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17 pages, 6537 KiB

Open AccessEditor’s ChoiceArticle

Development of Acoustic Insulating Carpets from Milkweed Fibers Using Air-Laid Spike Process

by Deborah Lupescu, Mathieu Robert and Said Elkoun

Fibers 2025, 13(1), 4; https://doi.org/10.3390/fib13010004 - 7 Jan 2025

Cited by 1 | Viewed by 1221

Fibers from milkweed, which grows in Quebec (Canada), offer a distinct and outstanding advantage compared to other natural fibers: their ultra-lightweight hollow structure provides excellent acoustic and thermal insulation properties for the automobile industry. To highlight the properties of milkweed fibers and reduce the use of synthetic materials in vehicles, nonwoven carpeting made from a blend of milkweed fibers and polylactic acid (PLA) fibers was produced using the air-laid process. Some of the nonwovens were compressed to investigate the effects of increased mass per unit area on their thermal, acoustic, and mechanical properties. The nonwovens’ mass per unit area, thermal insulation, sound absorption coefficient, airflow resistivity, compression, and resistance to moisture were evaluated and compared to other carpets made of natural and synthetic fibers. The findings indicate that milkweed and PLA carpets have lower thermal conductivity values of 37.45 (mW/m·K), (mW/m·K) less than carpets made from cotton and polypropylene. At low frequencies, none of the carpets absorbed sound. At high frequencies, milkweed and PLA carpets showed sound absorption values of at least 0.6, which provide better acoustic insulation than nonwoven materials made from jute and polyethylene (PE) fibers. Milkweed and PLA carpets exhibited better compression values than polypropylene (PP) carpets. Full article

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21 pages, 5947 KiB

Open AccessArticle

Analysis and Optimization of the Noise Reduction Performance of Sound-Absorbing Materials in Complex Environments

by Mengting Mao, Fayuan Wu, Sheng Hu, Xiaomin Dai, Qiang He, Jinhui Tang and Xian Hong

Processes 2024, 12(11), 2582; https://doi.org/10.3390/pr12112582 - 18 Nov 2024

Cited by 5 | Viewed by 1741

Abstract

The acoustic performance of sound barrier absorption materials utilized in substations is subject to variations due to factors such as sandstorms, corrosion, and rainfall. In this study, a model of the absorbing material was developed based on the Delany–Bazley model using COMSOL simulation software, version 5.6. The influence of porosity and material thickness on the absorption coefficient was analyzed, and the patterns of change were summarized. The results indicated that porosity significantly affected the entire analysis frequency range, while material thickness had a more pronounced impact in the low-frequency range. Building upon these findings, a blended fiber absorption material was formulated through research efforts. Experimental results demonstrated that the aluminum fiber diameter measured 30 microns, while the aramid fiber diameter was 12 microns; additionally, their mass ratio was established at 3:1. The material thickness was determined to be 10 cm with a face density of 2500 g/m², resulting in optimal absorption performance. Durability tests revealed that this material could sustain effective acoustic performance across various complex environments. Finally, simulations and analyses regarding noise reduction effects were conducted within actual application scenarios; it was found that the noise reduction capability of the blended fiber sound barrier absorption material exceeded that of glass wool by 4.78 dB. Full article

(This article belongs to the Section Materials Processes)

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