The invention is directed towards a PVC resin composition comprising polyvinyl
chloride and a liquid plasticizer selected from the group consisting of: (i) a
non-linear, paraffin-soluble olefin-CO copolymer; ii) a non-linear olefin-CO copolymer
derived from non-pure feeds; iii) an olefin-CO—X terpolymer derived from
non-pure feeds; and iv) a non-linear olefin-CO—X terpolymer. A method of
preparing the resins is also described.