We investigated the use of seaweed-derived agar-based composite films as sound absorbers. Nonporous and porous films of varying concentrations of agar (1% to 5% w/v) and their composite films with glycerol (5% w/w) as the plasticizer and nanocrystalline cellulose (2% to 10% w/w) as the reinforcement material were fabricated. Porous films, of about 80% porosity, were obtained by a freeze-drying technique and nonporous films by drying in a hot air oven. Scanning electron microscopy study showed that porous films had interconnected walls with a pore size of 10 μm. Measured acoustic absorption coefficients using the two-microphone transfer function method revealed that the porous films were effective in sound absorption. The films of 5% w/v agar concentration had the highest sound absorption. The addition of glycerol enhanced sound absorption, due to the damping nature induced by it, whereas the addition of nanocrystalline cellulose to the glycerol-added films did not alter its acoustic properties.

中文翻译：

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琼脂基复合膜作为有效的可生物降解吸声器

我们研究了使用海藻衍生的琼脂基复合薄膜作为吸音材料。不同浓度琼脂（1% 至 5% w/v）的无孔和多孔薄膜及其复合薄膜，其中甘油（5% w/w）作为增塑剂，纳米晶纤维素（2% 至 10% w/w）作为增塑剂制作了加固材料。通过冷冻干燥技术获得孔隙率约为 80% 的多孔薄膜，通过在热空气烘箱中干燥获得无孔薄膜。扫描电子显微镜研究表明，多孔薄膜具有相互连接的壁，孔径为 10 μm。使用双麦克风传递函数方法测量的吸声系数表明，多孔薄膜在吸声方面是有效的。5% w/v 琼脂浓度的薄膜具有最高的吸声性。添加甘油增强了吸音效果，