Only clean it well with paint thinner (mineral spirit). Maybe sanding with 600 sandpaper will help a little too. I found sanding the surface with 80 grid paper helps gluing it with CA - no flame flushing needed. BTW another tip for using CA for gluing coroplast - this was proved to be the strong bond, it will tear the coroplast not the joint.

Here is the tip. Prep both surfaces with 3 steps:
1. Clean with mineral spirit
2. Run woodpecker
3. Rough with 80 grid sandpaper

Put small drops of medium CA every 1/2 - 3/4 inch. Press it and do not move it for at least 10 minutes. Do not use kicker, water or anything that supposed to speed up. Usually I let the glue set overnight.

When gluing wood to coroplast (plywood or balsa) I use the same prep for coroplast. For places, that will not work hard (in example servo tray) I skip woodpecker step.

One more information. When I use Gorilla glue with coroplast the surface prep is exactly the same (don't skip woodpecker step). Additional step is that I wipe the surface with wet cloth after sanding. I pre-mix a small amount of Gorilla glue with few drops of water - it will start foaming and expanding almost immediately. I use brush to spread that glue on both surfaces. Work fast because the glue will start setting up in about 5 minutes. Gorilla is more forgiving than CA because you can move parts after putting them together for easy adjustment. CA may not let you do it as it can bond solid without warning. Gorilla glue will be hard (full strength) in about 1 hour.