Sound absorption properties of spiral vane electrospun PVA/nano particle nanofiber membrane and non-woven composite material

In this research, we fabricated a series of PVA membranes loaded with 0 wt.%, 1 wt.%, 3 wt.%, 5 wt.% ZrC and 0 wt.%, 1 wt.%, 3 wt.%, 5 wt.% TiO2 using a spiral vane electrospun machine respectively. There were 2 sizes of TiO2 nano particles: 10 nm and 200 nm. We tested sound absorption properties of needle-punched nonwovens as well as the composite of nano membranes and needle-punched nonwovens by an impedance tube at the frequency range from 500 Hz to 6500 Hz. Besides, we tested morphological characterization of nano membranes by scanning electron microscope (SEM) and crystalline properties by X-ray diffraction (XRD). We investigated the sound absorption properties of composites as well as the effect of ZrC, TiO2, nano particle sizes and cavity depth on sound absorption properties. Results showed that sound absorption properties of composites increased at the whole range of frequency compared to those of needle-punched nonwovens. When loaded with ZrC nano particles, sound absorption properties of composite shifted to a higher frequency region, and with increasing content of ZrC, sound absorption properties were better above 2500 Hz. However, when loaded with TiO2, sound absorption properties were better at lower frequency. With 3 wt.% TiO2, sound absorption coefficient reached the best at the frequency range from 500 Hz to 1500 Hz. Besides, 200 nm TiO2 was more conductive to the increase of sound absorption properties at lower frequency region compared to 10 nm TiO2. Sound absorption properties of composites with air back cavity shifted to a lower frequency region, too. SEM showed that there was nano particle aggregation when loaded TiO2 nano particles. XRD showed that ZrC nano particles loaded in PVA nano fiber retained their crystalline structure while TiO2 didn't. It appeared from the results that nano particles had an effect on sound absorption materials, with different kinds and different sizes, sound absorption properties will improve in different ranges of frequency.