English Abstract

Structure and Property Relationship in Nano-filler Loaded Cross-linked Rubbers
3. Relationship Between Optical Transparency and Filled Silica Networks in Natural Rubber Vulcanizates

Atsushi KATO *1
Yuko IKEDA *2
*1:Department of Materials Analysis, NISSAN ARC, LTD., Yokosuka, Kanagawa, Japan
*2:Graduate School of Science and Technology, Kyoto Institute of Technology, Matsugasaki, Kyoto, Japan
Nippon Gomu Kyokaishi,(2014),87(8),351-357 General Review in Japanese

Relationship between an optical transparency and a filler loading in cross-linked rubber is reviewed using our results of hydrophilic and hydrophobic silica-filled peroxide cross-linked natural rubbersiNRsj. The loading of hydrophilic silica shows an optical anomaly, in which the optical transparency initially decreases and then increases with increasing an amount of the loading. The optical transparencies of the hydrophobic silica filled samples, on the other hand, are almost same without depending on the amounts. The difference is ascribed to characteristics of silica networks in these samples, which are revealed by three-dimensional transmission electron microscopy. With an increase of isolated filler chains in the rubber matrix, the optical anomaly of hydrophilic silica-filled cross-linked NR is found to be significantly accelerated. Light scattering equation is also formulated using a product of the number density and squared length of the isolated chains to explain the differences.

Keywords: 3D-TEM, Natural Rubber, Peroxide Cross-linking, Transparency, Hydrophilic Silica, Hydrophobic Silica, Filler Network