Polyester is a category of polymers, or, more specifically condensation polymers, which contain the ester functional group in their main chain. Polyester is combustible but due to its thermoplastic nature, it tends to shrink away from the flame source and often self-extinguishes. 

Polyurethane products have many uses. Over three quarters of the global consumption of polyurethane products is in the form of foams, with flexible and rigid types being roughly equal in market size. In both cases, the foam is usually behind other materials. 

Polyethylene, or PE, is perfect for wrapping delicate items because it is soft, non-abrasive and lightweight. For that reason it is commonly used whenever cushioning material is needed. It's available in a variety of thicknesses to best suit your needs and, because it is CFC free, this packaging material is kind to the environment. 

Cross Link Polyethylene, or PEX, is a medium- to high-density polyethylene containing cross-link bonds introduced into the polymer structure, changing the thermoplast into an elastomer.