Abstract
A vibration, relatively high frequency, in megahertz range, is generated at the contact portion of rubber composites surface, a rotating tire for example, caused by the microscopic surface unevenness of the opposite object. Viscoelastic properties in high frequency range were measured by using both ultrasonic and conventional dynamic methods. The two methods were compared with several rubber composites. Several carbon black and carbon nanofiber were adopted for nanofillers. As a result, some differences were observed between these two methods on the behavior of storage modulus as well as loss tangent. The reason for the discrepancy between two methods was deduced from the amplitude dependence of composites containing nanofillers. It is shown that the ultrasonic viscoelasticity as a new feature can identify the anisotropy of the composites containing carbon nanofiber.
