Noise attenuation inside airplane cabin: Preliminary results on combined porous/nano-fibrous materials

A series of light weight and cost-effective combined system made of poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) nanomembranes doped with carbon nanotubes and cellular materials (aerogel and melamine foams) were prepared and tested. The overall composite system acoustic behavior was affected by each of its individual constituents. The hypothesis of a Helmholtz resonator-like behavior caused by the combination of nanomembranes and cellular materials was proved experimentally and by analytical models. The proposed analytical correction of sound absorption coefficient (α) was able to capture the resonant effect “physical phenomenon”. The aerogel by itself is not an effective sound insulation component, but the nanomembrane + aerogel association can lead to sound absorption coefficients of around 0.7 with a thickness around 4.0 mm at 6000 Hz frequency. The melamine foam + nanomembrane has its sound absorption coefficient peak at ∼0.97, at 1600 Hz with a thickness of 12 mm. The changes in melamine foam (density ∼6 kg/m3) frequency from high range (5500 Hz) to mid-range (1600 Hz) with the addition of ∼60.00 µm thick nanomembrane, opened a new venue for a new class of cellular composites for acoustic insulation of commercial airplanes cabins.