Section 07 PLASTICS AND ARTICLES THEREOF; RUBBER AND ARTICLES THEREOF 39 PLASTICS AND ATRICLES THEREOF 39 03 POLYMERS OF STYRENE, IN PRIMARY FORMS. 39 03 20 STYRENE-ACRYLONITRILE (SAN) COPOLYMERS. Commodity Code Description 39 03 20 00 STYRENE-ACRYLONITRILE (SAN) COPOLYMERS.