Subwavelength structure for sound absorption from graphene oxide-doped polyvinylpyrrolidone nanofibers

We study the sound absorption of the reinforced polyvinylpyrrolidone nanofibers with graphene oxide. It is shown that reinforced nanofibers can acquire impedance-matched surface to airborne sound at special frequencies. To obtain such surface, nanofibers were spun with polyvinylpyrrolidone polymer that was doped by graphene oxide with concentrations of 0, 6 and 12 wt%. It was found that fibers without graphene oxide were spun continuously and randomly, whereas by doping with graphene oxide, the mode of fibers is changed and some nodes form on the fibers coating. The sound absorption coefficient was measured by an impedance tube based on 105341-1 ISO standard. Measurements in the frequency range from 700 to 1600 Hz show that use of graphene oxide as a reinforcing phase increases sound absorption coefficient of the samples at a frequency similar to 1500 Hz up to similar to 40%. Angular eigen-frequency and dissipation coefficient of the samples were obtained by impedance measurement for the prepared samples. Results show that doping the polymer with graphene oxide causes an increase in the angular eigen-frequency and the dissipation coefficient.