Issue 39, 2016

Cellulose/boron nitride core–shell microbeads providing high thermal conductivity for thermally conductive composite sheets

Abstract

We fabricated sheets with high thermal conductivity in a way that required less filler. Our approach is as follows: (1) we used core–shell spherical microbeads as the thermally conductive filler; (2) we developed cellulose/h-boron nitride (BN) core–shell spherical microbeads using phase separation of a cellulose xanthate aqueous solution (viscose); (3) we hybridized the cellulose/h-BN core–shell microbeads with epoxy resin using compression molding. This process reduced the amount of h-BN required because the microbeads efficiently formed thermally conductive pathways among the shells in the insulating resin. The thermal conductivities of the resulting sheet in the thickness and in-plane directions were 10.6 and 15.6 W m−1 K−1, respectively, using only 48.5 vol% h-BN. In contrast, the thermal conductivities of the composite sheet with 75 vol% of naked h-BN particles were 6.31 and 22.9 W m−1 K−1 in the thickness and in-plane directions, respectively. This large difference resulted from the anisotropic structure of h-BN. The changes in thermal conductivity with h-BN content were inconsistent with percolation theory, when using the cellulose/h-BN core–shell microbeads as a filler. The thermally conductive sheets fabricated with microbeads exhibited thermal conductivities several times greater than that of sheets fabricated with naked h-BN. This indicated that thermally conductive pathways had formed in the insulating resin.

Graphical abstract: Cellulose/boron nitride core–shell microbeads providing high thermal conductivity for thermally conductive composite sheets

Supplementary files

Article information

Article type
Paper
Submitted
01 2 2016
Accepted
24 3 2016
First published
29 3 2016

RSC Adv., 2016,6, 33036-33042

Cellulose/boron nitride core–shell microbeads providing high thermal conductivity for thermally conductive composite sheets

S. Nagaoka, T. Jodai, Y. Kameyama, M. Horikawa, T. Shirosaki, N. Ryu, M. Takafuji, H. Sakurai and H. Ihara, RSC Adv., 2016, 6, 33036 DOI: 10.1039/C6RA02950G

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