Acoustic properties for composite materials based on alfa and wood fibers

Novel sound insulation biocomposite materials have been elaborated using treated alfa fibers and sawdust wood fibers as reinforcing materials, and polyvinyl acetate as a binder agent. Alkaline treatment was applied to alfa fibers to remove the resin from the steams. X-ray diffraction, Scanning electron microscope and Fourier-transform infrared spectroscopy have been performed to ensure the undesirable substances have been removed. The sound absorbing properties have been investigated by the two-microphone impedance tubes of type 4206 B&K test. The recorded data were compared and analysed, especially in medium and high frequencies. The maximum value of the sound absorption coefficient corresponding to spruce and beech wood fibers based composites are 0.98 at 2048–2288 Hz and 0.98 at frequency range respectively. The size of the air gaps thickness and of the additional woven flax shell layer has some significant effects especially for the low frequencies. The results obviously show that the use of the biocomposites based on alfa fibers and wood fibers, for sound absorption applications, represents a smart choice and could be used as an alternative way to conventional materials based on synthetic fibers used for sound absorbing panels.