Study On Sound Absorbing Properties Of Layered Composite Spunlaced/ Through Air Thermal Bonded Nonwovens

The textile materials are typical porous materials that having powerful sound absorption ability and can be used as absorber in life. Because of the larger aperture,thinner thickness,the woven and the knitted fabric have a lower sound absorbing performance.There are many researches about nonwovens in the study of textile sound absorbing materials.This paper researched the sound absorbing properties of spunlaced nonwovens and through air thermal bonded nonwovens ,which was made of polyester fibers and stacked into two or three layers.By heating the layered spunlaced nonwovens,hot melt fibre nets and through air thermal bonded nonwovens in the heated dryer, we got the two and three layered composite nonwovens. In this paper, we tested the thickness,air permeability,porosity and other physical properties of the nonwovens before and after compounded to discuss the effect factors of the sound absorbing properties of the nonwoven materials. With the increasing of the thickness,the sound must spread the longer distance to through the materials,so the sound absorption at the same frequency improved. The effect of the air permeability to the sound absorption of single-layer spunlaced nonwovens is not significant;but the sound absorption of through air thermal bonded nonwovens would decrease with the increase of the air permeability. The increase or decrease gradient porosity would serious change the sound absorption of the layered composite nonwovens.In this paper, based on Rayleigh model and the diffusivity equation of sound waves in a medium, we deduced a theoretical sound absorption model for layered composite nonwovens.we had an experimental simulation result and checked it according to the test data of sound absorption.Supported with the experimental and simulation result, we concluded the optimal combination of the layering nonwovens to achieve the best absorption coefficient and draw the conclusion that the model can be used to predict the absorption coefficient in the layered composite nonwovens.