Pure polyurethane foam and nanocomposite foam are used to absorb sound. In this study, hollow silica nanospheres and rigid silica nanoparticles were added to the polyurethane matrix and their sound absorption properties were investigated by impedance tube and compared with pure polyurethane foam. Reinforcement phase influences on the morphology of the matrix were studied by scanning electron microscopy. Due to greater effects of the rigid silica nanoparticles on the morphology of the matrix, it was expected to increase the sound absorption coefficient of the rigid silica nanoparticles/polyurethane, more than hollow silica nanospheres/polyurethane, but the results show that the hollow silica nanospheres increased absorption coefficient of the composite more efficiently. The crust of hollow silica nanospheres increases the number of boundaries in a sound wave, and the air gap inside them cause the sound wave to damp. So the intrinsic property of the hollow silica nanospheres is more effective than the matrix morphology. Thus, by the same content of reinforcement in the matrix, hollow silica nanosphere/polyurethane sample with sound absorption coefficient of 0.87 for a thickness of 9 cm has the highest sound absorption coefficient compared to the rigid silica nanoparticles/polyurethane sample and pure polyurethane foam. In pure and nanocomposite samples, sound absorption coefficient increased by increasing the thickness of samples.

中文翻译：

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空心二氧化硅纳米球和硬质二氧化硅纳米粒子对柔性聚氨酯泡沫纳米复合材料声波吸收的作用

纯聚氨酯泡沫和纳米复合泡沫用于吸音。在本研究中，将空心二氧化硅纳米球和硬质二氧化硅纳米粒子加入到聚氨酯基体中，通过阻抗管研究它们的吸声性能，并与纯聚氨酯泡沫进行比较。通过扫描电子显微镜研究了增强相对基体形貌的影响。由于刚性二氧化硅纳米粒子对基体形貌的影响更大，预计刚性二氧化硅纳米粒子/聚氨酯的吸声系数会比空心二氧化硅纳米球/聚氨酯增加，但结果表明，空心二氧化硅纳米球提高复合材料的吸收系数更有效。空心二氧化硅纳米球的外壳增加了声波中的边界数量，其中的气隙使声波衰减。因此，空心二氧化硅纳米球的固有特性比基体形态更有效。因此，在基体中相同的增强剂含量下，与硬质二氧化硅纳米粒子/聚氨酯样品和纯聚氨酯泡沫相比，9 cm 厚度的吸声系数为 0.87 的空心二氧化硅纳米球/聚氨酯样品具有最高的吸声系数。在纯样品和纳米复合样品中，吸声系数随着样品厚度的增加而增加。在基体中相同的增强剂含量下，与硬质二氧化硅纳米粒子/聚氨酯样品和纯聚氨酯泡沫相比，9 cm 厚度的吸声系数为 0.87 的空心二氧化硅纳米球/聚氨酯样品具有最高的吸声系数。在纯样品和纳米复合样品中，吸声系数随着样品厚度的增加而增加。在基体中相同的增强剂含量下，与硬质二氧化硅纳米粒子/聚氨酯样品和纯聚氨酯泡沫相比，9 cm 厚度的吸声系数为 0.87 的空心二氧化硅纳米球/聚氨酯样品具有最高的吸声系数。在纯样品和纳米复合样品中，吸声系数随着样品厚度的增加而增加。