Relaxation processes in crystalline polymers: experimental behaviour — a review

Boyd, Richard H.

doi:10.1016/0032-3861(85)90192-2

Cited by 617 publications

(420 citation statements)

References 94 publications

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“…This view is supported by the value of the apparent activation energy of the plastic flow contribution, approx. 30 kcal/mol, which is identical to the value of the activation energy of the dielectrical e-relaxation [30]. This interpretation is in accordance with the results and conclusions of Wilding and Ward in the case of meh-spun/drawn HDPE fibers [6,7].…”

Section: Irreversible Deformation (Plastic Flow)supporting

confidence: 88%

“…Diffusion of these small defects throughout the crystal lattice results in a 180 ~ rotational-C/2 translational (screw-jump) motion of the crystalline stem [24][25][26][27][28][29]. This screw-jump mechanism is generally accepted as being the molecular origin of the dielectrical e-transition in polyethylene [24][25][26][27][28][29][30][31].…”

Section: Irreversible Deformation (Plastic Flow)mentioning

confidence: 99%

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Deformation behavior of oriented UHMW-PE fibers

Govaert

Lemstra

1992

Colloid Polym Sci

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Abstract:The mechanical behavior of gel-spun, ultra-drawn, UHMW-PE fibers was investigated as a function of temperature, stress, and time under static and dynamic loading conditions. From a phenomenological point of view, two separate contributions to the deformation behavior could be distinguished, i.e., a reversible (viscoelastic) contribution and an irreversible plastic flow component. It was investigated whether or not this distinction can be rationalized on a molecular basis. The fibers were studied using static (creep) and dynamic mechanical analysis (DMA), dilatometry, and wide-angle x-ray scattering (WAXS). The results of the combined experimental observations are discussed in an attempt to relate the deformation behavior of highly oriented PE fibers to events occurring on a molecular scale.

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Section: Irreversible Deformation (Plastic Flow)supporting

confidence: 88%

Section: Irreversible Deformation (Plastic Flow)mentioning

confidence: 99%

Deformation behavior of oriented UHMW-PE fibers

Govaert

Lemstra

1992

Colloid Polym Sci

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“…For amorphous polymers, a non-symmetric distribution of times is expected for the α relaxation, associated with macromolecular segmental motion, at temperatures immediately above the glass transition. But for semi-crystalline polymers and more generally for heterogeneous systems, published data by Boyd [55], Laredo [56], Cebe [57], Noda [58], Ryabov [59], Janik [60], Feldman [61], Ortiz-Serna [29][30] etc., show that symmetrical distributions are observed for the α relaxation processes. However, the temperature dependence of a for the β process differs from that observed for the glass rubber relaxation since it decreases with temperature.…”

Section: Dielectric Measurementsmentioning

confidence: 99%

Relaxational study of poly(vinylpyrrolidone-co-butyl acrylate) membrane by dielectric and dynamic mechanical spectroscopy

Redondo-Foj¹,

Carsí²,

Ortiz-Serna³

et al. 2013

J. Phys. D: Appl. Phys.

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A poly(vinylpyrrolidone-co-butyl acrylate) (60VP-40BA) membrane has been synthesized as a tractable and hydrophilic material, obtaining a water swelling percentage around 60%. An investigation of molecular mobility by means of Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA) and Broadband Dielectric Relaxation Spectroscopy (DRS) has been fulfilled in the dry membrane. Dielectric and viscoelastic relaxation measurements have been carried out on the 60VP-40BA sample at several frequencies between -150ºC to 150ºC .The dielectric spectrum shows several relaxation processes labelled as γ, β and α in increasing order of temperature, whereas in the mechanical spectrum only the β and α relaxation processes are completely defined. In the dielectric measurements, conductive contributions overlap the α-relaxation. The apparent activation energies have similar values for the β-relaxation in both, the mechanical and the dielectric measurements. The β process is related to the local motions of the pyrrolidone group and the γ process is connected with the butyl units motions, both located in the side chains of the polymer.

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“…It is then caused in the PVDF main chains by cooperative micro-Brownian motions within their amorphous regions [35,36]. The process at about 10 0 Hz is ascribed to the molecular motions within the crystalline fraction of the PVDF material and it is named as α C relaxation [37][38][39][40]. The presence in all the specimens of this relaxation associated with motions within crystallites confirms that the primary polymorph developed is the non-polar α-phase since it practically disappears when β crystals are majority [41].…”

Section: Electric Propertiesmentioning

confidence: 99%

Electromagnetic Shielding Features in Lightweight PVDF-Aluminum Based Nanocomposites

Arranz-Andrés¹,

Pulido-González²,

Marı́n³

et al. 2013

PIER B

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Abstract-Dependence of the electromagnetic shielding effectiveness on filler volume fraction has been investigated from attenuation upon reflection measurements over a broad frequency range in hybrids based on Poly(vinylidene fluoride)-Aluminum nanoparticles. The loss of reflectivity with relation to the incident radiation in these nanocomposites compared with the pristine polymeric matrix shows the maximum value for the sample with an aluminum content of 10% in volume. Furthermore, the morphological aspects of all the specimens as well as their thermal properties, viscoelastic behavior and dielectric response have been evaluated. The nanocomposite that incorporates an Al content of 10% in volume exhibits the best balance in properties including, in addition to its shielding behavior, its processability and mechanical performance.

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Relaxation processes in crystalline polymers: experimental behaviour — a review

Cited by 617 publications

References 94 publications

Deformation behavior of oriented UHMW-PE fibers

Deformation behavior of oriented UHMW-PE fibers

Relaxational study of poly(vinylpyrrolidone-co-butyl acrylate) membrane by dielectric and dynamic mechanical spectroscopy

Electromagnetic Shielding Features in Lightweight PVDF-Aluminum Based Nanocomposites

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