UHMWPE, additives Antioxidants

Medical-quality UHMWPE differs from the industrial polymer mainly in the smaller proportion of additives and trace elements. This is achieved by additional purification procedures and omission of antioxidants or stabilizers. This polymer is therefore susceptible to aging [29]. The ceramic discs used for... 

Despite the promising results presented by other antioxidants, the main oxidation stabilizers of choice are sterically hindered phenols, among which Vitamin E and Irganox (1010, 1035, 1076) stand out. These antioxidants have been shown to be more effective in radiative processes [80, 81]. Also, advances on the mechanisms of stabilization in polymer processing have shown that vitamin E is more efficient compared to other commercial additives [82,83]. Tocopherol compounds were proposed as stabilizers for polyolefins in the 1980s [84] and currently, they are the best alternative for the oxidative stabilization of highly cross-linked UHMWPEs. 

If the vitamin E movement in UHMWPE biomaterials was bom in Torino in 2003, then its conception occurred in Japan by Professor Naohide Tomita from the University of Kyoto. Japan has a history of early adoption of vitamin E both in packaging as well as in orthopedic implants. Vitamin E has been used in Japan as an environmentally friendly additive for polyolefins since the late 1980s [11]. In light of its acceptance as an effective antioxidant, a manufacturer from Japan (Nakashima Medical Co., Ltd., http //www.medical.nakashima.co.jp) was also the first supplier to produce UHMWPE blended with vitamin E for total knee replacements, and these implants have been in clinical use in Japan since 2006 [18] (Figure 16.4). The commercialization of vitamin-E-blended UHMWPE in Japan is largely based on the research efforts of Professor Tomita and Nobuyuki Shibata, who was a doctoral student at the time [1,19-21]. These studies have been recently summarized [18] consequently the contributions of the Kyoto research group are only briefly reviewed herein. 

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