doi:10.3850/978-981-07-0319-6_238

ABSTRACT

The acoustic and micro-elastic properties of water-immersed Nafion NRE-212 membranes were investigated by analyzing the images obtained from vector contrast scanning acoustic microscopy operated at 400MHz. The magnitude of the grey levels in a maximum amplitude image obtained by the acoustic microscope operated in reflection is exploited to measure the acoustic impedance of the sample with the spatial resolution of the instrument. For the quantitative evaluation of the acoustic impedance, calibration was done with a soda-lime microscope glass slide sample of known acoustic properties and comparison to an already studied chitosan film sample. The evaluated acoustic impedance of 2.25 ± 0.03 MRayls relates to a longitudinal velocity of sound of 1142 ± 15 ms^-1 in the immersed Nafion membrane. This enables, using the appropriate values for Poisson’s ratio, the calculation of the Young’s modulus at 194 ± 5 MPa for the immersed Nafion membrane. We present a non-destructive characterization technique for the determination of the elastic properties of the Nafion NRE-212 membranes.

Keywords: Nafion membrane, Acoustic microscopy, Maximum amplitude image, Acoustic impedance, Young’s modulus.

© 2011 4M 2011 Organisers