Preparation of sound-insulating material based
on discarded cow hair
Yiwei Zhang, Benmin Zhang, Zhihua Shan
Key Laboratory of Leather Chemistry and Engineering, Ministry of Education, Sichuan University, Chengdu 610065, China
Correspondence to: Z. Shan (E-mail: firstname.lastname@example.org)
In this article, we report a study on new functional materials based on the structural features of hair. In this study,
discarded cow hair was treated with acid and hydrogen peroxide, dried, and pulverized to obtain a hair powder (HP). A sound-
insulating film (SIF) was prepared via the mixing of HP with acrylic resin [poly(acrylic acid) (PAA)]. On the basis of the function
for the SIF, the formation conditions, including the HP weight percentage, film-forming temperature, and solvent, were investigated.
The sound-insulating properties were studied and compared with commercially available sound-insulating materials. The SIF had an
equivalent sound-insulating power to that of an asphalt-based or a rubber-based board but a better power than that of a polyure-
thane (PU)-foam-based board with identical thicknesses in the 20–20,000 Hz sound wave.
2018 Wiley Periodicals, Inc. J. Appl. Polym.
Sci. 2018, 135, 46332.
applications; composites; films; membranes; resins
Received 7 September 2017; accepted 2 February 2018
Noise from sound waves has different frequencies, intensities, and
phases. The acoustic frequency that the human ear can recognize
is 20–20,000 Hz. When the ambient noise is less than 60 dB,
human beings can work, learn, and so on. At 90 dB, hearing is
damaged, and normal work will be affected.
whose the noise frequency is higher than 90 dB, humans basically
cannot think or talk, and exposure to these frequencies easily
causes various diseases. Usually four sources of environmental
noise make up major sound pollutions today: traffic noise, life
noise, construction noise, and factory noise.
among people has been aroused by noise pollution because it is a
major health concern. Since 1972, INTER-NOISE, which is held
yearly, has explored the research progress on noise in industry.
The reflection, absorption, and transmission of sound waves
occur when a sound wave is incident on a material. Sound insula-
tion can be obtained by the reflection and absorption of sound
waves. The absorption of sound waves is the main method used
to reduce noise.
In various types of materials, most sound-
insulating materials are porous; these include wool insulating
glass fiber materials,
carbon fiber materials,
mer–hollow microsphere composite materials,
France Natpural Co. introduced a natural insulating
material, BATIPLUM, which is mainly composed of processed
duck feathers, wools, and natural fibers. Germany Freudenberg
Co. produced an efficient, nonwoven, sound-absorbing material.
Other materials, such as fly ashes, ceramsites, and cements, can
shorten the echo time and significantly enhance antinoise ability
when these materials are reasonably mixed.
composites can also demonstrate good sound-insulating effects.
With increasing awareness of the environmental impact and
health issues of materials, people are more inclined to use natural
materials to make sound-insulating materials.
Compared to traditional insulation materials, wool is potentially
an excellent sound-insulating material.
There are many advan-
tages to using wool as a sound-insulating material; these include
its environmental sustainability,
lack of negative effects on
ease of use, and good sound-insulating perfor-
Cow hair and wool have similar structural features. It is
possible to use cow hair to make a sound-insulating material. Dis-
carded cow hairs are mainly obtained from tannery unhairing
processes; the discarded cow hairs consist of intact cow hairs and
ones damaged by chemicals. With the increase in environmental
pressure, during unhairing, hair saving has replaced hair destruc-
tion to reduce the number of pollutants in tannery wastewater.
For every 30 kg of salt wet cowhide, approximately 2.5 kg of dis-
carded cow hair remains after unhairing. A medium-size tannery
that processes 2000 raw hides daily will yield 5 tons of discarded
cow hair. The main component of hair is keratin. The thick diam-
eter of discarded cow hair is at least 50 lm, and the fine diameter
is 15–20 lm. Many disulfide bonds make the keratin structure
2018 Wiley Periodicals, Inc.
J. APPL. POLYM. SCI. 2018, DOI: 10.1002/APP.46332
46332 (1 of 12)