Modeling and Controlling Acoustic Performance of Heterogeneous Materials Made of Recycled Foams

Recycling channels for foam materials, especially mattress foams, are set up. The foams are generally crushed into flakes and then assembled resulting in heterogeneous materials. These materials are more valuable if their properties are controlled. This work focuses on their acoustical properties. First, the properties of initial foams have to be estimated and the assembling process has to be analyzed in order to model the acoustic behavior of the reconstructed heterogeneous materials. The foams flakes are assembled with a binder and compressed during the manufacturing process. This work presents the methodology set up to predict the sound absorption of such heterogeneous materials based on recycled foams, from the estimation of the raw material properties to the final assembly. First, a large number of foams were measured in order to distinguish categories of materials. The data is stored in a database management software in order to perform some statistical analysis. Some typical raw materials are selected and finely characterized in order to create some controlled heterogeneous assemblies. Microscopic analysis and the so called "micro-macro" approach are used to estimate the properties of the binder as well as drawing new compression laws of the foam flakes. The methodology is applied on three heterogeneous assemblies of compressed foams flakes. The main influencing parameters and the key steps of the methodology are drawn in conclusion.