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Two‐Phase Network Formation in Sulfur Crosslinking Reaction of Isoprene Rubber
Author(s) -
Yasuda Yoritaka,
Minoda Shinya,
Ohashi Takumi,
Yokohama Hiroyuki,
Ikeda Yuko
Publication year - 2014
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201400066
Subject(s) - isoprene , natural rubber , zinc , stearic acid , vulcanization , zinc stearate , polymer chemistry , sulfur , network structure , chemistry , materials science , chemical engineering , composite material , organic chemistry , copolymer , raw material , machine learning , computer science , engineering , polymer
Synchrotron in situ zinc K ‐edge X‐ray absorption near‐edge structure measurements are conducted during sulfur crosslinking reactions of isoprene rubber at 140 °C. A two‐phase network formation via two different reactions is revealed in a benzothiazolesulfenamide‐accelerated curing system with zinc oxide and stearic acid. DSC measurements support this observation. The results are in good agreement with previous work using small‐angle neutron scattering, where network domains of high network‐chain density are proposed to be embedded in a mesh network. A formation of the mesh network is found to occur a little earlier than that of the network domains, and its fraction is unexpectedly observed to be larger than that calculated on the basis of a concentration of zinc stearate. The result is ascribable to amounts of zinc intermediates forming the mesh network. This study may be the first in situ evaluation for the inhomogeneous network formation during vulcanization.