The original title of this thread was 'Plastic Model DeBonder' but was very misleading. No matter how much you try you can NOT debond plastic glue because there isn't actually any glue to debond.
Plastic glue is better thought of as plastic 'weld'. It works by melting the top surface of the plastic it's in contact with, evaporating as it dries. Components glued in this fashion literally melt into each other and solidify into one cohesive piece.
Your only real option in the case of good plastic glue is to cut the joins apart. This tutorial refers to Cyanoacrylate (Superglue/Krazyglue) debonder.
I was down at the local hobby store (it's an art store with military models) and I needed some more gap filling plastic glue. I stumbled through their glue area, (tripped really,) and came face to face with this product on a lower shelf.
I bought it took it home, found an Ebay-bought Leman Russ that I had soaked in Simple Green and stripped it, but the owner must have been blind and used three tubes of superglue to put it together (think ball of glue with a cannon sticking out).
I though "what the heck" and tried this little bottle of green-labeled "magic" and the model practically FELL APART at the seams! I was floored. Some of the more sturdy glue joins had to be worked (score with xacto knife then work the pieces back and forth) just wipe the excess off and dry the models once the pieces are free.
The glue turns into a non-plastic water base, and the pieces come clean apart without melting or warping.
I had some Dark Angels I had accidentally glued to bases, and wanted them off to paint and to pretty up the bases, and squirted this stuff on them, and did not wipe the excess off, the plastic turned WHITE. The debonder dried, leaving a strange stubborn white powdery residue, and turned the plastic underneath white so be warned...wipe down the excess once the pieces are free, or better yet, dunk them in water and neutralize the chemicals.
I glued my fingers together by accident, watching women in bikinis on TV while glueing my Blood Angels together,...and I used this stuff...BAM! free fingers..wipe clean, wash hands..good as new..no biting off the glue!!!
It de-bonds any glue that has that Cyanoacrylate stuff that the modelling and super glues have in them.