Ｌ型ポリ乳酸の結晶化度が誘電特性に与える影響

Electrical Engineering Japan

Fukunaga

Mizuno

et al. 2016

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SUMMARYNowadays, trials to use even higher frequencies are pursued to realize high-speed wireless communications. In order to respond to such a trend, dielectric properties of insulating polymers at high frequencies have to be clarified, although the importance of clarifying low-frequency properties is still very high, especially for use as high-voltage insulators. In this regard, complex permittivity spectra from 10 mHz to 4.0 THz were obtained for various insulating polymers. The spectra obtained in the very wide frequency range are important, because they can be a valuable database and they provide various pieces of important information on dielectric characteristics. C⃝ 2016 Wiley Periodicals, Inc. Electr Eng Jpn, 198(3): 11-18, 2017; Published online in Wiley Online Library (wileyonlinelibrary.com).

Section: Discussionmentioning

confidence: 99%

Complex Permittivity Spectra of Various Insulating Polymers at Ultrawide‐Band Frequencies

Electrical Engineering Japan

Fukunaga

Mizuno

et al. 2016

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“…Various practically important properties such as the mechanical strength, dielectric permittivity, electrical conductivity, and chemical resistance of crystalline polymers are known to depend generally on their crystallinity or the ratio of crystalline parts in the whole volume. [11][12][13] The crystallinity can be changed by various treatments such as thermal annealing and mechanical stretching. Compared with PET, PEN is a new engineering polymer manufactured only in Japan.…”

Section: Introductionmentioning

confidence: 99%

Crystallinity of poly(ethylene naphthalate) and its relation to terahertz absorption

Odaka

Mizuno

2017

Jpn. J. Appl. Phys.

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The crystallinity of poly(ethylene naphthalate) (PEN) was changed by thermal annealing and its effects on terahertz absorption spectra and X-ray diffraction patterns were examined. As a result, the intensity of a relatively sharp absorption peak at around 2.2 THz was found to be proportional to the crystallinity. As a plausible cause of this absorption, a lattice vibration, a torsional vibration, or their combination mode associated with (010) planes in crystal α of PEN is proposed. Therefore, the crystallinity of PEN can be estimated from the intensity of this absorption.

“…This means an increase in " 0 r , since the potential difference between the electrodes remains unchanged. [9][10][11][12][13][14] On the other hand, " 0 r decreases monotonically with an increase in T at frequencies above about 1.0 Hz for all the samples. Generally, the appearance of d" 0 r =dT < 0 is caused by two mechanisms.…”

Section: Resultsmentioning

confidence: 99%

Estimation of thermal expansion coefficients of polymeric insulating films from temperature dependence of dielectric permittivity

Takihana

2014

Jpn. J. Appl. Phys.

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A parallel array of isolated metal nanowires is expected to be hydrophilic. We show, however, that a clustering of such nanowires brought about by vacuum drying produces a 'dual-scale roughness' and confers a strongly hydrophobic property to the surface. The mean size of the nanowire clusters as well as the contact angle are both found to be related to the wire length, and the critical wire length above which the surface becomes hydrophobic is ≈10 μm. Surface roughness is generally known to enhance water-repellent properties, but this is the first report of roughness-induced hydrophobicity on a bare (uncoated) metallic surface.