IngentaConnect Acoustic properties of butadiene and silicone elastomers at megah...

Authors: Burke, M.P.¹; Smith, J.D.²; Carroll, N.L.³; Townend, D.J.⁴; Porter, D.⁴; Hoskins, P.R.⁵

Source: Plastics, Rubber and Composites, Volume 38, Number 8, October 2009 , pp. 343-348(6)

Abstract:

A tissue mimic material with a sound velocity of 1540 m s^-1 and an acoustic attenuation of 0·5 dB MHz^-1 cm^-1 is required for calibrating medical Doppler ultrasound transducers. These properties can be obtained with a solid material comprised of a gel containing a high water content. If solid elastomers are to be used to provide a more stable tissue mimic, modelling suggests that the materials would require low viscoelastic damping, with a low glass transition temperature, T_g. Castable polyurethanes have been made using a polybutadiene soft segment and by adding process oil, the acoustic loss has been reduced to 0·9 dB MHz^-1 cm^-1 with a sound velocity of 1459 m s^-1. Unfilled butadiene rubber (with a high-cis microstructure) had an acoustic loss around 1 dB MHz^-1 cm^-1, the low loss being associated with its low T_g, with a sound velocity of 1567 m s^-1. Silicone elastomers made from unfilled poly dimethyl siloxane had an acoustic loss of 0·71 dB MHz^-1 cm^-1, but the sound velocity was too low at 1033 m s^-1. Filler particles were added to raise the sound velocity, but they seemed to act as scattering centres and the composite had high acoustic attenuation. None of the elastomers were able to reproduce the acoustic attenuation characteristics of the tissue mimic gel.

Keywords: BUTADIENE RUBBER; ULTRASONICS; ACOUSTICS; DYNAMIC PROPERTIES

Document Type: Research article

DOI: 10.1179/146580109X12473409437020

Affiliations: 1: QinetiQ Farnborough, Room 2057, Building A7, Ively Road, Farnborough, GU14 0LX, UK;, Email: mpburke@qinetiq.com 2: DSTL Porton Down, Room 16, Building 352, Salisbury SP4 0JQ, UK 3: QinetiQ Winfrith, Room 109, Building A22, Winfrith Technology Centre, Dorchester, DT2 8XJ, UK 4: Formerly DERA Farnborough, UK 5: Medical Physics, University of Edinburgh, Edinburgh, UK

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Acoustic properties of butadiene and silicone elastomers at megahertz frequencies