The advent of composite materials has made it possible to use waste from production processes that, combined with materials of renewable origin, contribute to products with low environmental impact. Applying waste from non-renewable sources such as rubber in new products can have a lower environmental impact, as long as there is no need for chemical modifications for its reuse. The challenge of wood-based particulate composites lies in the internal interaction/adhesion of different materials when joined together and in the properties that can be obtained when considering wood, with pores in its microstructure, and rubber, known for its ability to absorb and dissipate vibrations. Characteristics of both materials are required for acoustic applications. This work aims to produce and characterize particleboards and castor oil–based polyurethane foam for thermoacoustic compositions. Particleboards were produced with Pinus sp. wood (W) waste treated with CCB (a basic preservative of chromium, copper, and boron oxide), tire rubber (R) wastes (100%W+50%R and 100%W+75%R), and denoting wood:rubber inputs of approximately 70:30 and 60:40), and castor oil–based polyurethane adhesive, in different configurations in terms of thickness (10 and 20 mm) and pressure (2.5 and 4 MPa) in the manufacturing press. Castor oil and commercial polyurethane (PU) foams were also produced for acoustic tests. The results show that panels containing only wood had low density (560 kg/m3) while panels containing rubber had medium to high density (810–940 kg/m3). Wood panels showed a higher porosity (55.7%) compared to wood-rubber panels (37.3%), being related to the density and press pressure, but also to the porous and fibrous nature of the wood compared to the more compact rubber. Regarding acoustic absorption, panels containing only wood and pressing pressure resulted in higher sound absorption coefficients (αS) at all frequencies from 100 to 3,200 Hz, with αS=0.84 at 3,200 Hz. The PU foam layer also improved acoustic absorption at specific frequencies, such as αS=0.65 (100%W + 50%R panel) and αS=0.85 (100%W panel) at 1,600 Hz, presenting values close to commercial acoustic materials. This study demonstrated the possibility of using waste to obtain acoustic panels with technical performance and eco-efficiency.
Reis et al. (Sat,) studied this question.