Research On Sound Absorption And Insulation Properties Of Multilayer Structural Material Based On Discarded Polyester Fiber

With the developing of economy and industrialization, noise pollution became the third pollution following air pollution and water pollution. Noise produces many harmful effects to human nervous system, such as sleeplessness, exhaustion and hypomnesis. Polyester fiber is one of chemical fiber, which has the largest production and consumption in the world. Waste polyester products get more and more people’s attention, as they are difficult to degrade and pollute the environmental. So, it is important to select a correct method to treat waste polyester fiber. To solve the problems above, this paper using waste polyester fibers and fabrics, to develop a multi-layered composite structure sound absorption materials. Sound absorption properties of the materials were investigated, and the theoretical model of sound absorption coefficient and sound insulation established.In this paper, firstly, polyester fiber/TPU composite material was prepared by blending hot pressing method, using polyester fiber as reinforcing material, thermoplastic polyurethane as matrix material. The effect of fiber content, fiber length and pressure on mechanical properties of composite was analyzed through orthogonal experiments, and the optimal process conditions were achieved. When polyester fiber length of 15 mm, polyester fiber concentration of 35%, pressure of 5 MPa, the composite material with the best mechanical properties, its tensile strength is 51.26 MPa, tensile modulus is 0.45 GPa, the bending strength is 49.56 MPa, the bending modulus is 0.85 GPa, the impact strength is 35.71 KJ/m2.Then, the composite was processed into perforated plate and combined with polyester fabric and achieved sound absorbing material. The effect of perforate plate aperture, perforate plate thickness, perforation rate and polyester fabric on sound absorbing properties was investigated. Found that, the perforated plate aperture affected sound-absorbing composite’s absorption coefficient peak; perforate plate thickness, perforation rate and polyester fabric layers affected the composite’s sound-absorbing frequency range. Using sound absorbing material with different structure parameters constituted a three layers structure of sound absorbing material. The combination method and the change of the absorption coefficient peak position of the three layers structure of sound absorbing material were studied. Found that, combination method has a great influence on the sound absorption performance of the material. The right combination method could make sound absorption band of material to be broadened and sound absorption performance of the material to be improved.The laminated plate with good sound insulation performance was prepared by waste polyester fabric with chlorinated polyethylene. The sound insulation performance of laminated plate, which achieved by changing the number of polyester fabric layers, hot density and pressure was tested. Found that, increases the polyester fabric layers, density and pressure are conducive to improve the sound insulation performance. When contained four layers of polyester fabric, the density of the material is 0.7g/cm2, the thickness of the material is 6mm, the average sound insulation quantity of the laminated plate is 30.64 dB.The sound absorption coefficient of composite structure materials and sound insulation quantity of laminated composite plate has been calculated according to the theoretical model. By contrast of theoretical calculation value and actual measurement value found that, the theoretical calculation values have good match with the actual measured value.Finally, a multi-layer structure of composite with sound absorption and sound insulation properties was achieved by the combination of three layer sound absorption material and sound insulation composite. Its absorption coefficient and sound insulation quantity was tested, and the sound absorption coefficient is 0.55, the average amount of sound insulation is 33.67 dB. After flame retardant treatment, materials have flame retardant function and the limiting oxygen index was more than 27%. By thermal conductivity test, found that, the thermal conductivity is less than 0.2 W/mK. The materials also have thermal insulation performance.