Impedance (Z) = density (rho) x wave speed (c) thus deriving the common term rho/c.
Within the underwater sonar industry, rho-c materials are mainly used to encapsulate and environmentally protect acoustic devices such as transducers and hydrophones. In this case the acoustic impedance of the rho-c material is matched to the acoustic impedance of water, so that signals are transmitted from source to target with minimal reflection and low attenuation.
The correct selection of material depends on the primary requirement – either optimising acoustic matching or providing mechanical and environmental protection for embodied electronics.
Materials are designed (where possible) to have low viscosity to reduce air entrapment and thus allowing encapsulation of complex parts.
In general, softer materials offer better acoustic performance and harder materials provide better protection to the embodied items.
Some transparent materials are available which are particularly useful to allow for the inspection of bubbles within encapsulated parts.
Acoustic Polymers supply a range of rho-c encapsulant materials in bulk or polymer sachet forms.
Polymer sachets provide low volume users with a convenient and easy method of handling and preparing the materials. Reactive constituents are pre-weighed and vacuumed and therefore eliminates the need for any specialist mixing equipment. Sachets are particularly useful for site applications where the provision of power and equipment maybe limited.
We are also able to offer an encapsulation service for electronic components and arrays.