توصيفگر ها :
ضريب جذب صوت , ضريب حرارتي هدايت وپژه , ضايعات ماسك , روش سطح پاسخ , پنل ساختماني پايدار
چكيده انگليسي :
Industrial development and technological advancements in industries and urban areas, in addition to uncontrolled population growth, have brought along a wide range of environmental issues such as noise pollution, greenhouse gas emissions, and municipal and industrial waste production. Noise pollution is the second most threatening environmental factor to human health worldwide, after air pollution. Exposure to harmful noise levels not only results in hearing loss but also leads to various physiological changes such as increased risk of heart attacks and stress. On the other hand, the emissions of greenhouse gases resulting from the use of fossil fuels are a major contributor to global warming and climate change. The use of fibrous porous materials as sound absorbers and thermal insulators is one of the most common methods for reducing noise pollution and energy consumption in buildings. On the other hand, the use of single-use masks during the COVID-19 pandemic has significantly increased. The disposal of these masks in nature has become a serious environmental problem. The disposal of these masks in nature has become a serious environmental problem. The aim of this study is to design, fabricate, and optimize panels made from waste disposable masks, with the application of sound absorption and thermal insulation. For this purpose, the waste masks were transformed into a fibrous mass form using a garnet machine. The resulting fibers, after being mixed with a binder, were molded according to an experimental design based on the RSM-CCD with five different thicknesses (10, 15, 20, 25, and 30 mm), densities (100, 150, 200, 250, and 300 kg/m3), and various percentages of meltblown and spun-bond blend (0, 25, 50, 75, and 100 %). The sound absorption coefficient and thermal conductivity of the panels were examined using the two-microphone impedance tube and the guarded-hot-plate methods, respectively. The sound absorption average (SAA) and effective thermal conductivity (Keff) of the panels were calculated within the range of 0.27-0.49 and 0.031-0.056 W/mK, respectively. The results showed that with an increase in thickness and density of the panels, the sound absorption coefficient increased at low and medium frequencies, with maximum absorption occurring at lower frequencies. However, excessive thickness and density led to a decrease in sound absorption coefficient at higher frequencies. It was found that thickness and density parameters had a positive and negative effect on the SAA, respectively. In the examination of the simultaneous effect of density and blending ratio, it was observed that in order to achieve maximum SAA, the lowest values of density and percentage of meltblown should be chosen. For all thicknesses, Keff significantly increased with an increase in panel density, while an increase in panel thickness had a negligible effect on Keff. Furthermore, it was observed that an increase in the percentage of meltblown ratio has a negative effect on the Keff value of the panel. Based on the based on the p-value, lack of fit p-value, and reasonable agreement between the adjusted R² and the residual sum of squares, the cubic and 2FI models were proposed to predict the values of SAA and Keff, respectively. The optimal conditions were determined to achieve the maximum SAA and minimum Keff in a thickness of 25 mm, a density of 150 kg/m3, and a blending percentage of 25% meltblown. In these conditions, the predicted values of SAA and Keff were 0.47 and 0.032 W/mK, respectively. Finally, three fibrous panels were manufactured under the optimal conditions, and their acoustic and thermal properties were measured. It was observed that there is an excellent agreement between the model results and the experimental results with a 95% confidence level.
