Actually, I should have realised it from 5 years ago when trying to use some bits of it for windows on my 16mm locomotive. Perhaps the answer would be to drill some small hole in the hope that the Araldite will ooze through and so provide a locking mechanism, instead of an adhesive mechanism, when it sets.
You can get primers or promoters designed to make bonding to polyolefins (polythene, polypropylene) and other hard-to-stick-to plastics like silicones more effective, but they tend to be expensive. It will say something like "activator for low surface energy plastics" on the bottle.
It is a good idea to wear rubber gloves when using, some of them are a bit nasty.
There are also a few glues made for that sort of stuff, like Loctite polyolefin bonder. Again, the good ones are expensive, and they tend to be the sort of stuff with a six month shelf life.
I'm not up-to-date with the latest products, but regarding the cheaper ones, the ones which come on a card don't seem to work as well as the ones which come in separate bottles. YMMV here.
There are hot-melt glue sticks made specially for the low surface energy plastics as well.
A cheaper way is to wipe with alcohol of some sort then flame treat - pass the end of a butane or propane flame over the surface, moving quite fast, back and forward overlapping strokes.
There should be no obvious change in the plastic, if there is you did it too hot.
Glue within a few minutes of flame treating, the effect doesn't last long. You will probably need a few tries to get it right - the idea is for the glue to wet the surface thoroughly and easily.
For RTV silicone, I had good results from using one of the proprietary silicone rubber remover products to treat the surface of the cured rubber for a few minutes, before wiping it off again. The paint has survived with no problems on the silicone 'putty' of the window frames for three years now.
The reason for using RTV silicone on windows was because I was retrofitting Crittal steel window frames with sealed unit double glazed panels.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.