Enhanced sound insulation properties of microporous PMMA foams by constructing novel multilayered and directional cell structure (MDCS)

Abstract

The main purpose of this study is to improve the performance of soundproofing materials through structure design without any functional phases. The sound insulation properties of PMMA microporous foams with multilayered and directional cell structure (MDCS) were investigated. The influence of the MDCS on sound transmission loss was discussed in detail. In addition, the mechanism for improving the sound transmission loss of the multilayered foams was discussed. The results show that the sound transmission loss value of the multilayered foams is up to 29.70 dB, which is 29.5% higher than that of the single‐layer foams. It is due to the MDCS, which reduces the cell size of the foams, leading to increase the reflection and scattering of sound waves in pores. Meanwhile, the MDCS accompanied by multilayer interfaces increases the multiple reflection of sound waves at the interfaces. Besides, the smaller cell size and higher cell density strengthen the stiffness of the foams, which promotes the sound insulation properties. This study presents a novel and convenient method to design modern sound insulation materials.

Acoustic Absorption Properties of Polystyrene‐Pyrolytic Pinus Resinosa Composite Foams Prepared by Torsion‐Induced Extrusion

“…The sound absorption performance of foam material is sensitive to porosity value and closely related to cellular structure, such as porosity type (open or closed), cell size and distribution, microstructure and stiffness of cell wall, and thickness of foams. [32][33][34][35][36][37][38][39][40][41] In the present research, the porosity varies in the range of 91.7-93.4% with lowest and highest values for 0% and 0.1% of renewable carbon, respectively. Since the differences in porosity values are not significant, the observed variations in sound absorption curves might be explained by cellular structure or cell wall stiffness.…”

“…Such behavior is reported for closed cell foams. [12,[31][32][33] For foam acoustic composites with PR600 renewable carbon in the composition, the behavior is somehow different from the resonant absorber that was expected for systems with closed cell foams, the peaks disappear or get smaller compared with pure PS foam acoustic system. In case of 0.05% renewable carbon foam acoustic system, 𝛼 gradually increase from around 0.2 at 2.2 kHz until it reaches maximum value of 0.45 at 4 kHz, slightly reduces to 0.39 and stable after with frequency increase.…”

Encapsulation of Ammonium Polyphosphate in Lignin Nanocontainers Enhances Dispersion and Flame Retardancy in Polylactic Acid Foams

“…By 2026, for polymer foams, 37 million tons are expected to be produced, with the market reaching USD 170 billion by 2030 . Polymer foams are versatile materials used in energy absorption, construction, insulation, and packaging. − To address disposal issues associated with common polymers, biodegradable alternatives like polylactic acid (PLA) are gaining attention . However, raw PLA exhibits major limitations such as a slow crystallization rate, poor thermal stability, and toughness when compared to its fossil-based counterparts …”