Effect of Glass Transition on Electrical Conduction Characteristics of Poly-L-lactic Acid

Maeno, Y.; Yamaguchi, Yuya; Hirai, Naoshi; Tanaka, Toshikatsu; Ohki, Yoshimichi; Kohtoh, M.; Okabe, Shigemitsu

doi:10.1541/ieejfms.125.254

Cited by 21 publications

(18 citation statements)

References 12 publications

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“…Since T g is about 60 °C for all the samples, the TSPC peak is attributable to the alignment of dipole moments due to the commencement of micro-Brownian motion associated with the glass transition. This dielectric relaxation is called segmental-mode relaxation, for which dipoles with a direction perpendicular to the chain contour in the amorphous region are responsible [1,12]. Since PLLA has a carbonyl group in each repeating unit of its chemical structure, the relaxation should be attributable to carbonyl groups.…”

Section: Relation Between Conduction Current and Crystallinitymentioning

confidence: 99%

“…Among many biodegradable polymers, poly(L-lactide) (PLLA) is superior in mechanical and thermal properties. Therefore, its electrical properties and degradation behavior have been examined in order to evaluate its applicability to electrical insulation [1][2][3][4][5][6]. In the present article, we examine the effects of crystallinity on the electrical conduction and dielectric relaxation of PLLA.…”

Section: Introductionmentioning

confidence: 99%

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Effects of crystallinity on dielectric properties of poly(L‐lactide)

Hikosaka

Ishikawa

Ohki

2011

Elect Comm in Japan

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SUMMARYPoly(L-lactide) is attracting much attention as a biodegradable polymer. In this paper, effects of crystallinity on dielectric properties of PLLA are discussed. At 80 $C, which is above the glass transition temperature (= about 60°C ), the conductivity increases with a decrease in crystallinity. A thermally stimulated polarization current (TSPC) peak, which seems to be due to segmental-mode relaxation, appears in all the samples at temperatures around 65 to 70°C, and it becomes smaller as the crystallinity increases. All the samples show two thermally stimulated depolarization current (TSDC) peaks at around 65 °C and around 90 to 100°C. The lower-temperature peak seems to be due to the segmental-mode relaxation, and the other due to the normal-mode relaxation. Moreover, all the samples show a drastic increase in the real part of the complex permittivity (ε r g ) and a peak in its imaginary part (ε r .) at frequencies from 10 -1 to 10 4 Hz, depending on the measurement temperature. The crystallinity dependencies of the two parts are similar to those of the TSPC and TSDC peaks at around 65 to 70°C. Therefore, the increase in ε r g and the peak in ε r gg are ascribable to the segmental-mode relaxation.

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Section: Relation Between Conduction Current and Crystallinitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of crystallinity on dielectric properties of poly(L‐lactide)

Hikosaka

Ishikawa

Ohki

2011

Elect Comm in Japan

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“…Since the biodegradable polymers are polar polymers and contain a large number of carbonyl groups, they have high values of ε r . It is also a well-known fact that due to microbrownian motion in the rubbery-state materials, in polymers having a high concentration of polar groups, such as PLLA and polyamide-6, ε r of the rubbery state is higher than that of the glass state [3,10]. Therefore, it is logical that ε r of the rubbery polymeric materials, such as PCL-BS and PBS, is high.…”

Section: Characteristics Of the Samplesmentioning

confidence: 99%

“…At the present time, the majority of widely used solid insulating materials are difficult to recycle and, when disposed, contribute to global warming and soil contamination. Recently, attention was drawn to biodegradable polymers which, when buried in the ground, are decomposed by microorganisms thus reducing the stress to the environment and biological systems [1][2][3][4][5][6]. One such polymer, poly-L-lactic acid (PLLA), is successfully used for fabrication of components of motor vehicle interiors, for packaging of electric appliances, etc.…”

Section: Introductionmentioning

confidence: 99%

“…At the present time, PLLA insulation is used in the test production of low-voltage electric cables [2]. Therefore, we have started fundamental research on various basic dielectric properties of several biodegradable polymers including PLLA, and compared them with characteristics of polyethylene (PE), a typical polymer [1,[3][4][5]. In this article, we report results of our studies of resistance to partial discharge (PD) of biodegradable polymers under a constant AC voltage.…”

Section: Introductionmentioning

confidence: 99%

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Partial discharge degradation of several biodegradable polymers

Fuse

Fujita

Hirai

et al. 2009

Electrical Engineering Japan

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SUMMARYPartial discharge (PD) resistance was examined by applying a constant voltage to four different biodegradable polymers-poly-L-lactic acid (PLLA), polyethylene terephthalate succinate (PETS), poly ε-caprolactone butylene succinate (PCL-BS), and polybutylene succinate (PBS)-and the results were compared with those of low-density polyethylene (LDPE) and crosslinked low-density polyethylene (XLPE). The PD resistance is determined by the erosion depth and the surface roughness caused by PDs, and is ranked as LDPE ≈ XLPE > PLLA ≈ PETS > PBS > PCL-BS. This means that the sample with a lower permittivity has better PD resistance. Furthermore, examination of the sample surfaces by a polarization microscope and a laser confocal microscope reveals that the PD resistance of crystalline regions with spherulites is higher than that of amorphous regions. Therefore, good PD resistance can be achieved by the sample with a high crystallinity and a low permittivity.

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Electrical conduction and dielectric relaxation in polyethylene terephthalate succinate

Kato

Ohki

2009

Electrical Engineering Japan

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SUMMARYElectrical conduction and complex permittivity are examined in polyethylene terephthalate succinate, focusing on their relations to dielectric relaxation processes. Both the real and imaginary parts of the complex permittivity, namely, the dielectric constant ε r g and the dielectric loss factor ε r gg , increase with a decrease in frequency, especially at high temperatures. They are both ascribed to the transport of ionic mobile carriers. Namely, the carrier transport forms a conduction current that should contribute to ε r gg . On this occasion, if charge exchange does not occur at the two electrodes, heterocharge layers should be formed before the electrodes. This should increase the charge density on the electrodes, thus contributing to ε r g . In addition to the increase in ε r g and ε r gg due to mobile ions, two relaxation processes, one due to micro-Brownian motion of dipoles and the other due to orientation and magnitude change of the dipole moment induced by two end groups in the polymer main chain, are observed. Corresponding to these two relaxation processes, two thermally stimulated discharge current (TSDC) peaks appear. The two TSDC peaks as well as the increments in ε r g and ε r gg become larger when the crystallinity of the sample decreases.

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Effect of Glass Transition on Electrical Conduction Characteristics of Poly-L-lactic Acid

Cited by 21 publications

References 12 publications

Effects of crystallinity on dielectric properties of poly(L‐lactide)

Effects of crystallinity on dielectric properties of poly(L‐lactide)

Partial discharge degradation of several biodegradable polymers

Electrical conduction and dielectric relaxation in polyethylene terephthalate succinate

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