PVC plumber’s cement is essentially a solvent that dissolves the plastic it contacts and when the solvent evaporates off, it leaves the two plastic parts welded together. Plexiglass (acrylic) turns into goo if lacquer thinner or something similar contacts it and so it’s a good candidate for solvent welding.
Plastics that can’t be solvent welded include polyethylene and it’s cousins. HDPE (high density polyethylene) and PEX, (cross linked polyethylene).
Nylon, Polycarbonate.
HDPE can be welded with heat using a scrap piece as a filler rod. Just light the filler rod like a candle and drip the molten plastic onto the joint you want to weld.
