Noise damper and a method for producing a noise damper

A method for producing a noise damper for reducing noise from a vibrating element which vibrates at a vibrational frequency, wherein the noise damper is configured to be in contact with the vibrating element such that when the noise damper is in contact with the vibrating element a noise amplitude at a point in a surrounding of the vibrating element is given by an attenuation factor times the noise amplitude at the point in the surrounding when the noise damper is disconnected from the vibrating element, the method comprising:

• heating an amount of a polymer matrix material such that it melts and forms a melted polymer matrix material;
• dispersing an amount of hollow particles in the melted polymer matrix material;
• wherein each hollow particle has a shell encapsulating a gas filled cavity, and wherein each hollow particle is a temperature expandable particle which is expandable to a size which is temperature dependent;
• elevating the temperature of the melted polymer matrix material with the dispersed hollow particles to a size defining temperature such that the hollow particles expand, wherein the size defining temperature is configured to define the hollow particle size in the solidified polymer matrix;
• shaping and cooling the melted polymer matrix material with the dispersed hollow particles such that the melted polymer matrix material solidifies into a polymer matrix with a shape, the shape comprising a plurality of the hollow particles with a hollow particle size dispersed at a hollow particle concentration in the polymer matrix;
• wherein the amount of polymer matrix material and the amount of hollow particles are configured to define the hollow particle concentration in the solidified polymer matrix,
• wherein the hollow particle size and the hollow particle concentration are configured to set the attenuation factor below an attenuation factor threshold at the vibrational frequency of the vibrating element, the attenuation factor threshold being 0.9,
• the hollow particle size and the hollow particle concentration being further configured such that the polymer matrix with the dispersed hollow particles has a tan delta between 0.1 and 15, wherein tan delta is the loss modulus divided by the storage modulus for a viscoelastic material.