Code of Federal Regulations Title 21. Food and Drugs § 21.177.2440 Polyethersulfone resins

(1) Poly(oxy-p-phenylenesulfonyl-p-phenylene) resins (CAS Reg. No. 25667–42–9), which have a minimum number average molecular weight of 16,000.

(2) 1,1′–sulfonylbis[4–chlorobenzene] polymer with 4,4′–(1–methylethylidene)bis[phenol] (maximum 8 percent) and 4,4′–sulfonylbis[phenol] (minimum 92 percent) (CAS Reg. No. 88285–91–0), which have a minimum number average molecular weight of 26,000.

(3) In paragraphs (a)(1) and (a)(2) of this section, the minimum number average molecular weight is determined by reduced viscosity in dimethyl formamide in accordance with ASTM method D2857–70 (Reapproved 1977), “Standard Test Method for Dilute Solution Viscosity of Polymers,” which is incorporated by reference. Copies may be obtained from the American Society for Testing Materials, 100 Barr Harbor Dr., West Conshohocken, Philadelphia, PA 19428-2959, or may be examined at the Office of Food Additive Safety (HFS–200), Center for Food Safety and Applied Nutrition, Food and Drug Administration, 5001 Campus Dr., College Park, MD 20740, 240–402–1200 or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202–741–6030, or go to:  http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.