In the never-ending search for new materials, I came across the Plastic Fantastic Library. I have only explored it a bit, but it has articles on new materials, including more sustainable attempts at plastics, and has a search feature where you can enter in characteristics from a pretty varied assortment, and it will suggest materials.
They have also put together sample boxes, of 5 different categories of plastics. The checkout is not great, but I think I ordered a box of bio-plastics and recycled polymers to check out… I’ll report back if it arrives.
UPDATE: The sample boxes cost 65.18EUR and you need to pay via Paypal. Not interested. There are already numerous services out there (like Material Connexion) but it is still nice to have options.