Dielectric study of post-irradiation effects in gamma-irradiated polyethylenes

Suljovrujić, E.

doi:10.1016/j.radphyschem.2010.02.008

Cited by 21 publications

(7 citation statements)

References 47 publications

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“…At this temperature, the chain displacement is several nm per second and can occur between amorphous and crystalline regions. Such a picture is in good relationship with the transition temperature range at SANS measurements and the dynamic of α-relaxation of the neat HDPE sample from temperature-dependent dielectric measurements [69,70]. These transformations in the nanoscale level give a new insight into the changes in mechanical properties (e.g., tensile strength [71]) observed in some quenched composites after mild annealing.…”

Section: Thermal Stability Of the Polymer Nanocomposite Structuresupporting

confidence: 53%

Composite Films of HDPE with SiO2 and ZrO2 Nanoparticles: The Structure and Interfacial Effects

et al. 2021

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Herein, we investigated the influence of two types of nanoparticle fillers, i.e., amorphous SiO2 and crystalline ZrO2, on the structural properties of their nanocomposites with high-density polyethylene (HDPE). The composite films were prepared by melt-blending with a filler content that varied from 1% to 20% v/v. The composites were characterized by small- and wide-angle x-ray scattering (SAXS and WAXS), small-angle neutron scattering (SANS), Raman spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). For both fillers, the nanoaggregates were evenly distributed in the polymer matrix and their initial state in the powders determined their surface roughness and fractal character. In the case of the nano-ZrO2 filler, the lamellar thickness and crystallinity degree remain unchanged over a broad range of filler concentrations. SANS and SEM investigation showed poor interfacial adhesion and the presence of voids in the interfacial region. Temperature-programmed SANS investigations showed that at elevated temperatures, these voids become filled due to the flipping motions of polymer chains. The effect was accompanied by a partial aggregation of the filler. For nano-SiO2 filler, the lamellar thickness and the degree of crystallinity increased with increasing the filler loading. SAXS measurements show that the ordering of the lamellae is disrupted even at a filler content of only a few percent. SEM images confirmed good interfacial adhesion and integrity of the SiO2/HDPE composite. This markedly different impact of both fillers on the composite structure is discussed in terms of nanoparticle surface properties and their affinity to the HDPE matrix.

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Section: Thermal Stability Of the Polymer Nanocomposite Structuresupporting

confidence: 53%

Composite Films of HDPE with SiO2 and ZrO2 Nanoparticles: The Structure and Interfacial Effects

et al. 2021

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“…Different molecular mechanisms have been proposed to contribute to the β relaxation in specific polyethylenes, in addition to those related to the glass transition 24. In general, the beta relaxation is accepted to stem from the relaxation of chain units in the interfacial region via fold‐surface, chain‐end, branch‐point molecular motions, and chain rotation 25. Therefore, the higher interlamellar content (i.e., lower crystallinity), the stronger the beta relaxation as demonstrated for chlorinated and short‐chain branched polyethylenes 25–27.…”

Section: Resultsmentioning

confidence: 99%

“…In general, the beta relaxation is accepted to stem from the relaxation of chain units in the interfacial region via fold‐surface, chain‐end, branch‐point molecular motions, and chain rotation 25. Therefore, the higher interlamellar content (i.e., lower crystallinity), the stronger the beta relaxation as demonstrated for chlorinated and short‐chain branched polyethylenes 25–27. Moreover, the beta relaxation is absent in linear high‐density polyethylenes (HDPEs) in agreement with their much lower interlamellar content.…”

Section: Resultsmentioning

confidence: 99%

Thermal and dynamic mechanical properties of vitamin E infused and blended ultra‐high molecular weight polyethylenes

Puértolas

Martínez-Morlanes

Mariscal

et al. 2010

J of Applied Polymer Sci

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Vitamin E (or a-tocopherol) is an alternative via to thermal treatments to achieve oxidative stability of gamma or electron beam irradiated ultra-high molecular weight polyethylenes (UHMWPE) used in total joint replacements. Our aim was to study the effects of vitamin E on the molecular dynamics and microstructural properties of UHMWPE. We hypothesized that the antioxidant would plasticize UHMWPE. Vitamin E was incorporated into UHMWPE at different concentrations by diffusion and blending and detected by ultraviolet and infrared spectroscopies from 500 ppm and 4000 ppm, respectively. Dynamic mechanical thermal analysis was used to characterize the influence of this antioxidant in the relaxations of the raw material. Differential scanning calorimetry and transmission electron microscopy served to characterize thermal and microstructure properties, respectively. Vitamin E concentrations above 3% by weight significantly reduced the degree of crystallinity and increased the melting transition temperature of raw UHMWPE. The presence of increasing concentrations of a-tocopherol introduced and/or strengthened the beta relaxation, which was also shifted toward gradually lower temperatures and had rising activation energies up to 188 kJ/mol. In addition, the gamma relaxation remained unaltered on vitamin E addition. Therefore, no plasticizing effects of vitamin E on the molecular dynamics of UHMWPE could be confirmed from mechanical spectroscopy data. However, the a relaxation was modified in intensity and location due to the changes in the degree of crystallinity introduced by the incorporation of vitamin E.

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“…This relaxation is widely accepted to be related to the relaxation of chain units in the interfacial zone between the lamella and its surrounding amorphous region . Mechanisms associated to chain‐end, fold‐surface, branch‐point molecular motions, and chain rotation are involved in this relaxation . Therefore, higher crystalline content and the prevalent structural linearity of Nitta and Tanaka may result in the absence of this relaxation.…”

Section: Resultsmentioning

confidence: 99%

“…These units are introduced during the synthesis of the powder or during the consolidation process at high temperature and pressure. High density, low density, or linear low density polyethylenes have been extensively studied in order to know the influence that different processes like crystallization, aging, irradiation, or the presence of antioxidants, blends, reinforcements or nanoreinforcements produce to the aforementioned relaxations . In contrast to these studies related to polyethylenes, few works appeared in the literature concerning the dielectric behavior of ultra high molecular weight polyethylene (UHMWPE), which presents a low dielectric constant and dielectric loss tangent.…”

Section: Introductionmentioning

confidence: 99%

Dielectric behavior induced by vitamin E and electron beam irradiation in ultra high molecular weight polyethylene

Puértolas

Martínez-Morlanes

Teruel

et al. 2014

J of Applied Polymer Sci

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Radiation cross‐linked ultra high molecular weight polyethylenes (UHMWPEs) have been successfully used as wear resistant bearing surfaces in total joint arthroplasty. A recent development in this field is the incorporation of the antioxidant vitamin E into radiation cross‐linked UHMWPE. This study investigates the effects of radiation cross‐linking and vitamin E incorporation on the dielectric behavior of UHMWPE. The dielectric relaxations of virgin and 0.1 wt % vitamin E‐blended UHMWPE and their irradiated counterparts (up to 300 kGy dose) were investigated. To determine the effect of vitamin E content alone, vitamin E‐loaded UHMWPEs were used. The results showed that radiation cross‐linking and vitamin E content both increased dielectric polarization in UHMWPE and under some conditions induced electrical conductivity. This result is significant because it shows that the conductive response of UHMWPE‐bearing surfaces may depend on manufacturing processes and additives. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40844.

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Dielectric study of post-irradiation effects in gamma-irradiated polyethylenes

Cited by 21 publications

References 47 publications

Composite Films of HDPE with SiO2 and ZrO2 Nanoparticles: The Structure and Interfacial Effects

Composite Films of HDPE with SiO2 and ZrO2 Nanoparticles: The Structure and Interfacial Effects

Thermal and dynamic mechanical properties of vitamin E infused and blended ultra‐high molecular weight polyethylenes

Dielectric behavior induced by vitamin E and electron beam irradiation in ultra high molecular weight polyethylene

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