No abstract

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.

The dispersion of self-assembled BaTiO 3 (BT) agglomerates in poly-L-lactic-acid (PLLA) polymer matrix was decided with the multifractal analysis to investigate characters of the aggregated morphology of the secondary particle group. On the multifractal analysis, the results showed that the average secondary particle area is increased with increasing the capacity dimension (D 0 ). The average secondary particle area is related to BT agglomerates. It showed that S 1/2 and D 0 plot increased linearity. Therefore, BT agglomerates and D 0 have a correlation. It suggested that D 0 is related to the morphology of the BT agglomerates. The average dielectric constant (ε′) is increased with increasing D 0 . It was considered that the formation of the hetero interface of BT/ PLLA contributed to the increase in the average dielectric constant of BT/PLLA composites.

We report the simulated results for coupled granular and continuous (CGC) films for the thermo assisted magnetic recoding, consisting of FePt particles under layers that act as domain pinning sites of TbFeCo layers. As domain size should be smaller to further increase the recording density, the number of FePt grains has to be decreased in the domain. The simulated results demonstrated that they could be formed in a domain as small as 18.3 nm in diameter, which corresponds to a recording density of 1.8 Tbit/inch 2. Here, three FePt grains were effective for pinning. We also estimated the effective wall coercivity, Hw, from the simulation varying the applied magnetic field until a domain had shrunk and disappeared. The Hw was over 12 [KOe] where there were only three grains for pinning. The Hw was a function of the radius of the curvature at the pinning point and also the inverse average wall length between the pinning points in the same composite films.

Many manufacturers of wooden musical instruments attempt to evaluate timbre of musical instruments. Several quantitative evaluation methods for properties of timbre have been proposed recently. It is, however, difficult to quantify the subtle difference about sounds with musical instruments made of several types of material. In this paper, we develop an evaluation method using a sound waveform analysis. Our method enables us to classify the timbre properties of musical instruments. Finally, we confirmed the validity of our method based on the clustering by psychological evaluation.