Entropic and Energetic Elasticities of Natural Rubber with a Nanomatrix Structure
- Yoshimasa YamamotoYoshimasa YamamotoDepartment of Chemical Science and Engineering, National Institute of Technology, Tokyo College, 1220-2, Kunugida-cho, Hachioji, Tokyo 193-0997, JapanMore by Yoshimasa Yamamoto,
- Kota EndoKota EndoDepartment of Materials Science and Technology, Nagaoka University of Technology, 1603-1, Kamitomioka-cho, Nagaoka, Niigata 940-2188, JapanMore by Kota Endo,
- Quentin TévenotQuentin TévenotDepartment of Materials Science and Technology, Nagaoka University of Technology, 1603-1, Kamitomioka-cho, Nagaoka, Niigata 940-2188, JapanMore by Quentin Tévenot,
- Kenichiro KosugiKenichiro KosugiDepartment of Materials Science and Technology, Nagaoka University of Technology, 1603-1, Kamitomioka-cho, Nagaoka, Niigata 940-2188, JapanMore by Kenichiro Kosugi,
- Ken NakajimaKen NakajimaDepartment of Chemical Science and Engineering, Tokyo Institute of Technology, O-Okayama, Meguro, Tokyo 152-8552, JapanMore by Ken Nakajima, and
- Seiichi Kawahara*
The entropic and energetic elasticities of natural rubber with a nanomatrix structure are investigated by measuring the viscoelastic properties of deproteinized natural rubber (DPNR)-graft-polystyrene (PS). A nanomatrix structure is formed by graft copolymerization of styrene onto the surface of natural rubber particles, followed by coagulation. The morphology of the nanomatrix structure is observed with transmission electron microscopy. Natural rubber particles with about 1 μm diameter are well dispersed in a nanomatrix of PS. The horizontal shift factor (aT) and vertical shift factor (bT) are determined by superposition to create a master curve according to the time–temperature superposition principle. The positive slope of DPNR appears in the plot of bT versus temperature, suggesting that entropic elasticity occurs. In contrast, the slopes of DPNR-graft-PS are negative at lower temperatures but positive at higher temperatures. The negative slope, which suggests entropic elasticity, may be attributed to the formation of a nanomatrix structure. Natural rubber with a nanomatrix structure realizes both energetic elasticity and entropic elasticity.
This article is cited by 3 publications.
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