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|Title:||Thermal destruction of carbon black network structure in natural rubber vulcanizate|
NISSAN ARC, LTD.
Kyoto Institute of Technology
|Citation:||Journal of Applied Polymer Science. Vol.122, No.2 (2011), 1300-1315|
|Abstract:||To investigate thermal destruction and rearrangement of the carbon black (CB) network consisting of CB aggregates in rubbery matrix, the proper heat-treatment temperature without thermal decomposition of rubber matrix were examined by using differential scanning calorimetry, dynamic mechanical measurements, and thermal expansion measurements. 383 K was chosen as the heat-treatment temperature under vacuum. The volume resistivity (P v ) of 50 phr CB-filled natural rubber vulcanizate (CB-50) increased rapidly up to a heat-treatment time of 24 h and it decreased by further heat-treatment time, whereas the P v of CB-80 remained almost constant without depending on heating time. Three-dimensional electron microscope (3D-TEM) observations revealed that after the heat-treatment for 75 h, the average lengths of the crosslinked and the branched chains and the crosslinked points density (D cross ) of the CB network decreased, whereas the branched points density (D branch ) increased with decrease of D cross . After the heat-treatment, their fractions (F cross ′s) of crosslinked chains decreased, whereas their fractions (F branch ′s) of the branched ones increased. Especially, F branch of CB-50 became larger than that of CB-80, while the decrease of F cross of CB-50 was almost the same as that of CB-80 by the heat-treatment. And, F cross and F branch of the heat-treated CB-50 were the same compositions (F cross and F branch = ca. 0.7 and ca. 0.3, respectively) as those of the heat-treated CB-80. It is suggested that the CB network of CB-80 is more therma l stable than that of CB-50. These results directly indicate that CB network is broken and is rearranged by a heat-treatment. © 2011 Wiley Periodicals, Inc.|
|Appears in Collections:||Scopus 2011-2015|
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