Effect of Microscopic Internal Structure on Sound Absorption Properties of Polyurethane Foam by X-ray Computed Tomography Observations

Abstract

We investigated several conditions for manufacturing polyurethane foam for motor vehicle application to clarify the effect of the material structure on sound absorption performance in the low-frequency region. The objective is to reduce material weight without reducing noise absorption performance. We investigated the relationship between the internal microscopic structure and absorption performance by 3D analysis of X-ray computed tomography scanning observations. We found that the microscopic structural parameters of the material cells affect the sound absorption frequency and that they have a strong relationship with tortuosity, which is an acoustic parameter of porous materials. We also found that reducing cell size and making the cell frames thicker shifts the peak frequency of the sound absorption coefficient downward.

Recent Advancement in Plant Oil Derived Polyol‐Based Polyurethane Foam for Future Perspective: A Review

“…incorporated magnesium hydroxide into PUF for improving sound insulation properties. Yamashita et al . investigated the effects of internal structure on the sound insulation properties of properties.…”

“…Sung et al [156] incorporated magnesium hydroxide into PUF for improving sound insulation properties. Yamashita et al [160] investigated the effects of internal structure on the sound insulation properties of properties. Addition of nanosilica into PUFs considerably increased sound insulation characteristics and properties of the resulting foam.…”

Mechanical properties of multifunctional foam core materials

“…In general, how the energy of the sound wave is dissipated depends on the flow resistivity of the air within the pore phase, the porosity, and the tortuosity of the void phase within the foam, as well as the dissipation of acoustic energy (as heat) due to viscous and thermal losses [5]. As an example, three-dimensional microcomputed tomography measurements on PU foams show that the peak frequency of the sound absorption coefficient can be shifted downward to lower frequencies by reducing the cell size and increasing the foam density and the thickness of the cell walls and edges [8]. As an example, three-dimensional microcomputed tomography measurements on PU foams show that the peak frequency of the sound absorption coefficient can be shifted downward to lower frequencies by reducing the cell size and increasing the foam density and the thickness of the cell walls and edges [8].…”

The Effects of Various Additive Components on the Sound Absorption Performances of Polyurethane Foams

“…However, to the best of our knowledge, there are few investigations reported on the effects of additive components in the foams. In this study, the sound absorption is characterized by the impedance tube technique to obtain the incident sound absorption coefficients and transmission losses [27][28][29].…”