English Abstract

Multiple Structural Changes Found around Crack Tip of Carbon Black-filled Natural Rubber Vulcanizate

Masatoshi TOSAKA *1
Takayuki MARUYAMA *2
*1:Institute for Chemical Research, Kyoto University, Uji, Kyoto, Japan
*2:Bridgestone Corporation, Kodaira, Tokyo, Japan
Nippon Gomu Kyokaishi,(2019),92(5),171-173 Original Paper in Japanese

Structure changes around the crack tip of natural rubber vulcanizates filled with carbon-black were investigated after a cycle of stretch-retraction. On the extension line of the crack, formation of a valley-like dent was newly found.The depth of the dent was about 10 μm. By the diffraction mapping using the micro X-ray beam, localization of crystals of paraffin, which has been mixed as plasticizer, along the valley-like dent was disclosed. These findings indicate the occurrence of large-scale mass transfer which leads to three-dimensional transformation and segregation of the low molecular weight material along with the strain-induced crystallization around the crack tip.

Keywords: X-ray Diffraction, White Light Interferometric Optical Microscope, Reinforcement