废弃玉米秸秆的结构特征及其吸声性能

为增加废弃玉米秸秆的回收利用率,分别以长度为1.5、6和10 mm的废弃秸秆颗粒、棉纤维和大麻纤维为增强材料,聚己内酯为基体材料,通过热压成型工艺制备厚度为1.5 cm的吸声复合材料。采用声阻抗传递函数法对复合材料的吸声性能进行测试与对比,并分析其吸声机制。结果表明:1.5 mm长的废弃秸秆所制备复合材料的吸声性能最好,最大吸声系数达到0.71,平均吸声系数为0.50,降噪系数达到了0.51;废弃秸秆纤维素大分子主链上的氧六环结构为声波反复反射、折射提供了基础,较高的线性使得氢键等单键能够自由旋转,增加了声波能量的消耗,且废弃玉米秸秆的结晶度低使得声能易于沿着分子链传播,从而将声能转化为分子链段振动耗散。

Structural characteristics and sound absorption performance of waste corn straw

In order to recycle effectively the waste corn straw, sound-absorbing composites with a thickness of 1.5 cm were prepared by hot pressing the waste straw pellets with length of 1.5 mm, 6 mm, and 10 mm, cotton fiber and hemp fiber as reinforcement materials, and polycaprolactone as the matrix material. The sound absorption capabilities of the composites were evaluated and compared using the acoustic impedance transfer function approach. The results demonstrate that the 1.5 mm length of waste corn straw is suitable for the creation of sound-absorbing composites because it has the best sound absorption performance, with a maximum absorption coefficient of 0.71, an average absorption coefficient of 0.50, and a noise reduction coefficient of 0.51. The oxyhexacyclic structure on the main chain in corn straw cellulose macromolecule provides the basis for repeated reflection and refraction of sound waves. The high linearity enables the hydrogen bonds and other single bonds to rotate freely, which increases the consumption of sound energy. Moreover, the low crystallinity of waste corn straw makes the sound energy easy to propagate along the molecular chain, thus converting the sound energy into the vibration dissipation of the molecular chain.