The invention provides lightweight sound-absorbing mute cotton and a preparation method thereof, the lightweight sound-absorbing mute cotton is of a bionic gradient structure and is divided into three
layers, the bottom layer dissipates high-
frequency sound waves, the middle layer optimizes intermediate-frequency
resonance, and the upper layer enhances low-
frequency sound wave scattering. The preparation method comprises the following steps: respectively preparing bottom-layer
slurry, middle-layer
slurry and upper-layer
slurry; pre-cooling the bottom of a mold, and carrying out synchronous three-layer co-injection molding on the three kinds of slurry: carrying out one-way freezing to form a longitudinal gradient aperture; freezing and
drying to obtain a three-layer gradient structure material; immersing in a
graphene oxide quantum dot
ethanol solution for vacuum treatment; heating, adding
ascorbic acid, keeping for 2 hours, and applying 0.5% pre-strain to the material; photo-
thermal curing is performed; and performing hot-pressing shaping to obtain the product. The gradient structure design is adopted, and the aperture, the
fiber distribution and the filler type are regulated and controlled, so that
acoustic impedance gradient change is realized,
sound wave reflection is reduced, and the sound
absorption efficiency is improved.