Design and manufacture of polyurethane polymer acoustic absorber reinforced with rock wool fiber and evaluation of it Acoustic performance

Abstract

Nowadays, noise pollution is very important, due to harming human health and depriving of peace. One of the strategies of the reductioning sound pollution is application of sound absorption materials. This material is known with porous structure. Polyurethane sphonge with porous structure is one of absorbents used in sound pollution absorption. Polymer foams are materials with a polymer structure that consist of a polymer substrate and a large number of gas bubbles that are dispersed in the polymer substrate during the foaming process. One of the concerns of researchers in relation to polyurethane foam is to strengthen the compressive strength and also to enhance sound absorption, especially at low and medium frequencies using amplifiers. For this purpose, in the present study, we tried to strengthen the sound absorption coefficient and compressive strength of open cell polyurethane foams with different amounts of RWF (0 to 1.5% by weight) after surface treatment to 5% concentration of hydroxide sodium (NaOH) solution. In order to evaluate the structural, physical, kinetic and mechanical properties, polyurethane samples reinforced with different amounts of rock wool fibers (0-1.5 wt%) were synthesized. In the first stage, pure polyurethane foam was synthesized from the reaction of two components A and B, including the reaction of isocyanate and polyol and other additives by free growth foaming method. In the two stage, polyurethane polymer foam reinforced with RWF were synthesized by adding RWF in different weight percentages to PUF. After preparing the samples, tests such as BET test to check porosity, AFR test using NOR1517A system in accordance with ISO9053 / DIN EN 29,053 to determine AFR, fluid saturation method (Archimedes method) to determine density, pressure test By universal traction device to determine compressive strength and stress relaxation, measurement of SAC using domicrophone impedance tube in the frequency range from 63 to 6400 Hz according to ISIRI 9803 standard, to evaluate the effect of reinforcing fibers Sound absorption and electron and light microscopy were performed to determine the role and effect of mineral fibers on the shape and size of the cavities produced. Statistical analyzes included: Regression analysis was performed by stepwise method to detect the effect of non-acoustic factors on sound absorption and Lagrange method to optimize sound absorption. The results of the compression test show the dependence of mechanical properties on the added fibers. That is, by increasing the mineral fibers from 0 to 1.5% by weight, the compressive strength of the samples increased from 0.037 to 0.059 MPa. Microscopic evaluation showed that the mineral fibers used increase the number of cavities and at the same time reduce their size. The results of sound absorption analysis showed that by increasing the percentage of RWFs to PUF, the absorption coefficient increased at all frequencies, especially the middle and high frequencies for all samples. Finally, multiple regression analysis was performed to investigate the relationship between non-acoustic parameters (including airflow resistance, porosity, density and amount of fiber fillers) and sound absorption coefficient. The results showed that there was a significant relationship between non-acoustic parameters and SAC factor (P <0.018). The results of multiple Lagrange modeling using fitting indices analysis showed a good fitting between non-acoustic parameters and sound absorption. Applying mineral fiber surfaces in the structure of acoustic absorbers to increase attenuation and reduce reflections is one of the most effective ways to increase their acoustic adsorption performance. As in the present study, the results showed that by designing acoustic absorbers based on polyurethane polymer compounds, follow it, the use of RWFs in the polymer structure of polyurethane composite, in addition to increasing the mechanical properties, could improve the SAC. Such an approach has been taken for the first time to design and manufacture polymer acoustic absorbers to expand the possibilities of future sustainable design in this sector. Synthetic sound absorbers can be used in any industry, place or product such as construction, road construction, automobile manufacturing, industrial machinery, studios and conference rooms, ventilation systems and military systems where sound absorption is involved