5. Conclusions
As the first step in investigating the possibility of employing
polymers as elastomers in high-power ultrasonic applications, we
devised a method for evaluating the mechanical loss in ultrasonic
frequencies and high vibration amplitudes, and we measured the
Q factors of some functional polymers. Based on its original
definition, the Q factor was precisely measured for a bar with suf-
ficiently small thickness. The Q factor decreased as the driving frequencies
and strains increased. At 28.30 kHz, the Q factor of PPS
reached approximately 460 when the strain on the bar was smaller
than 0.005%, which indicated that PPS can be potentially employed
as an elastomer in ultrasonic transducers. In the future, using this
method, we will explore the mechanical loss of other functional
polymers.