Acoustic damping flexible polyurethane foams: Effect of isocyanate index and water content on the soundproofing

Abstract

High-efficiency sound absorbing flexible polyurethane foams (FPUFs) are manufactured using nonpolar polyester resin, methylene diphenyl diisocyanate, and other reagents by one-shot bulk polymerization. In this study, the impact of the isocyanate index (90, 100, and 110) and water content (2.5 and 5%) on the microphase separation and soundproofing behavior of FPUFs are examined using atomic force microscopy, Fourier transform infrared spectroscopy, optical microscope, and an impedance tube device. The results reveal that the increase of the isocyanate index and water content leads to the increase of the cell size, cell size distribution, open-cell content, cell wall roughness, and microphase separation. Also, maximum sound absorption coefficient (α) reaches to 0.98 and the average of α in the frequency range of 1500-4000 Hz increases from 0.7 to 0.87 by increasing the water content from 2.5 to 5% and isocyanate index from 90 to 110; therefore, acoustic damping performance enhances up to 26.24% due to the synergic effects of microphase separation on the viscose media formation, open-cell content, cell wall roughness, cell size, and cell size distribution. In conclusion, FPUFs with an optimal amount of microphase separation and drainage flow can be a promising candidate for sound insulating materials.

Research on Acoustic Absorption Properties of Aramid Honeycomb Composite Material Reinforced by Polyimide Foam

“…After the sound wave entered composite samples, due to the porous structure of IBPIF, the sound wave would continue to reflect and propagate inside, resulting in the vibration of the air inside the sample, causing friction between air molecules and friction between air molecules and the cell wall to convert a part of sound energy into heat energy. [30,[36][37][38] In addition, because IBPIF was filled in the separated core of ARHC, IBPIF was surrounded by honeycomb walls of pure aramid. Therefore, during the sound wave propagation, the honeycomb wall also played a certain role in reflection and increased the propagation path of the sound wave inside the sample, and finally achieved the absorption for the sound wave.…”

“…Considering that the sound absorption performance of polymeric foam is mainly affected by the cellular structure and the most intuitive and effective route to adjust the cellular structure of IBPIF is the foaming agentwater, the dosage of water in the formulation of foaming slurry is set as a variable parameter to study the effect on sound absorption of ARHC filled by IBPIF and select the optimal formula to produce composite material of ARHC filled by IBPIF. [26][27][28][29][30] After this study, the ARHC with excellent sound absorption property can be obtained, and the results will lay a solid foundation for the wider application of ARHC.…”

Biobased and Recyclable Polyurethane for Room-Temperature Damping and Three-Dimensional Printing

“…Note that most of the sole materials are cross-linked rubber that cannot be recycled and degraded. A considerable amount of literature has been published on PU damping materials, showing that it is challenging to simultaneously achieve a high loss factor, wide range, and room-temperature damping. − Most of the commercial PUs are derived from petrochemical resources. Taking full advantage of the renewability and degradability of PLA and the toughness of the PU elastomer is a potential strategy to overcome brittleness and maintain the advantages of both PLA and the PU elastomer, respectively.…”

The effect of OMMT reinforcement and annealing treatment on mechanical and thermal properties of Polyurethane Copolymer nanocomposites

“…10 Therefore, the degree of phase separation increases with respect to the increasing of hard segment content, 11 molar ratios of chemistries, 12,13 polyol type [14][15][16] and chain extender. 17 By nominating the synthesis method, molar ratio and type of diisocyanatos accurately, polyols and chain extenders can tune the chemical structure of polyurethane according to the desired physical, mechanical and thermal properties. 18 The purpose of incorporating various forms of filler into a polymer matrix was to improve the required physical and mechanical characteristics of polymer composites.…”