Frequency-Independent and Frequency-Dependent Polymer Transitions on FlexuralPlate Wave Devices and their Effects on Vapor Sensor Response Mechanisms

摘要

The flexural plate wave device is capable of sensing transition behaviors ofhomogeneous amorphous polymers applied as thin films to its surface. The changes in polymer properties at the static glass transition temperature are sensed as a change in slope of the frequency-temperature plot. Frequency-dependent relaxation properties are detected with a sigmoidal change in slope of the frequency-temperature plot and a minimum in signal amplitude. The transitions observed using poly(vinyl propionate) are correlated with the properties of these polymers known by independent methods. The responses of the flexural plate wave device at 5 MHz are in accord with the results of ultrasonic experiments at similar frequencies. The effects of polymer relaxation processes on the performance and selection of sorbent polymers on acoustic vapors sensors are discussed.