A new thermographic method for determining the thickness of the polymer surface layer in sound-absorbing fibrous composite materials

Sound absorption efficiency of the fibrous composite material could be increased by an additional polymer thin layer deposited on the substrate. In order to control the thickness of the polymer surface layer, a new method based on thermographic measurement is presented. The proposed method is much easier to use and does not need any expensive tools in contrast to the Optical Coherence Tomography (OCT) image analysis. The research results show the prospects of this method in the development of sound-absorbing composites. The acoustic measurements confirmed that in the case of fibrous composite materials of viscose fibres/polylactide with an additional polylactide surface layer, the nature of low frequency sound absorption depends on the thickness of this layer.