Front bumper material?
 

What is our front bumper made of? I picked up a front bumper that is cracked but relatively easy to repair.

Polyurethane?

Haven't had mine off, but just about every car on the market in the past 10 yeasr has had polyurethane bumpers. i can't imagine ours is any different.

If it's poly it's the most brittle poly in the history of poly. They break really easy.

You aren't supposed to repair a cracked bumper.

Not talking the steel crash bar. The plastic cover. Figured it was polyurethane but wanted to be sure.

Thanks guys!

Old thread but was trawling the forums looking for this information because I'm in the process of making some repairs myself. I though it was worth making a correction:

The bumpers are made out of polypropylene (PP). It's clearly stamped on the part (this type of material information can be found stamped on almost every plastic part on the car.)

Knowing the bumper is made of PP is critically important because it's a Low Surface Energy (LSE) material: most adhesives/epoxies/glues don't work on it, especially if you need the repair to be strong and hold load.

There are specialized structural adhesives out there that are made to work with PP, but you need to know what to look for AND they tend to be expensive (3M DP8005 / DP8010 and Infinity Bond MMA 500). Your budget option is to use a primer (like Loctite 770) and cyanoacrylate glue (i.e. super glue) BUT usually a repair like this won't be strong unless you have a really close fit and get it put back together with precision.

On the other hand, PP lends itself very well to plastic welding. I've repaired several household items with a cheap soldering iron and some doner PP (from plastic jar lids). Using a purpose made plastic welder should work much better.

Decided to try using plastic welder for one of the repair tasks (rebuilding a completely lost tab). Worked pretty well with an Amazon soldering-iron-style kit. My first time doing a plastic weld. Intimidating at first and a slight learning curve but the end result was satisfactory and strong. Soldering and welding principles are key (as well as good ventilation) - maintaining material wetting/flow to get a proper fuse is a must. It pretty much needs to be formed continuously which can be challenging as you add more and more material. If you just add more material on top gradually - like dolloping play dough - the layers don't bond and just snap when you bend it.

Splurged on 3M DP8010 for other tasks. Amazing stuff: a strong bond even across a thin edge glue line. Used it to glue back the fender liner bolted tab that got snapped-off completely (red damage circle). I went back afterward and reinforced it with a single sheet of fiberglass soaked in the same adhesive to provide some additional strength against flex/peel mode.

Finally it's worth nothing that DP8010 (and other similar adhesive) isn't good for repairs that have very close clearance and where you can't bring the parts together to trap the adhesive in between (e.g. a slip formed by a thin crack, green damage circles). The adhesive is pretty thick and you end up just squishing the adhesive out of the gap, leaving barely any to make a bond. For these cracks, I ended up using Loctite 770 Primer with Prism 401 superglue which wicks extremely well and forms a strong bond. Hoping the tightness of the fit will help the joint hold up to flexing over time, but we'll see. If it doesn't hold, I'll go back and plastic weld them with steel mesh.