Understanding Van de Graaff Generator Behavior: Paper vs. Aluminum Contact

[Soaring Crane]

I don't quite understand the behavior of a couple of objects when they are placed in close contact with a VDG generator. When a piece of paper is positioned near the generator, why is it immediately "plastered" to the sphere's side while a piece of aluminum is drawn to the side but then repels away from the generator?

Thanks for any replies.

 

[Schumanx]

I think this is due largely to the nature of the materials. Let's start with the aluminum We can start off and just assume that it is at nuetral then it touches the charged outer side of the generator which has a charge, which is why it was attracted to it. The aluminum is now charged however it has the same charge as the surface it is next to now they repel as they are opposite charges. The paper however is not quite so conductive and my guess would be that the close proximity of the charge polarized a few of the molecules in the paper so that it stayed there. Or that, once the paper got close to the charged generator instead of gaining a charge a few of the molecules in the paper that were sumwhat free to move shifted around so that they were alligned with the charge coming from the generator.

sorry for the spelling