Dielectric and dynamic mechanical relaxation studies on poly(aryl ether ketone)s

Goodwin, Andy A; Hay, J. N.

doi:10.1002/(sici)1099-0488(19980415)36:5<851::aid-polb12>3.0.co;2-8

Cited by 19 publications

(24 citation statements)

References 6 publications

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“…Accordingly, the interaction time increases for any given relaxation volume within the interaction volume under the sliding tip [11]. For the above calculated values for contact radii at a sliding speed of 500 nm=s, we find that the interaction time varies from 34 to 44 ms. With activation energies for of E a ¼ 11 eV and of E a ¼ 0:4-0:7 eV (typical for various PAEKs [13][14][15][16]), we obtain temperature shifts of 1 order of magnitude below the observed effect. Even if we consider the (aforementioned) length scale of cooperativity for the time scale estimation [22], we do not obtain the measured shift.…”

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confidence: 82%

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Nanoscale Frictional Dissipation into Shear-Stressed Polymer Relaxations

et al. 2009

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Sliding friction between a silicon tip and a highly cross-linked polyaryletherketone film is studied using friction force microscopy. The friction force as a function of temperature between 150 and 500 K shows distinctive maxima corresponding to alpha and beta polymer relaxations in dynamic mechanical analysis (DMA). In contrast to DMA, the nanoscale friction shows comparable coupling of mechanical energy to both relaxation modes. We report a strong shift in the peak temperatures with applied load. This effect is modeled with an Arrhenius activation by incorporating the applied shear stress in the effective activation energy of the two relaxations. The effect of the stress-shifted relaxation on friction-versus-load experiments is discussed.

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confidence: 82%

“…The broad peak is caused by several individual relaxations. A transition at around 150 K has been previously observed for a closely related polymer, polyetheretherketone (PEEK) [13][14][15][16]. It has been shown that this relaxation is linked to a rotation of aromatic rings around the C-C bonds in the polymer backbone.…”

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confidence: 89%

Nanoscale Frictional Dissipation into Shear-Stressed Polymer Relaxations

et al. 2009

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“…The α relaxation is attributed to concerted rotational mobility of chain segments involving possibly 15 to 25 repeating units and appears as a sharp peak at 150°C. The second α relaxation is due to the relaxation of the newly formed crystal portion during the heating scan and appears as a shoulder at 165°C . The ionic conductivity was characterized by a large increase in the dielectric loss, ε ″, with increasing temperature.…”

Section: Resultsmentioning

confidence: 99%

Molecular dynamics in ion‐irradiated poly(ether ether ketone) investigated by two‐dimensional correlation dielectric relaxation spectroscopy

Lafi

2013

Polymers for Advanced Techs

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This paper reports the first use of temperature–temperature 2D correlation dielectric relaxation spectroscopy (2D COS‐DRS) to study the molecular relaxation dynamics in ion‐irradiated poly(ether ether ketone) (PEEK). With the help of the high resolution and high sensitivity of 2D COS‐DRS, it was possible to locate the position of the motion of water molecules in the dielectric spectrum of PEEK. This occurred at −20°C and increased in intensity on increasing water contents. On irradiation, a new relaxation was observed at −75°C and −85°C for proton and helium ion‐irradiated samples, respectively. This increased in intensity on increasing radiation dose and was assigned to main‐chain phenyl motions of the cross‐linked units of the polymer. 2D COS‐DRS was also successfully applied to resolve the overlap in molecular events in the region of glass transition. Three processes that change in different directions with respect to ion irradiation dose were identified. These were at 160°C, 175°C, and 240°C and were assigned to the α relaxation, second α relaxation, and the onset of conductivity, respectively. In addition, hybrid 2D COS‐DRS was used to investigate the effect of the so‐called linear energy transfer effect, and the results showed that helium ions were more effective in cross‐linking PEEK. Copyright © 2013 John Wiley & Sons, Ltd.

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“…The testing procedure is carried out to verify if the renewable Pebax-b has properties comparable to those of the traditional Pebax-a currently adopted in the injection of the bellow. The testing procedures is based on a combination of tensile and bending mechanical tests, Dynamic Mechanical Analysis (DMA) (Ghosh et al 1998, Sheth et al 2003, Broadband Dielectric Spectroscopy (BDS) (Goodwin and Hay 1998, Kalakkunnath et al 2007, Viciosa et al 2007) and Thermogravimetric Analysis (TGA) (Boulares et al 2000, Wang et al 2007, Luyt et al 2010. All these tests are made both on not-degraded and degraded materials to estimate the possible response in the different conditions.…”

Section: Investigation Of Materials Propertiesmentioning

confidence: 99%

“…At lower frequencies the influence of the conductivity loss is emphasized. This contribution should be subtracted when analysing isothermal data for the investigation of -transition peak as well known from the Goodwin and Hay (1998) report.…”

Section: Experimental Testingmentioning

confidence: 99%

Investigation of the mechanical performances of material and structural configuration of telemark ski boots

Parisotto¹,

Marcolin²,

Marcolin³

et al. 2012

Footwear Science

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A design procedure for telemark ski boots is presented, characterized by an integrated approach by means of experimental and numerical analyses. Material properties are investigated adopting different experimental tests addressed to the characterization of the behaviour of the ski boot polymeric materials, with particular regard to elastic, viscous, temperature-dependent and degradation characteristics. Material constitutive models are provided taking into account the experimental achievement. Ski boots morphology is defined adopting solid model technique and is subsequently transposed in numerical models that allow the mechanical response of the boot structure to be defined. Specific boundary conditions are assumed to mimic the binding effects. The investigation allows for an accurate interpretation of global and local effects induced in the specific boot as a function of loading considered. The present procedure can provide a valid set of information of the mechanical response of the boot in direct relation with the real use, taking into account loading and the environmental conditions, and leading to the possibility of defining the reliability and durability properties of the product. The present work is mostly addressed to offer a preliminary report with regard to the procedure adopted for the characterization of the materials and the constitutive formulation to be assumed for the numerical model aimed at the accurate design of a specific region of the ski boot.

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Dielectric and dynamic mechanical relaxation studies on poly(aryl ether ketone)s

Cited by 19 publications

References 6 publications

Nanoscale Frictional Dissipation into Shear-Stressed Polymer Relaxations

Nanoscale Frictional Dissipation into Shear-Stressed Polymer Relaxations

Molecular dynamics in ion‐irradiated poly(ether ether ketone) investigated by two‐dimensional correlation dielectric relaxation spectroscopy

Investigation of the mechanical performances of material and structural configuration of telemark ski boots

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