| English Abstract |
| Studies on Structures and
Dynamic Properties of Peroxide-Crosslinked EPDMs, Part 3 Changes in Molecular Mobility and Crosslinking Density Caused by Carbon Black Hitoshi Iwabuki Industrial Technology Center of Okayama Prefecture, Okayama,Japan Kazuya Nagata Industrial Technology Center of Okayama Prefecture, Okayama,Japan Toru Noguchi Nissin Kogyo Co., Ltd, Nagano,Japan Eisuke Yamada Aichi Institute of Technology, Aichi,Japan Nippon Gomu Kyokaishi,(2003),76(12), 429-435 Original Paper in Japanese. Abstract Peroxide-crosslinked EPDMs filled with various kinds of carbon black (CB) were examined by  pulsed
NMR. The signal of spin-spin relaxation time (T2)
measured by Hahn echo method was resolved into two components, T2n
and T2nn, which correspond to the network molecules
and the non-network molecules respectively. For the non-crosslinked EPDMs
filled with CB, T2n and T2nn
became shorter with the increase in the specific surface area of CB, though
the degree of the decrease in the molecular mobility was smaller in the
case of the network component. For the crosslinked EPDMs, T2n
and T2nn became longer with the increase in the
specific surface area of CB, suggesting that the presence of the CB obstructs
the crosslinking. The crosslinking density of rubber phase ( )
were calculated from the relationship between the apparent crosslinking
density ( )
and the reciprocal of T2n (1/T2n)
for unfilled EPDMs. The crosslinking density related to CB ( )
were obtained from the difference between
and
for CB-filled EPDMs. The
values showed good correlation with the tensile stress at 100% elongation.
Keywords: EPDM, Peroxide, Carbon black, Pulsed NMR, Hahn echo method, Molecular mobility, Crosslinking density |
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