Sound Absorption Properties Of Polyurethane Foam And Polyproylene Fiber

With the development of industries, transportation and construction, noise pollution has been one of the four pollutions. The most basic means of controlling noise is the sound absorption material. Polyurethane foam (polyurethane foam, PU) is a typical porous acoustic material, which combines the material properties of the polymer and the damping function of a flexible material, is a good sound-absorbing material. So it is significant to study sound absorption property of PU foam material.In this article, we studied the effects of surface agent and catalyst on pore diameter and distribution in the PU foam’s synthesis, and especially on sound absorption properties of PU foam. The results demonstrate that the contents of surface agent and catalyst have great influence on pore diameter, distribution and sound absorption property. In the synthesized system of PU foam in this article, when the contents of silicon, DABCO and DBTDL are2wt%,0.3wt%,0.4wt%respectively, the average sound absorption coefficient of PU foam is0.54, which showed a better sound absorption property and pore scatter uniformity.We also studied the effects of thickness, cavity thickness, temperature of raw material on pore structure and sound absorption property. We found that with the increase of thickness and cavity thickness, sound absorption property of PU foam is improved, the degree of increase is limited. The results also showed that the temperature of raw material has great influence on it. When the temperature is45℃, there are many closed pores and half open pores appeared, which showed the best sound absorption property.PU foam has good sound absorption property in high frequency, while the medium-low frequency is not so good, so we studied how to enhance the sound absorption property in medium-low frequency. Firstly, we studied the sound absorption property of polypropylene (PP) fiber.We investigated the effects of length, density and thickness of PP fiber on sound absorption property. The results show that the length of PP fiber has no influence on sound absorption property, while with the increase of density and thickness of samples, the sound absorption property is improved, and showed better property in medium-low frequency. We discussed the double structure composite of PP layer and PU layer, and found that this manner can enhance the sound absorption property and got a high absorption coefficient in medium-low frequency. The configuration of the PP-PU double-layer structure has a profound impact on its sound absorption property, and the layer which faced the sound source has the dominant function to sound absorption properties.We synthesized PU foam with PP fiber together. The results showed that both pore structure and sound absorption property were changed when the PP fibers exist. When the content of PP fiber is0.5g, the PP-PU showed the best sound absorption property.