Electrospun Micro/nano Fiber Materials For Sound Absorption

The rapid development of the urbanization and industrialization process has made noise pollution a serious problem that threatens human health.It will cause chronic vomiting,indigestion,even vasospasm and high blood pressure.In addition,severe noise pollution would lead to damage of mechanical equipment and buildings.Therefore,controlling noise pollution through effective methods is of great importance.Sound absorption materials are most commonly used for controlling noise which can efficiently dissipate the sound energy by absorption.The traditional sound absorption materials mainly include sound absorption cotton,suspended absorber,perforated plate,sound absorption foam,etc.The nonwoven fiber porous material has been known because of low cost,simple process,and excellent performance.However,the fiber diameter of traditional nonwoven sound absorption materials is mostly micrometer which restricts the improvement of the sound absorption performance.The fiber made by electrospinning technology has the advantages of high porosity,small pore size,large specific surface area,lightweight,which can promote the sound absorption performance because that the effective contact area increases with incident sound wave which increases the friction loss of the material.Herein,PAN was used to fabricate sound absorption materials,the structure and properties of the fiber assembly had been characterized by scanning electron microscope,aperture analyzer and standing wave tube sound absorption test system.It was demonstrated that 13%of PAN was the one that poses better performance.The influence of cavity depth and layer number on sound absorption performance were also investigated,with the increase of cavity depth and number of layers,the maximum sound absorption coefficient moved to lower frequency,reaching 0.637.Different content of SiO₂ nanoparticles were adhered to fibers to form PAN/SiO₂ membrane by blending spinning and SiO₂ coated membranes?SiO₂@PAN?were also prepared.It was determined that the sound absorption performance of 8%PAN/SiO₂ blending membrane?B-SiO₂-8?was better than 1%SiO₂@PAN coating membrane?C-SiO₂-1?when the cavity depth was 25 mm,and they have a maximum sound absorption coefficient of 0.51 and 0.747 respectively.In addition,a PSU fiber material with fluffy and rough structure was constructed in this study.and studied the influence of environment humidity of the 20%PSU fibers on morphology and sound absorption performance.The effect was compared with the performance of PAN and SiO₂ hybrid fiber membranes.It was found that the PSU fiber membrane made in the humidity of 45±5%?PSU-M?with sound absorption performance in the range of 500²500 Hz was better than the 1%SiO₂@PAN coating membrane?C-SiO₂-1?.And the maximum sound absorption coefficient reaches 0.796.The puffy structure and surface roughness of the PSU are beneficial to the exaltation of sound absorption.Finally,the nanofiber membranes were combined with PET needle punched felts,and its performance was comparable to PET needle felts.It was found that the sound absorption performance of composite structures was greater than that of pure PET needle felts.The PSU-M/PET which reaches a maximum value of 0.917 at 1600 Hz,and the thickness only increased by 1/100 but the sound absorption coefficient increased about 3.2 times.The results showed that the composite structure formed by nanofiber materials and traditional nonwoven porous materials helps to improve the sound absorption performance of traditional porous materials at lower frequencies,which is meaningful for noise control.