NIST issues reference material 8457 to aid orthopedic implant manufactures and researchers.

Reference material (RM) 8457, which consists of 0.5 cm cubes of orthopedic-grade ultra-high molecular weight polyethylene that are well suited for measurements of cross-link density by a new ASTM International swell-test method, has been issued. Scientists at NIST produced the RM in response to recent interest among manufacturers and researchers of orthopedic implants to improve wear performance by ionizing radiation treatments. These treatments are known to produce new chemical bonds (cross-linking) between the polymer molecules. The extent to which cross-linking occurs during the radiation treatment is an important design variable. In recognition of its importance, ASTM International issued a new standard test method for cross-linking, F2214-02: Standard Test Method for In Situ Determination of Network Parameters of Crosslinked Ultra-High Molecular-Weight Polyethylene. The standard test method references RM 8457, along with results of a round-robin analysis of the method. NIST supplied specimens for the round-robin testing that were manufactured from the same material--RM 8456--as RM 8457.

The RM can be purchased at the Standard Reference Material/RM Web site: www.nist.gov/srm. CONTACT: Bruno Fanconi, [phone]; [e-mail] or John Tesk, [phone]; [e-mail].