Absorption Coefficient And Structure Of High Performance Sound Absorption Materials

Nowadays,noise has become one of the most severe environmental issues along with atmospheric pollution,water pollution and solid waste pollution.With the development and mechanization of agriculture,industry and transportation system,noise pollution has become more and more serious.Thus,sound absorption industry is given more and more attention and the needs and requirements of sound absorption materials explode.From the recent research,it is found that sound absorption materials has great sound-absorbing performance at high frequency noise,but at low frequency,the sound-absorbing performance turns out to be poor.How to improve the sound-absorbing performance at low frequency noise has become the hot spot at sound absorption industry.In this research,electrospinning process has been researched firstly.The process parameters have great influence on the morphology of electrospinning nanofibers.Polymer solution properties such as viscosity,surface tension and electric conductivity are the main factors that can affect the morphology of electrospinning nanofibers.With the changes of polymer weight and solution concentration,solution properties get changes so as nanofibers morphology.It is found that nanofibers diameters increase with the increase of polymer molecular weight and its solution concentration.Droplet formation plays an important role on the free wire surface electrospinning to make nanofiber.The size of polymer solution droplets on wire electrode depends on the wire configuration and the polymer solution properties.In this study,the effect of parameters such as the wire dimension,the concentration and the average molecular weight of Nylon 6 on the droplet formation was investigated.It was found that the droplet size was increased with the increase of Nylon 6 concentration as well as with the increase of its molecular weight and the diameter of the wire.The phenomena of Nylon 6 droplet formed from liquid entrainment during the free surface electrospinning was found to be dependent on two dimensionless numbers,Bond and Capillary.The dependence of these two numbers on the Nylon 6 concentration was also generalized in a series of equations.Bond was decreased with the increases of Nylon 6 concentration,meanwhile,capillary was increased.In this study,high performance sound absorption composite materials are made of nanofibers mat with different nonwoven substrate.We did plenty of researches on the effect of nanofiber characteristics,structural characteristics,as well as the arrangements of composite materials on its sound absorption performance.It is found that sound absorption materials with 5 layers of composites made of nanofibers mat with gram weight 10g/m2 which are electrospun from PLA solution with concentration 13% and three-dimentional PET single fibers nonwoven substrate have the most excellent sound absorption performance.Its sound absorption coefficient reaches 0.80 at 1000 Hz noise,and the average sound absorption coefficient of this composite material is 0.86 which is quite satisfied.