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.