STRUCTURES OF SOUND ABSORBING AND THERMAL CONDUCTIVITY COMPOSITE FROM RAW RENEWABLE MATERIALS

ABSTRACT

Renewable raw materials, including natural fiber sources, are the future of storage resources with a variety of positive effects on both the planet ecosystem and the living and working environment, and the energy consumption of delivering the required functionality. Noise reduction is a significant component in creating a professional and suitable work environment as open-plan offices have become a quintessential trend of the 21st century. The most common solutions in noise control include installation of noise absorption barriers and acoustic systems. Bio-based materials show good sound absorption performances, at the same time leaving much lower environmental impact than traditionally used synthetic materials. One of the most important energy-saving types is to reduce energy consumption in buildings by insulating them. Research is focused on designating the optimal structure of composite materials in order to obtain a material with high textural qualities of the surface and a noise absorption level that reaches an average noise absorption coefficient value of αw = 0,5 in at least one set of specified frequencies. Following variables were analyzed in the research: the proportion rate of wool and wood shaving fibers, the panel layer thickness within 15mm – 25mm range, the number of layers per sample material. For measuring the acoustic properties of the sample materials an impedance tube was used. The measurements were carried out in 8 different sample categories, total of 40 samples were prepared and tested. After obtaining sound absorption coefficients, three samples with the highest sound absorption indices were selected for thermal conductivity measurements.

Keywords: noise absorbing materials, renewable biological composite materials, noise reduction coefficient, thermal conductivity