Studies of the network structure of rubber vulcanizates by a cryoscopic method: 1

The freezing-point depression, ΔT, of swollen dicumene peroxide cured natural rubber in benzene has been measured. The parameter a_H, introduced by Kuhn, which varies inversely as ΔT, should be regarded as an indication of the depression. The anomalous depression is considered to occur due to a non-frozen benzene area formed on the surrounding network chains. From comparison of the scaling law and the experimental results, it was clear that a_H can reflect not only the quantity corresponding to network chain density determined by conventional methods but also the difference in three-dimensional network structure between degraded and undegraded rubber vulcanizates.