The Preparation Of Polyurethane Foaming Materials And Optimization Of Sound Absorption Structure

With the process of our society,noise pollution becomes more and more serious.It affects a lot of aspects of people’s life, underwater acoustics is an important branch of modern acoustics,the main method of controling noise is to use the sound absorption materials.The main research objects of this paper is polyurethane(PU),its viscoelasticity and impedance matching with the sea can make PU dissipate more acoustic energy. We want to achieve the purpose of deadening the noise of anechoic tank and other underwater acoustic platform by optimize the acoustic absorption performance of acoustic absorbing material used inside.This paper focus on the synthesis technology and structure design of PU to obtain acoustic absorption material with high acoustic absorption performance.We synthetize polyether-polyol type PU foams by quasi-prepolymer method. A number of PU foam materials with different process parameters is synthetized according to different factors that may affect underwater sound-absorbing performance.The optimum temperature and raw material is obtained through initial experiment.Baesd on that,we study the influence of addition amount of foaming agent(H2O) on acoustic absorption performance of PU, FTIR、 SEM、DSC、DMA analysis techniques are used to analyze the samples. FTIR is used for structure characterization while SEM is for morphology analysis. We study dynamic mechanical property and thermal behavior of different PU specimen,obtaining their characteristic temperature and damping property. Pulse tube method goes for the measurement of sound absorption coefficient.Then we conclude the best process parameters through absorbent capability measurement as well as mechanical property.After that,the paper explores and optimize the structure of PU underwater sound absorption materials,a PU foam model with A-shape structure and cavity is built.Then MATLAB programming calculation is used to obtain the sound absorption coefficient in different cases, bringing into relative parameters.The structure dimension and parameters of A-shape are settled through numerical simulation.Simulation shows that elastic modulus、the shape and size of cavity as well as the vertex angle have a great influence on the property of underwater sound absorption materials,while the density of the material make little sense.Less elastic modulus can improve sound absorption coefficient in low frequency band;30 degree is the best angle for absorption;the existence of cavity can improve the sound absorption property,and the shape of cavity is an important factor, exponential type is better than cylindrical as well as round table type.What’s more,the sound absorption property of A-shape structure almost unchanges under 5MPa hydrostatic pressure.Eventually, the best acoustic absorption performance of A-shape underwater sound absorption materials is obtained theoretically.The optimized PU sample reach our goal in sound absorption coefficient. A-shape structure is obviously superior to the cylinder in acoustic performance,the conclusion reached in this paper can lay solid foundation for the universal application of polyurethane acoustic absorbing material in more areas.