Thermal insulation products also have properties such as acoustic insulation. More specifically, these properties are the dynamic stiffness and airflow resistivity.
Sound is transmitted through the air and through solids. Dynamic stiffness is related to impact sound reduction index. The test consists of determining the resonance frequency of a mass-spring system where the spring is the insulating material. The lower the dynamic stiffness value, the higher the sound reduction index of the material.
In the case of air insulation, the airflow resistivity of the material is important, kPa·s/m2. This property is exhibited by fibrous materials such as mineral wool. Resistance to air flow of a material is closely related to its structure and friction of sound waves on the filaments and reduction of the intensity thereof. This avoids it passing through the material. The test subjects the material to a constant air flow, measuring the difference in pressure caused by the material.
Thermal insulation materials to test:
- Expanded polystyrene
- Mineral wool
- Polyurethane foam