title: Effects of vitamin E blending on plastic deformation mechanisms of highly crosslinked ultrahigh molecular weight polyethylene (HXL-UHMWPE) in total hip arthroplasty.
abstract: The molecular mobility and crystalline texture development in highly crosslinked ultrahigh molecular weight polyethylene (HXL-UHMWPE) blended with antioxidant vitamin E (VE, dl-α-tocopherol) were studied via uniaxial compression at room temperature by means of confocal/polarized Raman spectroscopy. The results were compared to morphological analyses under the same compression conditions performed on HXL-UHMWPE prepared in exactly the same way but blending VE into the polyethylene resin (VE-free HXL-UHMWPE). These comparative analyses allow us to evaluate the physical role of VE in morphological alterations of HXL-UHMWPE induced by compression deformation, which can greatly affect its micromechanical behavior. Molecular rearrangement and phase transitions in crystalline and non-crystalline phase, i.e. amorphous and intermediate (third) phase, were found to be part of a reconstruction process after plastic deformation in the samples. Although VE-blended HXL-UHMWPE exhibited more pronounced molecular mobility, as evidenced by its significant deformation-induced texturing, crystallinity change was totally inhibited by the presence of VE during deformation. On the other hand, amorphous-to-intermediate phase transition was confirmed. VE-free HXL-UHMWPE also presented significant crystallization after deformation, but its surface texture evolution occurred to a much lesser extent. This study suggests that the addition of VE induced earlier activation of compression deformation modes in crystalline and non-crystalline phases (e.g. chain slip, interlamellar shear and rotation) due to an increase in polyethylene chain mobility.
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan; Department of Bone and Joint Biomaterial Research, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan. Electronic address: yasuhito@tokyo-med.ac.jp.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan.
authors.forename: Kengo
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pezzotti
mesh_terms: D016880:Anisotropy; D019644:Arthroplasty, Replacement, Hip; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D003460:Crystallization; D018360:Crystallography, X-Ray; D006801:Humans; D010969:Plastics / Q000737:chemistry / Q000494:pharmacology*; D011095:Polyethylenes / Q000494:pharmacology*; D013059:Spectrum Analysis, Raman; D014810:Vitamin E / Q000494:pharmacology*
chemical_list: D003432:Cross-Linking Reagents; D010969:Plastics; D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene; D014810:Vitamin E
keywords: Compression; Morphology; Polyethylene; Raman spectroscopy; Vitamin E