Foam-formed cellulose composite materials with potential applications in sound insulation

Abstract

Use of foam-formed cellulose composite materials is a viable alternative that provides potential savings in terms of raw materials, energy and water compared with conventional methods for obtaining the fibrous composites. This new innovative manufacturing method leads to obtaining porous materials with low density and low environmental impact, which could replace the petroleum-based products in different industrial application fields like sound control. In this paper is presented a methodology for producing low-density cellulose composite materials in foam media. In this methodology a surfactant is mixed with cellulose fibres (from virgin pulp and recovered papers) at high shear velocity (2000 r/min) to entrain air, dewatered on Buchner funnel under low vacuum and air dried in non-restrained conditions. The obtained composite materials have been tested by sound insulation parameters (sound transmission loss and absorption coefficients) using two experimental impedance tubes with four-microphone configuration and anechoic termination. Three samples of foam-formed cellulose composites and one water-formed composite sample were obtained. Their sound insulation performances were compared with two different commercially available petroleum-based materials currently used in sound insulation applications (i.e. expanded/extruded polystyrene). The experimental results show comparable performances between foam-formed cellulose composites and polystyrene-based samples, but in terms of the environmental impact, these materials can be an appropriate green alternative which can cut the costs of recycling process.

Computational Investigations on Soundproof Applications of Foam-Formed Cellulose Materials

“…Each set of tests corresponded with large and small diameter tubes. These results were presented in detail [36] and had specifications within ISO 10534-2:1998 (acoustics, determination of sound absorption coefficient and impedance in impedance tubes, Part 2: Transfer-function method). In addition, the computational estimations were conducted with respect to the empirical models: D-B, JCA, and JCAPL (briefly presented in Section 2.3.3).…”

“…The filtering was developed at a low level and vacuumed for approximately 20 min. Dewatered FCM with wet structure is presented in Figure 1 [36].…”

“…Snapshots of wet structures for the foam-formed cellulose materials within this study: ( a ) sample P1; ( b ) sample P3S; and ( c ) sample P4. [36]. …”

“…For soundproof applications, the use of recyclable cellulose loose-fill composite materials represents an alternative solution to conventional methods for obtaining the fibrous composites. Many researchers have showed how acoustic measurements have excellent sound insulation performance on materials such as recycled cellulose fibers (i.e., luffa, yarn waste, coconut, and Kenaf fiber) [31,32,33,34,35,36]. The sound absorption coefficients of flax fiber fabric and its reinforced composite (i.e., balsa wood) were predicted by Zhang and Shen [37] using a double-porosity model, which showed a superior sound absorption performance (especially at high frequency) compared to the synthetic materials-based sandwich structure composite that contributed to their multi-scale structures of sound wave attenuation and energy dissipation.…”

“…In our study, foam-formed cellulose materials (FCM) were obtained by mixing a surfactant with cellulose fibers and then tested with promising results on sound absorption applications [36]. Other than the basic acoustical investigations, we performed an additional experimental and computational analyses in order to evaluate the sound insulation capabilities of these bio-based materials.…”