to water vapor and oxygen, helping to preserve the freshness of food. There are concerns about the transfer of plasticizers from PVC into food. Pliofilm was made of various kinds of rubber chloride. Used in the middle of the 20th century, it could be heat-sealed.

A common, cheaper alternative to PVC is low-density polyethylene (LDPE). It is less adhesive than PVC, but this can be remedied by adding linear low-density polyethylene