Preparation And Acoustic Properties Of The Layered Graphene/Styrene-acrylonitrile Copolymer/Polyurethane Composites

With the increasing degree of industrialization,noise pollution interferes with normal human work and life,as a common form of environmental pollution.Noise also induces cardiovascular diseases such as hypertension and myocardial infarction.In order to reduce the harm of noise pollution,it is found that the polymer materials have the characteristics of good viscoelasticity,high damping,easy processing and light weight.By adding high-performance filler or optimizing its structure,the acoustic material with good vibration and noise reduction performance can be obtained.In this paper,the foamed polyurethane composites(soft layer sound absorbing materials)containing various additives were firstly prepared.And the high-strength fillers graphene oxide(GO)and ethylenediamine modified graphene oxide(GO-EDA)were combined with styrene-acrylonitrile copolymer(SAN)to prepare SAN-based nanocomposites(hard layer sound insulation materials).Finally,the soft layer sound absorbing materials and the hard layer sound insulating materials were layered and compounded,and the influence of structural composition on the sound insulation performance of the layered composites were studied.The specific research contents are as follows:(1)The foamed polyurethane composites with different mass fraction of foaming agent,wood fiber,bamboo fiber and plasticizer were prepared by hot pressing foaming method and thermoplastic polyurethane material(TPU)as matrix.Scanning electron microscopy(SEM)revealed that the foamed polyurethane composites had abundant pore structures such as closed pores,semi-open pores and open pores,which is beneficial to improve the sound absorption performance of the materials.Dynamic mechanical property test(DMA)indicated that the addition of foaming agent and fiber fillers adversely affected the damping properties of the foamed polyurethane composites.The damping properties of foamed polyurethane composites increased with the increase of plasticizer content.The foamed polyurethane material with the plasticizer content of 30% had a loss factor of 50.0% higher than that of pure foamed polyurethane material.Sound absorption test showed that the sound absorption effect of the foamed polyurethane composites was improved by foaming agent,fiber fillers and the plasticizer.Among them,the foamed polyurethane composite with bamboo fiber content of 2.0%,plasticizer content of 30% and foaming agent content of 1.5% had better damping property and sound absorption performance.The loss factor and average sound absorption coefficient compared with pure foamed polyurethane materials were increased by 37.5% and 24.1%,respectively.(2)GO was prepared by the modified Hummers method,and GO-EDA was obtained by modification with ethylenediamine.The GO and GO-EDA were tested by infrared spectroscopy and thermogravimetric analysis.It was found that there are abundant oxygen-containing functional groups on the surface of GO.The surface of GO-EDA had nitrogen-containing groups,and the thermal stability was obviously improved compared with GO.GO and GO-EDA were combined with SAN by solution blending and melt blending to obtain SAN-based nanocomposites with different filler mass fractions.SEM showed that GO and GO-EDA were dispersed well in the SAN matrix.The areal density and DMA test showed that the areal density and storage modulus of each component of SAN-based nanocomposites increased with the increase of filler content.The maximum storage modulus increased by 32.8% compared with pure SAN.The result of sound insulation test showed that the SAN-based nanocomposite conformed to the sound insulation law of a single-layer homogeneous plate.Among them,2.0%GO-EDA/SAN nanocomposites had the best sound insulation performance,and the value of the average sound insulation was 17.4% higher than that of pure SAN.(3)The layered composite materials with double-layer and three-layer structure were prepared by laminating hot pressing of soft layer polyurethane foamed materials and hard layer SAN-based nanocomposites.Sound insulation test showed that the double-layer composite materials had the better sound insulation performance when the hard layer materials faced the sound source,and the value of average sound insulation was increased by 25.3% compared with the single layer pure SAN.DMA test showed that the damping temperature range of the doubled-layer composites was widened.When the soft layer sound absorbing materials were the intermediate damping layer and the hard layer sound insulation materials outer were constrained layer,the three-layer constrained damping structure material had better sound insulation effect.The average sound insulation of the three-layer constrained damping structure material with the 2.0%GO-EDA/SAN nanocomposite on the outer layer was 42.25 d B,which was 33.8% higher than pure SAN single layer.Compared with double-layer composite structure materials,the sound waves in the three-layer composite material with constrained layer/damping layer/constrained layer structure were consumed more energy by reflection and vibration damping,which had better sound insulation and noise reduction effects.