Table of Contents
ISRN Materials Science
Volume 2011, Article ID 718761, 10 pages
http://dx.doi.org/10.5402/2011/718761
Review Article

Thermal Conductivity of High-Strength Polyethylene Fiber and Applications for Cryogenic Use

1Research Center, Toyobo Co., Ltd., 2-1-1, Katata, Ohtsu, Shiga 520-0292, Japan
2Faculty of Science and Technology, Sophia University, 7-1, Kioi-Cho, Chiyoda-Ku, Tokyo 102-8554, Japan

Received 6 July 2011; Accepted 25 July 2011

Academic Editors: C. Carbonaro and F. Herlach

Copyright © 2011 Atsuhiko Yamanaka and Tomoaki Takao. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The local temperature rise of the tape is one of instabilities of the conduction-cooled high temperature superconducting (HTS) coils. To prevent the HTS tape from locally raising a temperature, high thermal conductive fiber reinforced plastic was applied to coil bobbin or spacer for heat drain from HTS tape. The thermal conductivity of ramie fibers increases by increasing orientation of molecular chains with drawing in water, and decreases by chain scission with γ-rays irradiation or by bridge points in molecular chains with vapor-phase-formaldehyde treatments. Thermal conductivity of high strength ultra-high-molecular-weight (UHMW) polyethylene (PE) fiber increases lineally in proportion to tensile modulus and decreases by molecular chain scissions with γ-rays irradiation. This result suggested the contribution of the long extended molecular chains due to high molecular weight on the high thermal conductivity of high strength UHMW PE fiber. Thermal conductivity of high strength UHMW PE fiber reinforced plastics in parallel to fiber direction is proportional to the cross sectional ratio of reinforcement oriented in the conduction direction. Heat drain effect of high strength UHMW PE fiber reinforced plastic from HTS tape is higher than that of glass fiber reinforced plastic (GFRP) and lower than that of aluminum nitride (AlN). In the case of HTS coil, the thermal stability wound on coil bobbin made of high strength UHMW PE fiber reinforced plastic is good as that of AlN, and better than that of GFRP.