EPR power saturation techniques and spectral differentiation are used to isolate and simulate radical species in UHMWPE

Durant, Jason J.; Jahan, M. S.

doi:10.1016/j.nimb.2005.04.011

Cited by 39 publications

(40 citation statements)

References 12 publications

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“…[1,6] The EPR spectra parameters of species A are consistent with those of the most commonly occurring macroradicals in PE, i.e. secondary alkyl macro-radicals.…”

Section: Species a (Secondary Alkyl Macro-radical)supporting

confidence: 60%

“…Ohnishi [38] in 1961 mentioned a result similar to the one here discussed (a seven line spectrum with 1.3 mT separation) without reporting the experimental trace and without proposing an assignment. More recently, Jahan et al [6] assigned a similar spectrum to an allyl species. In the present case, however, the EPR parameters extracted from the computer simulation (Table 2) are not compatible with the hypothesis of an allyl species and are also in contrast with many other papers.…”

Section: Species C (Tertiary Alkyl Macro-radical)mentioning

confidence: 94%

“…In the literature some different hypothesis have been proposed. [3,6] According to the spin Hamiltonian parameters derived from computer simulation (Fig. 5(B) and Table 2) and to data available wileyonlinelibrary.com/journal/mrc in literature it is possible to indicate for this species the nature of an allyl macro-radical [3,32,33] CH CH CH CH 2 CH 2 radical B CH CH 2 CH CH 2 CH with the unpaired electron interacting with two α-H, two β-H and with a α -H located nearby the double bond and the radical carbon.…”

Section: Species B (Allyl Macro-radical)mentioning

confidence: 99%

“…The power saturation technique (use of high microwave power) can be adopted to differentiate the signals of overlapping radicals having similar g values and hyperfine coupling constants on the basis of their saturation behaviour. Jahan et al [6] first reported EPR spectra of irradiated PE obtained at high microwave power but the interpretation of their spectra is not convincing.…”

Section: Introductionmentioning

confidence: 99%

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Electron beam radiation effects on UHMWPE: an EPR study

Brunella¹,

Paganini²

2011

Magnetic Reson in Chemistry

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Electron paramagnetic resonance (EPR) technique has been employed to detect and characterise a series of different radical species generated in ultra-high molecular weight polyethylene (UHMWPE) via electron beam irradiation. Three different radical species have been found and assigned on the basis of their EPR spectra and of the related computer simulations. A secondary alkyl species, the prevalent one, is present immediately after irradiation, an allyl species appears only 24 h after irradiation when the alkyl species disappears.The third species, clearly visible at high microwave power only, has been observed for the first time and assigned to a tertiary alkyl carbon radical, whose formation is strictly connected with a Y-shape crosslink and a migration of the unpaired electron on a carbon atom localised in an adjacent position.

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“…[1,6] The EPR spectra parameters of species A are consistent with those of the most commonly occurring macroradicals in PE, i.e. secondary alkyl macro-radicals.…”

Section: Species a (Secondary Alkyl Macro-radical)supporting

confidence: 60%

Section: Species C (Tertiary Alkyl Macro-radical)mentioning

confidence: 94%

Section: Species B (Allyl Macro-radical)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electron beam radiation effects on UHMWPE: an EPR study

Brunella¹,

Paganini²

2011

Magnetic Reson in Chemistry

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“…2(a) and (b) clearly demonstrate that the intensity of R2 increases with microwave power and that of R1 increases as microwave power increases to 4 mW and then decreases. Power saturation behaviour of R2 is consistent with that of an oxygen-centred radical [10], and of R1 is similar to that of a carboncentred radical. The resonance spectrum of R2 with minimum interference from R1 was used to calculate gvalue of radical R2.…”

Section: Isolation Of Radicals Using Power Saturation Methodssupporting

confidence: 66%

Examination of the long-lived, oxygen-induced radicals in irradiated ultra-high molecular weight polyethylene

Shah

Fuzail

2007

Nuclear Instruments and Methods in Physics Research Section B:

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Kinetic and thermomechanical analysis of hydrophobic–hydrophilic copolymer thermosets synthesized via free‐radical polymerization

Rahmathullah

Elabd

Palmese

2009

J of Applied Polymer Sci

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The synthesis of a crosslinked copolymer of hydrophobic and hydrophilic monomers, diglycidyl ether of bisphenol A vinyl ester (VE), and 2-acrylamido 2-methyl 1-propane sulfonic acid (AMPS) respectively, is discussed. A methodology for real-time monitoring of the copolymerization reaction using transmission mode near infrared (NIR) spectroscopy was employed that resolves overlapping peaks associated with the reactive double bonds. The influence of solvent, monomer ratio, and initiator concentration on the kinetic behavior of the system was investigated. The method of Mayo and Lewis was used to provide a qualitative understanding of the microstructure being formed. At low conversions (<15%) and within the compositions of interest, greater VE homopolymerization as compared with AMPS homopolymerization was observed and the product of the reactivity ratios (r AMPS .r VE ) was close to 0.5, suggesting the formation of a moderately random copolymer structure. Thermo-mechanical analysis shows large concentrations of AMPS had a plasticizing effect on the network structure. Solvent removal using supercritical carbon dioxide and thermal drying were compared, and the drying technique were shown to have an effect on the glass transition temperature (T g ), with the lowest T g being 146 C for supercritically dried samples and 121 C for thermally dried systems. Gel permeation chromatography shows that there is a significant fraction of an unbound mobile phase within the network structure that might be acting as a plasticizing agent for the copolymer structure.

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EPR power saturation techniques and spectral differentiation are used to isolate and simulate radical species in UHMWPE

Cited by 39 publications

References 12 publications

Electron beam radiation effects on UHMWPE: an EPR study

Electron beam radiation effects on UHMWPE: an EPR study

Examination of the long-lived, oxygen-induced radicals in irradiated ultra-high molecular weight polyethylene

Kinetic and thermomechanical analysis of hydrophobic–hydrophilic copolymer thermosets synthesized via free‐radical polymerization

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