Identification and characterisation of materials by broadband ultrasonic attenuation analysis

Abstract Ultrasound attenuation analysis has been demonstrated as a cheap, reliable method of identifying and characterising polymeric materials and components, which can assist in the separation and reclamation of thermoplastics from polymer waste streams. Material/Component broadband ultrasonic attenuation measurement, and the measurement of the time of flight of an ultrasonic pulse, in either pulse echo or pulse through transmission mode, can be combined to attain a signature of the material under investigation. The HL (Hull/Langton) signature is independent of component dimensions, and hence, is a powerful tool for the identification of components of complex shape where access to all surfaces may be restricted. The results presented demonstrate the ability of the technique to identify a range of different polymers, including reinforced materials. The approach adopted is not confined solely to polymers, but can also be used to identify the levels of porosity in ceramic pottery, including both open and closed cell pores.