hand and see exactly what they're stamped with.

 

Don’t use the plasiti aid on polypropylene though. Won’t stick. There was another product someone mentioned that did work on polypropylene in my thread mentioned earlier. I haven’t trying that product though.

 

Good to know. I'll wait til the bins show up and confirm the plastic type before buying.

Hopefully swapping out the seats for bins won't be too much of a chore but seems pretty straight forward from what I can tell.

 

I can say from experience that JB Weld (the 2 part grey stuff) will adhere very well to the bin plastic.

 

Bit of advice: When it burns, Polypropylene reacts with Nitrogen found in air to form Hydrogen Cyanide gas. You do NOT want to breathe this, so do any plastic welding in a well ventilated space. Also, plastic welding most thermoplastic is pretty easy with a soldering iron. I've done so on a Fuse box cover that was made of a mix of Polypropylene and Polyamide (Acrylic) using a 180 watt soldering gun. As long as the parts fit well together before welding, it'll generally go fine. The best method I've found is to "tack weld" the pieces together by pressing the tip right where the two pieces come together. Just press the tip into the seam until it starts to sink in about 1-2mm, then pull it back up. Repeat every 1/2 inch or so along the whole seam. Flip the piece over and repeat for the other side, placing your tacks between the first ones.

If it is difficult to access the other side, you can press the tip in further, even going all the way through but it means more work to make it look good when you're done. I prefer this approach because full penetration makes a far stronger weld.

Having some filler material available makes this a lot easier when going over it to clean up the seam. There are two things to remember for this.
1. Material will go towards the heat source.
2. You can use the heat source like a paint brush to move existing material around to fill holes.

Overall, the process is to Tack, then run the iron along the seam to close the openings from tacking. Last, pass the iron diagonally in an overlapping cross-cross pattern across the seam to smooth it out and fill in any low spots using material from any high spots. That should get it all down to one relatively uniform level. Any remaining high spots should be minimal and can be flattened out with some sandpaper. Then apply whatever paint or rubberized coating that suits you.

 

Thanks for the heads up, I didn't know specifically what sort of gas it gives off but I have exhaust fans going and the door open any time something is burning in my garage but that'll be enough to make me throw on a respirator as well.

The piece looks like it fits together tight in the main crack I'm worried about, to the point where you can't see it unless pressure is being exerted on the piece. I think the plan is going to be to sink a wire mesh into the plastic reasonably deep to get good penetration and build back on top of that a bit with a polypropylene welding rod and plastic welder. Between the mesh and added material I think it should be plenty strong. At this point I'm more concerned about building back the broken and/or missing tabs. I can't imagine they're under much stress when in the car but I could always fab something up out of an 1/8" aluminum flat. That seems like it is probably overkill but certainly doable.

Hopefully I'll get it mended in one day and then prepped and painted on another day since my dye idea was thrown out the window when I found out it was polypropylene. The things I'm doing just for a battery relocation is beginning to feel a bit silly but should be a decent project.

 

This stuff is good too. It also comes in black.