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 beta phase formation and increased piezoelectricity. Adding CNTs further improved the piezoelectricity through interfacial polarization. Electrospun nano fiber 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. (C) 2016 Elsevier Ltd. All rights reserved.