Using Yahoo, I searched for
Pellon Fusible for polyester fabric
My thought is that Polyester and Silk are both low heat fabrics, so both will probably use the same type of fusibles.
The Joann link has a pdf that is really good for explaining which fusibles or interfaces work with different fabrics. I couldn't figure out how to make a link to the site, so I kept a copy for myself. Try this in your browser. P012982PellonInterfacingGuide.pdf