Polyvinyl resins are family of resins based upon the vinyl monomer. The Polyvinyl class has one main sub-class: Polyvinyl Chloride (PVC) which can be rigid (PVC-R) or flexible (PVC-F). PVC can be opaque or clear. It is inherently flame retardant. Both PVC-R and PVC-F are included in this inventory. Polyvinyl Acetate (PVA or PVAc) is a second sub-class which is wood glue or white glue and not a moldable compound [This is not in our inventory]. The polyvinyl monomer is the underpinning of many plastics including polyethylene, polypropylene, and styrene, which are classified separately here. Wikipedia Link