Sound absorption and thermal insulation performance of sustainable fruit stone panels

Abstract

The sound absorption and thermal insulation behavior of panels made of different fruit stones, including peach, apricot, plum, date, and black cherry, were investigated. To this end, samples in the crushed and uncrushed forms were fabricated with thicknesses of 30 and 50 mm. The FE-SEM (Field Emission Scanning Electron Microscopy) and Atomic Force Microscopy (AFM) images showed that the studied stones have different morphological and topological surfaces, which in turn lead to different sound absorption coefficients (SACs) and effective thermal conductivities (Keff). It was found that smaller fruit stones with higher surface roughness generally have higher noise reduction coefficients, and this was more pronounced for samples of 50 mm thickness. In addition, samples in the crushed form enjoyed superior sound absorption performance compared with their uncrushed counterparts. The SAC peak in the crushed form appeared at lower frequencies and its value was higher than that of the uncrushed stones. Moreover, when the air gap was introduced, all samples showed excellent sound absorption at frequencies of 400–600 Hz. It was found that, while an increase in sample thickness led to an enhancement in SAC at low and middle frequencies, the Keff values did not significantly change. Uncrushed samples demonstrated enhanced thermal insulation properties compared to their crushed counterparts. The Keff values of the specimens were found to be in the range of 0.087–0.204 W.m−1 K−1, indicating the good thermal insulation performance of the panels. The frequency-dependent SACs of fruit stone panels were predicted using the Johnson-Champox-Allard and Attenborough models, and acceptable consistency was observed.