Polythene fine structure

Bryant, W. M. D.

doi:10.1002/pol.1947.120020601

Cited by 145 publications

(24 citation statements)

References 8 publications

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“…Figure 7b shows birefringence data as a function of the concentration of iPB-1 in the blends, which need to be compared with the intrinsic, that is, maximum birefringence. The maximum birefringence is the difference between the indices of refraction parallel and perpendicular to the chain direction and is about one magnitude of order larger than the experimentally observed values [38,39]. Obviously, the different orientation of molecules segments in the PE-LD matrix and in the iPB-1 domains, and the differently oriented two crystal populations of PE-LD, lead to a cancellation of the various contributions to the total birefringence.…”

Section: Resultsmentioning

confidence: 85%

Structure of blown films of polyethylene/polybutene‐1 blends

Nase¹,

Funari²,

Michler³

et al. 2009

Polymer Engineering & Sci

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The structure of blown films of blends of low-density polyethylene (PE-LD) and isotactic polybutene-1 (iPB-1) with different content of iPB-1 was investigated using wide-and small-angle X-ray scattering (WAXS and SAXS), transmission electron microscopy (TEM), and polarizing optical microscopy (POM). TEM proves formation of a matrix-particle phase structure due to immiscibility of the blend components. Within the iPB-1 particles, needle-like crystals with c-axis orientation were observed. The PE-LD matrix showed two populations of crystals. WAXS data indicate that the majority of crystals were oriented with the c-axis perpendicular to machine direction (MD), while SAXS data prove additional presence of stacks of lamellae, oriented parallel to MD. Quantitative birefringence measurements showed that the majority of molecule segments were oriented in the direction of the circumference of the film, confirming the WAXS data. The crystal orientation has direct impact on mechanical properties, which was demonstrated by measurement of the anisotropy of the modulus of elasticity. POLYM. ENG. SCI., 50:249-256, 2010.

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Section: Resultsmentioning

confidence: 85%

Structure of blown films of polyethylene/polybutene‐1 blends

Nase¹,

Funari²,

Michler³

et al. 2009

Polymer Engineering & Sci

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“…1 to the value -o-, = 200 ppm suggests that the same thing can be said for the monoand dihalogen substituted alkanes studied here. It is interesting to note that the limiting value found for the square of the Bayliss-McRae function at this point of convergence, [g(n)] 2 = 0.048, is quite close to the value 0.050 calculated using a refractive index, n = 1.49, which is the value assigned to the index of refraction for amorphous polyethylene [23].…”

Section: Resultsmentioning

confidence: 97%

NMR chemical shifts of129Xe dissolved in liquid haloalkanes and their mixtures

1997

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Xenon-129 NMR spectra have been measured for solutions containing Xe dissolved in a variety of linear 1-haloalkanes, tx,to-dihaloalkanes, and their mixtures. The data are found to be linearly related to solvent composition expressed as volume fraction of the constituent methyl groups, methylene groups, and halogen atoms. This behavior is consistent with a modš in which the large dispersion force contributions to the chemical shift of 129Xe result ti'oro pair interactions between dissolved Xe atoms and the methyl, and methylene groups, and the halogen atom, from which the solvent molecules ate composed.

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“…Much of the following discussion is based on the ''fringed micelle'' model, 69 which was used to describe the crystalline-amorphous nature of poly͑ethene͒. 70 We consider the possibility of structural inhomogeneity on a length scale of nanometers, and assume that the polymer film consists of small crystallite grains in addition to amorphous regions, in which the chains are more widely separated. There is evidence for such structural disorder from electron microscopy studies [71][72][73] of PPV, for which the diameter of crystallite grains is estimated to be in the range 3-12 nm, which is comparable with estimates of the exciton diffusion range.…”

Section: B Structural Disordermentioning

confidence: 99%

Analysis of the photocurrent action spectra of MEH-PPV polymer photodiodes

Harrison

Grüner

Spencer³

1997

Phys. Rev. B

207

103

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We have measured the photocurrent action spectra of the conjugated polymers poly͓2-methoxy, 5 ethyl ͑2Ј hexyloxy͒ paraphenylenevinylene͔ ͑MEH-PPV͒ and poly͑phenylenevinylene͒ ͑PPV͒ in sandwich cells between indium tin oxide ͑ITO͒ and aluminum electrodes. Under forward bias and illumination through ITO, the photocurrent spectrum is broad and has a maximum at high energy, where the absorption coefficient is greatest ͑the symbatic response͒. Under reverse bias and illumination through ITO, the photocurrent spectrum consists of a very narrow peak ͑the full width at half maximum is 0.1 eV͒, located in the low-energy tail of the absorption profile ͑the antibatic response͒. Several established models attempt to explain this behavior and to relate the photocurrent action spectrum to the absorption coefficient, considering penetration depth of the light and diffusion of excitons or directly photogenerated charges. At a qualitative level many of these seem to provide an adequate description. In this paper, we undertake a quantitative examination of these models and we find that none of them can reproduce the very narrow antibatic response that we observe in both MEH-PPV and PPV. Upon exposure to air, we observe an enhancement of the photocurrent by a much greater factor than the dark current, from which we conclude that charge generation is mediated by exciton dissociation. As the temperature decreases we observe a progressive redshift of the absorption edge, although the photocurrent onset undergoes a much smaller redshift. We therefore conclude that the narrow antibatic peak is due to a specific enhancement of dissociation upon excitation at low energy. We propose that the particularly sharp onset of photocurrent at low energy may be due to enhanced intermolecular charge separation within crystallite grains between those neighboring conjugated segments that are more extended and more planar.

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Polythene fine structure

Cited by 145 publications

References 8 publications

Structure of blown films of polyethylene/polybutene‐1 blends

Structure of blown films of polyethylene/polybutene‐1 blends

NMR chemical shifts of129Xe dissolved in liquid haloalkanes and their mixtures

Analysis of the photocurrent action spectra of MEH-PPV polymer photodiodes

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