Enhanced Low Frequency Sound Absorption of Bilayer Nanocomposite Acoustic Absorber Laminated with Microperforated Nanofiber Felt

Abstract

A laminar nanocomposite sound absorber was fabricated by laminating a microperforated nanofiber felt (MPNF) on a reinforced nanofibrous cryogel. The spatial morphology of both dense and porous nanofiber layers combined with the microperforations employed on the dense layer delivered a sound absorption average (SAA) rating of 0.61. A lower frequency average sound absorption coefficient of 0.56 was achieved when a denser nanofiber felt layer with the incorporation of 1.78% microperforation rate was employed. A highly porous cryogel layer permits excellent mid- and high-frequency absorption coefficients of 0.74 and 0.51, respectively. The nanocomposite sound absorber has a remarkable areal density of 771 g m–2, making it lightweight and less bulky ideal for acoustic building material. The perforated nanofiber felt, however, has a minimal effect on the sound transmission coefficient (STC) of the nanocomposite sound absorber with an STC of 6.75 dB. By tuning the perforation diameter, perforation rate, and thickness of the nanofiber felt, the overall acoustic absorption performance of the nanocomposite sound absorber can be improved.

Influence of Cross-Linker Functionality and Photoinitiator Loading on Network Connectivity and Actuation in 3D-Printed Model Thermosets

“…Many investigations of hygromorphic actuators focus on tuning the properties of the active layer to tune the overall properties of the resulting shape change. , This investigation aims to highlight the passive layer as the tunable handle for responsive devices through discrete changes in formulation. Though other efforts have demonstrated promising results in tuning actuator response through the addition of metals or fibers, significant changes in formulation can introduce complications such as delamination, especially in 3D-printed systems. ,− This demonstration highlights the ability to utilize model resin formulations that can overcome these challenges while enabling tunability and describes how chemistry-derived thermomechanics dictate the functional properties of printed parts.…”