Moisture-proof And Ultra-fine Electrospun Fibrous Sponges For Effective Sound Absorption

With the continuous development of society,the problem of noise pollution is more and more serious.It has become an important factor affecting human’s normal study and life.Low decibel noise will make people agitated,difficult to fall asleep,high decibel noise will make people unbearable,and even may cause death,there is a serious threat to human physical and mental health,in addition,noise may destroy the ecological environment,cause economic losses,therefore,research and development of excellent performance of sound absorbing materials is imperative.Among many sound-absorbing materials,fibrous sound-absorbing materials have broad application prospects in the field of sound-absorbing and noise-reducing due to their mature preparation technology,inexpensive and excellent sound-absorbing performance.Refining fiber is an important way to improve the sound-absorbing properties of fibrous materials.Among many refining fibrous methods,electrospinning has unique advantages and can stably prepare ultrafine fibrous materials with excellent properties.Through the construction of three-dimensional fluffy structure of electrospinning fibrous materials,the bulk density of materials can be effectively reduced,and the porosity of materials can be improved,so as to increase the path of sound energy dissipation and greatly improve the sound-absorbing performance of materials.In addition,sound-absorbing materials need to have certain moisture-proof function to meet the application in high humidity environment or plum rain weather.Therefore,it is of great significance to develop ultrafine fibrous materials with stable three-dimensional fluffy structure by electrospinning technology.Firstly,the study uses polymethyl methacrylate(PMMA)as raw material to prepare PMMA ultrafine fibrous materials with different polymer concentrations.The influence of polymer concentration on ultrafine fibrous materials is explored.The experimental results show that when the polymer concentration is 26wt%,the prepared PMMA ultrafine fibrous materials have three-dimensional fluffy structure.The fiber diameter is small and the diameter distribution is uniform.Then,the mechanical properties of polyurethane(PU)reinforced materials were introduced to investigate the effect of PMMA/PU ratio on the morphology and structure of the fibers.The experimental results showed that the average diameter of the fluffy fibrous sponge prepared by PMMA/PU ratio of 4/1 was 1.9μm,and the porosity could reach99.2%.The bulk density of PMMA/PU ultrafine fibrous sponge is only 9.8mg/cm~3,which also has excellent mechanical properties and sound absorption.In addition,fluorinated polyurethane(FPU)was introduced to enhance the moisture resistance of the material,and the effect of the content of FPU on the morphology and moisture resistance of the fibrous sponge was investigated The results showed that the content of FPU in polymer had little effect on the morphology and structure of PMMA/PU/FPU ultrafine fibrous sponge,and when the content of FPU in polymer was 10wt%,The static water contact angle of the sponge reaches 138°,and the moisture absorption rate is 1.4%,which shows it has excellent moisture-proof performance.The mechanical properties and sound-absorbing properties of ultrafine fibrous sponge were further studied.The results showed that PMMA/PU/FPU ultrafine fibrous sponge has good mechanical properties under 5%,10%and 15%tensile strain and 20%,40%,60%and 80%compressive strain,and almost no plastic deformation after 100 compression and tensile cycles tests.It shows excellent structural stability and compression tensile recovery performance,and when the thickness of the sponge reaches30mm,the noise reduction coefficient of the sponge can reach 0.5,showing excellent sound-absorbing performance.Finally,this study compared PMMA/PU/FPU ultrafine fibrous sponge with polyethylene terephthalate/polypropylene(PET/PP)two-component sound-absorbing sponge,polyester fibrous(PET)sound-absorbing board and polyurethane sound-absorbing sponge.The experimental results show that PMMA/PU/FPU ultrafine fibrous sponge has the largest specific surface area.The average fiber diameter and aperture are smaller than those of the three commercially available sound-absorbing materials.At the same time,ultrafine fibrous sponge has the advantages of large static water contact angle,small moisture absorption rate,short desorption time,and the best moisture-proof performance.The noise reduction coefficient of ultrafine fibrous sponge is greater than 0.5,showing excellent low-frequency and high-frequency sound absorption performance.Moreover,ultrafine fibrous sponge is an ideal sound-absorbing material due to its ultra-light characteristics.The controllable preparation of PMMA/PU/FPU ultrafine fibrous sponge provides a new idea for the design of moisture-proof and fibrous materials for sound absorption and has far-reaching significance.