U.S. Patent 8,680,173 (March 25, 2014), "Sequentially Cross-Linked Polyethylene," Aiguo Wang, John H. Dumbleton, Aaron Essner, and Shi-Shen Yau (Howmedica Osteonics Corporation, Mahwah, Newjersey, USA).
Radiation-induced crosslinking improves the properties of ultra-high molecular-weight polyethylene (UHMWPE) prostheses. However, after this process, some free radicals persist, reacting with oxygen and other reactive chemicals, degrading properties such as wear and oxidation resistance.
Wang et al. produced an improved polyethylene, especially UHMWPE materials, by a sequence of irradiation steps with low doses and annealing, resulting in minimal free-radical residue. The process may be applied either to a preformed material, such as a rod, bar, or sheet, or to a finished part. This process does not use stabilizers, antioxidants, or any other chemical which may have adverse effects in their orthopedic applications. For each stage, doses range from 5 to 10 Mrads, with 110-135[degrees]C annealing for four hours.
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|Title Annotation:||INDUSTRY PATENTS|
|Article Type:||Brief article|
|Date:||Jul 1, 2014|
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