THIS IS THE POST TO READ IF YOU WANT TO KNOW SOME DIFFERENT REPAIRS.
I had an autobody shop for years and many expensive plastic panels get repaired.
Many different plastics: TPO, urethane, poly's, SMC. I think that is SMC which stands for sheet moulded compound.
Plastic weld - you need to preheat the area, a good welder, the same composition plastic rods and know what your doing. So this method is probably out.
The easiest fix is Eternabond tape (eBay) on the inside. A double layer will hold it together. Coarse wire 1/2" mesh between layers gives some strength. Every home should have a roll of Eternabond. I just fixed my kayak and that was TPO; the hardest to fix.
A good fix is PC7, or JB weld, or Devcon, or something similar. BUT YOU MUST CLEAN SPOTLESS AND WIPE WITH RUBBING ALCOHOL THEN APPLY A CONVERSION COATING TO THE SURFACE SO THE EPOXY STICKS. A spray plastic etching primer will adhere to the plastic and the epoxy will stick to that. It helps to drill some anchor holes about 1/8" size around the crack. Wire mesh or glass matt also strengthens the repair but you must spread out all air from the repair area. Double layer repairs are better.
Touch up the 1/8" anchor holes on the outside when done. Razor blade what oozes out on the good side before completely set up.
I took 8 hour classes on this so giving you the short course. But this should get u by.
