Depending on the type of plastic it is you may be able to solvent bond it. The problem is, you'll need some MEK or acetone to test the part. If the solvent melts the plastic, just soak both sides with solvent then clamp together for 4 hours.

Otherwise, just use a good two part epoxy. If you have room you might put a couple of plys of some fabric(glass preferably) on the bond line, like a band aid and soak that with the resin. Sand, clean first.

please tell me about the second advise, ı couldnt understand what u mean...

epoxy does not adhere well to plastic or glass in the presence of water or acid.

If the plastic part can be made sticky with one of the solvents he mentioned, that means the solvent is penetrating the matrix and two such parts can be wetted with that solvent to make them stick and then clamped together until the solvent evaporates, which might take a few days for strength.

Common silicone sealant from Dow corning, sold in hardware stores, is water and acid proof and adhered to plastic. It is not as strong as epoxy.

suggest he experiment

As LYNLYNCH had rightly suggested the two component epoxy adhesive should fit your need.

The other option could be the use of phenol formaldehyde resin in spirit solvent, which gets dried after pasting.

The resin ,solvent ,catalyst system used for FRP coating also should find use for your need ,since the FRP coating is meant for ACID corrosion proof coatings.

Coming to the second part of post 1, he means thorough surface cleaning prior to adhesive application to get firm bonding and the use of TWO component EPOXY adhesive using mixtures[ ready made individual tubes supplied in a single pack]. One such commercial name is ARALDITE and HARDENER usually available in electrical and hardware shops.You got to mix Araldite and Hardener in equal ratios till getting A WHITE PASTE AND IMMEDIALTELY apply to prevent hardening of the glue followed by longer air drying or heat curing.