Hey guys,
I purchased some strong plastic-bonding epoxy to fix the lower part of my split front bumper, but have also used it to adhere some small ABS plastic pieces to the sides of the top of the power headrest slider/regulator before the white plastic splits completely through due to stress/age. I’m just noticing now that the package of the epoxy says that it does not bond to polyethylene and polypropylene. My question is, is the white plastic regulator made out of either of those two plastics or is it just white nylon? I’m hoping nylon :-)

Polyethylene and polypropylene have low surface energy so glue won't stick very well. PE and PP are waxy plastics used for milk jugs , battery cases and a bunch of other low strength requirement applications.

Have a look at these two places for plastic ID. ( I didn't look through the first one , the second should still have info. )

This company used to be called USC ( Urethane Supply Company ) but sold a division to Valspar and changed the name to U.S. Chemicals and Plastics U.S. Chemical & Plastics .

The original USC is now called https://www.polyvance.com/‎ ( yep, I know odd name given they have been known as USC for along time )

Well, that white plastic headrest slider/regulator is definitely either polyethylene or nylon, because the thin pieces of plastic I epoxied to the sides of the top head part peeled right off. I ended up buying this special Loctite glue/prep kit that works specifically with polyethylene and polypropylene. I had purchased a used slider from the wrecker, but it already had a hair-line crack in the usual place on the top. So, to reinforce it, I scored both sides of the plastics being mated together and applied the activator and then the glue, then pressed the pieces together. Seems to be holding now and the head rest is now installed and working once again. I am mindful to mention to people sitting in the car not to lower the head rest all the way down because that's what seems to make them crack due to the pressure.