Two-component materials are synthesized to overcome limitations of single-component materials.

A recently invented family of acoustic-damping materials offers advantages over prior acoustic-damping materials:

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  Relative to soft rubbers and the like previously used for acoustic damping, these materials have high moduli of elasticity; that is, these materials are stiffer and, therefore, better suited for applications in which some stiffness is required.

   

   

• One prior acoustic-dumping material contains lead and is produced by casting into blocks that must then be machined to desired sizes and shapes. The release of lead particles during machining poses a toxicity hazard. In contrast, the present materials have little toxicity and can be cast in molds to final sizes and shapes, without machining.

It is not been possible to obtain a desired combination of high modulus of elasticity (E) and high damping in a rubber or a similar single-component material for the following reasons:

• A rubber or similar material typically undergoes a glass-to-rubber transition in a temperature range characterized by a middle temperature T_g (denoted the glass-transition temperature). It is well established that such a material dissipates vibrations more effectively at T_g than at higher or lower temperature but also tends to be relatively soft (to have low E) at T_g.
• It is also well established that the rate at which acoustic energy enters the material is proportional to E^1/2. Hence, if a material has low E, it may not absorb acoustic energy at a rate high enough to be considered an efficient damper, even at T_g.