Polymorphism, piezoelectricity and sound absorption of electrospun PVDF membranes with and without carbon nanotubes

In this study, a novel sound-absorbing material was developed using electrospun piezoelectric Polyvinylidene fluoride (PVDF) membranes. Effects of carbon nanotubes (CNTs) and electrospinning on the crystal structure and piezoelectric properties of PVDF/CNT nanofiber membranes were examined. Results showed that electrospinning effectively induced the β phase formation and increased piezoelectricity. Adding CNTs further improved the piezoelectricity through interfacial polarization. Electrospun nanofiber membranes exhibited high surface area providing a large number of contact sites with the sound waves. This resulted in higher sound energy absorption in the middle-frequency region by friction/vibration mechanisms. The piezoelectric electrospun PVDF samples are crucial in converting sound energy to electric potential and absorbing sound waves in a low-frequency region. Sound absorption of the electrospun PVDF/CNT membranes with the highest piezoelectricity was shifted further toward low-frequency region. It was shown that electrospun PVDF covered acoustic foam is an efficient sound absorber because of its favorable absorption performance, particularly in the low- and middle-frequency regions.