A comparative study on the acoustic absorption properties of green synthesis cellulose nano enset fibers

Abstract

Natural fibers are becoming a valid alternative to most commercially used synthetic fibers in sound absorbing materials. In recent years, natural fibers have been considered as valid raw materials for producing ecofriendly sound absorbing materials at low cost. This paper presents a new study on enset nanofiber sound absorbing material which was prepared by enzyme treatment and mechanical hammering of the surface of enset woven fabric. Enset nano fiber (ENF) was fabricated by defibrillation of underutilized abundant byproduct fibers from the surface of enset woven fabrics into micro and nano-scale fibers by alpha-amylase enzyme treatment and then mechanical hammering. The purpose of this approach is that the product will be economic and environmentally friendly and also consumption of eco-friendly products is a serious concern of researchers and policymakers. The study was conducted by using impedance tube method and the sound absorption properties of enset micro and nanofibers in a frequency range of 1000 to 6000 Hz were studied by changing the diameter, thickness and percentage of enzyme concentration during fiber treatments. Parameters for enset nanofibers were: number of board layers (single, double, triple and fourth-layer having sample thickness of 10-13 mm), fine fiber size (micro and nano meter), and fine fiber treatments content (10, 15 and 20% w/v), pressing time (10 min), board density (0.95 g/cm3), press pressure (40 kg/m2) and press temperature (180 degrees C) were held constant. The experimental results revealed that at the same frequency (4500 Hz), the sound absorption coefficient value was improved by 176 and 213% when neat enset fabric was treated and hammered with 10 and 20 w/v % concentration of amylase enzymatic respectively. The maximum sound absorption of neat enset fabric and enset nanofibers was recorded as 0.47 and 0.99 around 5351 Hz respectively. These results indicate that the acoustic property of enset fiber was improved by 47% when neat enset fiber was converted into green enset nanofiber forms by enzyme treatment and mechanical hammering. The experimental results shown that green synthesis of fine fibers from the surface of woven fabric improved the maximum acoustic peak values by 43% (microscale) and 59% (nanofiber) compared with macroscale enset fibers. These simple and cost effective green cellulosic enset nanofiber formations would have a promising result for small scale acoustic enterprises.