Acoustic Properties Improvement of Polyurethane Composite by TC4 ‐ MWCNTs Double‐Layer Hollow Spheres With Multiple Interfaces

ABSTRACT In order to solve the problem of engineering noise, this study explores preparing a novel polyurethane acoustic composite with excellent performance. Hydroxylated multi‐walled carbon nanotubes (MWCNTs) were coated on TC4 hollow spheres (TC4 HS) to create TC4‐MWCNTs double‐layer hollow spheres (TC4‐MWCNTs DHS). A polyurethane/TC4‐MWCNTs DHS composite (PU/TC4‐MWCNTS DHS) was then prepared using polymer casting, with TC4‐MWCNTS DHS as filler and polyurethane resin as matrix. Compared to PU/TC4 HS, PU/TC4‐MWCNTs DHS shows higher sound transmission loss (STL), with increases of 53.6%, 42.6%, 37.6%, 33.6%, 34.0%, and 40.7% at 1000, 2000, 3000, 4000, 5000, and 6000 Hz, respectively. The sound absorption performance of PU/TC4‐MWCNT DHS has also been improved compared to PU/TC4, with a maximum absorption coefficient of 0.88 at 6300 Hz. The enhanced performance stems from the double‐layer structure, which creates multiple interfaces for increased acoustic reflection, and the hollow tubular MWCNTs, which further reflect sound waves internally and prolong their propagation path.