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Title: Grafting of α-tocopherol upon γ-irradiation in UHMWPE probed by model hydrocarbons
Authors : Badertscher, Remo
Lerf, Reto
Delfosse, Daniel
Adlhart, Christian
Published in : Polymer Degradation and Stability
Volume(Issue) : 97
Issue : 11
Pages : 2255
Pages to: 2261
Publisher / Ed. Institution : Elsevier
Publisher / Ed. Institution: Amsterdam
Issue Date: Nov-2012
License (according to publishing contract) : Licence according to publishing contract
Type of review: Peer review (Publication)
Language : English
Subjects : Gamma irradiation; Antioxidant; Mechanism; Vitamin E
Subject (DDC) : 540: Chemistry
620: Engineering
Abstract: Today, UHMWPE implants are stabilized with α-tocopherol and cross-linked by irradiation in order to reduce wear. Little is known about the structural transformation of the antioxidant α-tocopherol upon irradiation. In the present investigation, the major irradiation reaction products of α-tocopherol dissolved at 0.1 wt. % in liquid model hydrocarbons were characterized spectroscopically and by independent synthesis. We observed only a single product group, namely phenolic alkyl ethers formed by radical recombination of a phenoxyl radical with a secondary alkyl radical. The irradiation dose is the parameter which controls the amount of consumption of α-tocopherol. At a dose of 27.5 kGy, 31-34 % of α-tocopherol was transformed into the corresponding ether, while at 97.9 kGy, the degree of transformation was 68-76 %. The observed ether formation in the liquid model hydrocarbons explains two significant observations for the α-tocopherol stabilized polymers, namely depletion of the α-tocopherol’s phenol group upon irradiation and “grafting”, i.e. formation of a chemical bond between the polymer and its antioxidant.  
Departement: Life Sciences and Facility Management
Organisational Unit: Institute of Chemistry and Biotechnology (ICBT)
Publication type: Article in scientific Journal
DOI : 10.1016/j.polymdegradstab.2012.07.040
ISSN: 0141-3910
Appears in Collections:Publikationen Life Sciences und Facility Management

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