English Abstract
Heat Resistance of Silica Filled Vulcanizates of Natural Rubber
Soji Kodama
Okayama Ceramics Research Foundation,Okayama,Japan
Division of Materials Science, Graduate School of Science and Technology, Nagasaki University,Nagasaki,Japan
Katsushi Nishi
Industrial Technology Center of Okayama Prefecture,Okayama,Japan
Hitoshi Iwabuki
Industrial Technology Center of Okayama Prefecture,Okayama,Japan
Mutsuhisa Furukawa
Division of Materials Science, Graduate School of Science and Technology, Nagasaki University,Nagasaki,Japan
Nippon Gomu Kyokaishi,(2003),76(
11), 393-398 Original Paper in Japanese.


Abstract
The heat aging behavior of silica filled natural rubber vulcanizate was compared with that of carbon black filled vulcanizate, using an air oven operating at 100Ž. In the absence of antioxidant, the reduction rate in tensile strength (TB) of the silica filled vulcanizate during the aging test was found to be similar to that of the carbon black filled vulcanizate. In the case of elongation at break (EB), the reduction rate of the carbon black filled vulcanizate was higher than that of the silica filled vulcanizate. In the presence of an antioxidant, the decrease in TB and EB of the silica filled vulcanizate was very much lower than that of the carbon black filled vulcanizate. In addition to the conventional protection against chain scission and crosslink breakage of the polymer during thermal aging, the antioxidant in the silica filled vulcanizate appeared to have also changed the crosslinking structure of the polymer, as shown by the changes in sol content. Acrosslinking density and structure. It seemed that the silanol group on silica surface could activate the antioxidants, such as 2-mercaptbenzimidazole(MBI) to function as a secondary antioxidant.

Keywords:
Natural rubber, Heat resistance, Silica, Carbon black, Antioxidant
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