Analysis of Hydroperoxides in Solid Polyethylene by MAS <sup>13</sup>C NMR and EPR

Assink, Roger A.; Celina, Mathias C.; Dunbar, Timothy D.; Alam, Todd M.; Clough, R.L.; Gillen, K.T.

doi:10.1021/ma991970d

Cited by 46 publications

(31 citation statements)

References 33 publications

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“…This resonance is identified with hydroperoxides and/or dialkyl peroxides (peak a in Figure 1). In their solid-state 13 C NMR analysis of γ-irradiated, 13 C enriched polyethylene films, Assink et al 10 found a similar resonance at ∼85 ppm which they attributed to secondary hydroperoxides. (c) methyl ketones; (d) esters and/or peresters; (e) carboxylic acids and/or esters; (f) in-chain ketones; (g) ketals and/or acetals.…”

Section: Resultsmentioning

confidence: 99%

Solid-State ¹³C NMR Investigation of the Oxidative Degradation of Selectively Labeled Polypropylene by Thermal Aging and γ-Irradiation

et al. 2005

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Unstabilized polypropylene (PP) films having selective 13 C isotopic labeling were subjected to thermal aging at 50, 80, and 109°C and to γ-irradiation at 24 and 80°C. The oxidized films were examined using solid-state 13 C nuclear magnetic resonance (NMR) spectroscopy. Dramatic differences were found in the type and distribution of oxidation products originating from the three carbon atom sites within the PP macromolecule (tertiary carbon, secondary carbon, and methyl side group). Most of the oxidation products that formed on the polymer chain originated through chemical reactions at the PP tertiary carbons. Under all of the aging conditions examined, tertiary peroxides (from the PP tertiary site) were the most abundant functional group produced. Also originating from the PP tertiary carbon were significant amounts of tertiary alcohols, together with several more minor products that included "chain-end" methyl ketones. No significant amount of peroxides or alcohols associated with the PP secondary carbon sites was detected. A substantial yield of carboxylate groups was identified (acids, esters, etc.). The majority of these originated from the PP secondary carbon site, from which other minor products also formed, including in-chain ketones. We found no measurable yield of oxidation products originating from reaction at the PP methyl group. Remarkably similar distributions of the major oxidation products were obtained for thermal aging at different temperatures, whereas the product distributions obtained for irradiation at the different temperatures exhibited significant differences. Time-dependent concentration plots have been obtained, which show the amounts of the various oxidation products originating at the different PP sites, as a function of the extent of material oxidation.

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Section: Resultsmentioning

confidence: 99%

Solid-State ¹³C NMR Investigation of the Oxidative Degradation of Selectively Labeled Polypropylene by Thermal Aging and γ-Irradiation

et al. 2005

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“…We reviewed the vitamin E-stabilized UHMWPE development with the following questions in mind: (1) What is the rationale behind protecting irradiated UHMWPE against oxidation by vitamin E? (2) What are the effects of vitamin E on the microstructure, tribologic, and mechanical properties of irradiated UHMWPE? (3) Is vitamin E expected to affect the periprosthetic tissue negatively?…”

Section: Discussionmentioning

confidence: 99%

“…(2) What are the effects of vitamin E on the microstructure, tribologic, and mechanical properties of irradiated UHMWPE? (3) Is vitamin E expected to affect the periprosthetic tissue negatively?…”

Section: Introductionmentioning

confidence: 99%

Vitamin E-stabilized UHMWPE for Total Joint Implants: A Review

Bracco

Oral

2011

Clinical Orthopaedics &Amp; Related Research

255

162

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Background Osteolysis due to wear of UHMWPE limits the longevity of joint arthroplasty. Oxidative degradation of UHMWPE gamma-sterilized in air increases its wear while decreasing mechanical strength. Vitamin E stabilization of UHMWPE was proposed to improve oxidation resistance while maintaining wear resistance and fatigue strength. Questions/purposes We reviewed the preclinical research on the development and testing of vitamin E-stabilized UHMWPE with the following questions in mind: (1) What is the rationale behind protecting irradiated UHMWPE against oxidation by vitamin E? (2) What are the effects of vitamin E on the microstructure, tribologic, and mechanical properties of irradiated UHMWPE? (3) Is vitamin E expected to affect the periprosthetic tissue negatively? Methods We performed searches in PubMed, Scopus, and Science Citation Index to review the development of vitamin E-stabilized UHMWPEs and their feasibility as clinical implants.Results The rationale for using vitamin E in UHMWPE was twofold: improving oxidation resistance of irradiated UHMWPEs and fatigue strength of irradiated UHMWPEs with an alternative to postirradiation melting. Vitamin E-stabilized UHMWPE showed oxidation resistance superior to that of irradiated UHMWPEs with detectable residual free radicals. It showed equivalent wear and improved mechanical strength compared to irradiated and melted UHMWPE. The biocompatibility was confirmed by simulating elution, if any, of the antioxidant from implants.Conclusions Vitamin E-stabilized UHMWPE offers a joint arthroplasty technology with good mechanical, wear, and oxidation properties. Clinical Relevance Vitamin E-stabilized, irradiated UHMWPEs were recently introduced clinically. The rationale behind using vitamin E and in vitro tests comparing its performance to older materials are of great interest for improving longevity of joint arthroplasties.

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“…These peroxy radicals, in the absence of an antioxidant such as vitamin E, abstract a hydrogen atom from other polyethylene chains, creating new primary free radicals, which can then react with oxygen to further this chain of reactions [1,60]. When peroxy free radicals react with hydrogen, they form hydroperoxides, which are not stable and degrade into oxidation products, mainly ketones, esters, and acids [2,3,16,17]. The formation of these oxidation products is accompanied by chain scission and a decrease in the molecular weight of polyethylene, reducing its mechanical properties [14,37].…”

Section: Introductionmentioning

confidence: 99%

Vitamin E diffused, highly crosslinked UHMWPE: a review

Oral

Muratoglu

2010

International Orthopaedics (SICOT)

217

133

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Highly crosslinked UHMWPE has become the bearing surface of choice in total hip arthroplasty. First generation crosslinked UHMWPEs, clinically introduced in the 1990s, show significant improvements compared to gamma sterilised, conventional UHMWPE in decreasing wear and osteolysis. These crosslinked UHMWPEs were thermally treated (annealed or melted) after irradiation to improve their oxidation resistance. While annealing resulted in the retention of some oxidation potential, postirradiation melted UHMWPEs had reduced fatigue strength due to the crystallinity loss during melting. Thus, the stabilisation of radiation crosslinked UHMWPEs by the diffusion of the antioxidant vitamin E was developed to obtain oxidation resistance with improved fatigue strength by avoiding post-irradiation melting. A two-step process was developed to incorporate vitamin E into irradiated UHMWPE by diffusion to obtain a uniform concentration profile. Against accelerated and real-time aging in vitro, this material showed superior oxidation resistance to UHMWPEs with residual free radicals. The fatigue strength was improved compared to irradiated and melted UHMWPEs crosslinked using the same irradiation dose. Several adverse testing schemes simulating impingement showed satisfactory behaviour. Peri-prosthetic tissue reaction to vitamin E was evaluated in rabbits and any effects of vitamin E on device fixation were evaluated in a canine model, both of which showed no detrimental effects of the inclusion of vitamin E in crosslinked UHMWPE. Irradiated, vitamin E-diffused, and gamma sterilised UHMWPEs have been in clinical use in hips since 2007 and in knees since 2008. The clinical outcome of this material will be apparent from the results of prospective, randomised clinical studies. IntroductionOsteolysis triggered mainly by ultrahigh molecular weight polyethylene (UHMWPE) wear particles has been one of the major problems in total hip arthroplasty along with instability/dislocation and infection [7]. Highly crosslinked UHMWPEs were developed using high-dose irradiation (50-100 kGy) to decrease the wear rate of UHMWPE [44,46] and have become the standard-of-care after their first decade of service, especially in North America [61].Irradiation causes crosslinking in the amorphous phase of the UHMWPE [33], but also initiates the formation of free radicals in the crystalline phase [23], unable to recombine due to structural limitations, they become trapped for long periods of time [29]. These residual free radicals are believed to migrate to the crystalline/amorphous interface and cause oxidative degradation in the material [16][17][18]59, 69] through a cascade of reactions with oxygen [32,71].In first generation crosslinked UHMWPEs [34], postirradiation thermal treatment was used to increase the oxidation resistance (Fig. 1). One approach was to annealThe studies discussed here were performed by research funding in part from NIH/NIAMS

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Analysis of Hydroperoxides in Solid Polyethylene by MAS ¹³C NMR and EPR

Abstract: Abstract'3C-enriched polyethylene was subjected to y-irradiation in the presence of air at

Cited by 46 publications

References 33 publications

Solid-State ¹³C NMR Investigation of the Oxidative Degradation of Selectively Labeled Polypropylene by Thermal Aging and γ-Irradiation

Solid-State ¹³C NMR Investigation of the Oxidative Degradation of Selectively Labeled Polypropylene by Thermal Aging and γ-Irradiation

Vitamin E-stabilized UHMWPE for Total Joint Implants: A Review

Vitamin E diffused, highly crosslinked UHMWPE: a review

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Analysis of Hydroperoxides in Solid Polyethylene by MAS 13C NMR and EPR

Abstract: Abstract'3C-enriched polyethylene was subjected to y-irradiation in the presence of air at

Cited by 46 publications

References 33 publications

Solid-State 13C NMR Investigation of the Oxidative Degradation of Selectively Labeled Polypropylene by Thermal Aging and γ-Irradiation

Solid-State 13C NMR Investigation of the Oxidative Degradation of Selectively Labeled Polypropylene by Thermal Aging and γ-Irradiation

Vitamin E-stabilized UHMWPE for Total Joint Implants: A Review

Vitamin E diffused, highly crosslinked UHMWPE: a review

Contact Info

Product

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Analysis of Hydroperoxides in Solid Polyethylene by MAS ¹³C NMR and EPR

Solid-State ¹³C NMR Investigation of the Oxidative Degradation of Selectively Labeled Polypropylene by Thermal Aging and γ-Irradiation

Solid-State ¹³C NMR Investigation of the Oxidative Degradation of Selectively Labeled Polypropylene by Thermal Aging and γ-Irradiation