Abstract
Recent studies have highlighted an innovative way to produce highly porous materials based on cellulose fibers. These studies have focused on the foam-forming process, where the cellulose fibers and other components are mixed with foam. In the authors’ previous research, the foam-formed cellulose materials (FCM) were obtained by mixing a surfactant with cellulose fibers, taken from virgin pulp and recovered papers. In the present paper, the authors performed additional experimental and computational analyses in order to evaluate the sound insulation capabilities of these FCM beyond the initial impedance of tube investigations. The poroacoustics computational methodology parameters—i.e., airflow resistivity, porosity, tortuosity, viscous, and thermal characteristic lengths—were herein evaluated. This analysis was performed using both a theoretical/empirical approach from the specialized literature and an experimental investigation developed by the authors. The computational investigations were conducted in two stages: First, we evaluated the approximation of the experimentally gained normal incidence parameters, in terms of absorption and reflection, respectively, relative to the estimated ones. The second stage of analysis consists of a parametrical estimation of sound insulation characteristics concerning the incidence angle of sound hitting the porous layer. The results presented in this paper are in agreement with the computational experimental results, providing extended soundproof characteristics to the incidence angle of the acoustic field. Further, this study supplies additional information useful for future analyses regarding the influences of random geometry air inclusions into the FCM layer.
Highlights
Sound absorbing materials with low density are often used for protection and insulation applications
Relative error [%] of experimental value related to Relative error [%] of average value related to Comparing and summarizing the assertions presented in previous sections of this paper, the authors proposed a set of specific characteristics for the formed cellulose materials (FCM) in order to perform the computational analyses
The cellulose loose-fill composite materials obtained by the aforementioned foam-forming methods represent an alternative solution for soundproof, especially compared with applications obtained using conventional methods
Summary
Sound absorbing materials with low density (e.g., polystyrene foam) are often used for protection and insulation applications. Bio-based alternatives for low-density insulation materials are needed to replace the fossil-based ones [1]. The development of biomaterials based on highly recyclable and biodegradable lignocellulosic fibers have attracted great interest in the composite material science community as a viable alternative to petroleum-based materials [2,3]. Besides their biological process control on waste management, these materials have many important applications in the fields of sound and energy absorption, thermal insulation, radiation shielding, filtration, packaging, building industry, electronics, and medicine. Porous materials have a high sound absorption coefficient compared to other materials [4]
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