Effect of self-assembly material texture and dielectric properties of BaTiO3/poly-l-lactic-acid composites

Yamazaki

Sato

et al. 2022

J. Ceram. Soc. Japan

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In this paper, the properties of the barium titanate (BT)/polyvinylidene fluoride (PVDF) composites were controlled by the self-assembly of the BT secondary particle groups. The self-assembled BT/PVDF composites of 520 vol.% BT were prepared with the difference in the viscosity of polyethylene glycol (PEG) of dispersants involved in the self-assembly process. The multifractal properties and dielectric properties of the self-assembled BT/PVDF composites were investigated with controlling by the formation of the self-assembled BT secondary particle groups. The dielectric constant (¾¤) increased with an increase in the average secondary particle area (S) of the BT particles. The S increased with an increase in the viscosity of PEG; whereas, the ¾¤ decreased with the increase in viscosity. The multifractal analysis indicated that the distribution of self-assembled BT secondary particle groups was affected by PEG viscosity. The sample with PEG1000 had aggregates with a BT/PVDF/BT heterointerface, the sample with PEG20000 had agglomerates with a BT/BT interface, and the sample with PEG2000 had both, aggregates and agglomerates. The BT/PVDF/BT heterointerface in the BT aggregates played an important role in improving the dielectric properties of the BT/PVDF composites. Overall, the viscosity of the dispersant affected the self-assembly process as well as the ¾¤. It was suggested that the multifractal properties and dielectric properties were controlled by the self-assembly of the BT secondary particle groups.

Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Effect of dispersant viscosity for self-assembly process of barium titanate aggregates in material texture of polyvinylidene fluoride composites —evaluation of multifractal dimension (Dq [q = 0, 1, 2]) and dielectric properties—

Yamazaki

Sato

et al. 2022

J. Ceram. Soc. Japan

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“…Munakata et al 4) highlighted that the dielectric constant of the BT/PLLA composites and the size of the selfassembled BT secondary particle groups. In a previous report, 8) the morphology of the self-assembled BT secondary particle groups was affected by the kneading speed.…”

Section: Introductionmentioning

confidence: 99%

Effect of ceramics/polymer heterointerface on dielectric property of self-assembled BaTiO3/poly-L-lactic acid composite materials

Yoshino

Ito

et al. 2021

J. Ceram. Soc. Japan

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The dispersion state of barium titanate (BT) particle groups in self-assembled BT/poly-L-lactic-acid (PLLA) composites prepared under different fabrication conditions was investigated. In particular, the BT/PLLA/BT heterointerface in the BT aggregates by the self-assembly process was analyzed and the effect of the BT/PLLA/ BT heterointerface and the BT/BT interface on the dielectric properties of BT/PLLA composites were investigated. BT/PLLA composites were fabricated by adding BT particles and BT granules with low and high-speed kneading conditions. The volume fraction of BT in composites varied from 5 to 20 vol.%. The BT aggregates having a BT/PLLA/BT heterointerface were formed under the low-speed kneading condition and the BT agglomerates having a BT/BT interface were formed under the high-speed kneading condition within the selfassembly process. The tan ¤ of the BT/PLLA composite of self-assembled BT aggregates having the BT/PLLA/ BT heterointerface was lower than that of the BT granules having the BT/BT interface. The dielectric constant (¾¤) of the self-assembled composite was increased by growing an average secondary particle area of BT fillers. In contrast, the average secondary particle area of BT granules was increased, as compared with 5 vol.% of BT. However, the change in ¾¤ was saturated. The slopes of the change in the ¾¤ depending on the secondary particle area of BT fillers were different between the self-assembled BT aggregates having the BT/PLLA/BT heterointerface and the BT granules having the BT/BT interface. Thus, it was suggested that it was an important role in improving the dielectric properties to form ceramic secondary particle groups having the ceramics/polymer/ceramics heterointerface by the self-assembly process.

“…1 Recently, we reported the effects of kneading conditions and additives on the dispersion of BaTiO 3 ceramic fillers and found they influenced the dielectric constant ε of the Ba-TiO 3 /poly-L-lactic-acid composites. 2 Consequently, a selfassembled structure may have been produced owing to the control of the electrostatic interactions between the polymer and electrostatic ceramic filler. In the studied system, selfassembly may result from electrostatic interactions, especially in reaction processes involving solids.…”

Section: Introductionmentioning

confidence: 99%

“…Scanning electron microscopy (SEM) images of the composites showed that the abovementioned dielectric constant increased as the average secondary particle area of the BaTiO 3 filler aggregate increased. 2 Meanwhile, the representative 316L stainless steel (SUS316L) has favorable corrosion resistance, mechanical property, and weldability. However, the thermal conductivity of SUS316L is approximately 15 W m À1 K À1 , which is 1/5 of that of iron.…”

Section: Introductionmentioning

confidence: 99%

Self-assembly process under a solid-state reaction of β-Si₃N₄/austenitic stainless-steel composites: stirring conditions and material texture

Munakata

Ookubo

Journal of Composite Materials

et al. 2021

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In the self-assembly process of β-Si3N4 (SN)/316L stainless-steel (SUS316L) composite materials tailored via sintering of powder mixtures, the formation of a SN agglomerate resulting from condensation–dispersion reactions during the stirring of SN/SUS316L was found to play an important role in improving the thermal conductivity. Moreover, the obtained SN secondary particle groups connected to form a network through diffusion-limited aggregation. In particular, it was shown that the sample prepared at the milling speed of 150 r/min has a similar particle group area (about 1.38 μm2) to that at 120 r/min, but a higher κ (increased from 9.5 W m−1 K−1 to 11.5 W m−1 K−1). To quantitatively evaluate the microstructural morphology of the texture of the self-assembled composite material, global parameters τ( q) and D q and local parameters α( q) and f( α) were determined via multifractal analysis. These characteristics of the anisotropy, dispersion, and cohesiveness of the particle network in the material texture could be analyzed together with the capacity dimension D0, information dimension D1 (configuration entropy), correlation dimension D2, and α( q) (related to internal energy). The results suggest that α( q) reflects the differences in the cohesion of the additive particle agglomeration that constitutes the self-assembly process under the solid-state reaction.