On Tuesday, April 14, 2020 at 9:07:42 PM UTC-7, Mike S wrote:
I have Skullcandy Crusher headphones and the hinge plastic broke. It's a
really common problem with them. I don't need a hinge, I'd like to epoxy
the hinge joint in the fully open position as it would be when being
worn. I tried using 2 part epoxy to hold it together, but it wasn't
plastic rated epoxy and it held perfectly for about 4 minutes, it was
easy to pry off of the plastic and it was clear it didn't adhere well at
all. I remember making plastic model cars and planes as a kid, the glue
seemed like it melted the plastic pieces into one another for a really
good joint, like a weld in metal. I don't know what grade the plastic
they used for the joints is and I don't know how to find that
information. Is there an all purpose adhesive or epoxy that I can use to
make one big solid mass of plastic? Or do I pretty much have to try the
various adhesives used for different grades of plastic?

This amazon ad says

Loctite Super Glue Plastics Bonding System with Activator 2-Gram (681925)

Bonds plastics such as Plexiglas, polycarbonate, polystyrene, PVC,
polyethylene, polypropylene and polytetrafluoroethylene (PTFE)/Teflon.
Plus rubber, leather, cork, paper, cardboard, wood, chipboard, fabric,
metal and ceramic.

https://www.amazon.com/Loctite-Plast.../dp/B000Y3LHXW


Loctite sells 2 different adhesives for these two different types of plastic

The easiest way to identify a plastic type is by its label, commonly a
recycling symbol. Plastics marked with a 6 or €œPS€� are polystyrenes.
These are used for simple items like disposable cutlery, plastic bowls,
or fashion bags. For these, the best glue is a poly cement such as
Loctite Plastic Bonder.

Other types of plastic are used for tougher industrial or construction
uses, such as drainpipes. Special plastics are even used for medical
applications and bulletproof vests. For gluing these plastics, try
Loctite Plastics Bonding System, which creates a powerful bond with just
one drop.

https://www.loctiteproducts.com/en/k...stic-glue.html


JB Weld PlasticWeld comes with this note:

While this product works beautifully with most varieties of plastic,
please be aware that there are certain types - including polyethylene
and polypropylene sheet - that it will not adhere to.

https://www.acplasticsinc.com/inform...s-for-plastics

I use Weld*On products with lexan and acrylics. It is a solvent as you describe. I imagine that they have products for your plastic. https://weldon.com/

Good luck.