電聲轉換器是一種常見的能量轉換裝置，其是透過一壓電材料將機械能轉換成電能，在感測、致動與電能產生等運用上，具有低成本及高效率的優勢。
本研究使用廣泛應用於傳感器、電能轉換裝置上的壓電材料聚偏氟乙烯 (Polyvinylidene fluoride, PVDF)，結合靜電紡絲 (Electrospinning, ES) 技術製備出擁有良好壓電性能的PVDF奈米纖維膜，並探討其晶體結構及添加碳材料對PVDF奈米纖維膜的壓電性能之影響。結果顯示，奈米纖維膜的多孔性 (Porous material) 及高比表面積 (Specific Surface Area) 能增加材料與聲波之間的振動及摩擦，得到機械能與電能的轉換，進而達到吸音的效果。而ES同時能有效地誘導PVDF的β結晶相，且添加奈米碳材：奈米碳管 (Carbon Nanotubes, CNTs) 以及石墨烯 (Graphene, Gp) 後更能利用界面極化效應，以增加壓電特性。在吸音性能的部分，加入奈米碳材後除了提升電紡PVDF奈米纖維膜在低頻吸收效果之外，更使吸收區域往更低頻偏移。

Polyvinylidene fluoride (PVDF)-based piezoelectric polymers are of interest for applications in audio transducers. A piezoelectric material subjected to stress or force generates an electrical potential. Thus, reduction in vibrations and noise can be achieved using piezoelectric materials.
In this study, a novel sound-absorbing material was developed using electrospun piezoelectric polyvinylidene fluoride (PVDF) membranes. Effects of conductive materials and electrospinning on the crystal structure and piezoelectric properties of PVDF nanofibrous membranes were examined. Results showed that electrospinning effectively induces the β phase formation and increased piezoelectricity. Addition conductive materials further improved the piezoelectricity through interfacial polarization. Electrospun nanofibrous 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 adding conductive materials into PVDF had higher piezoelectricity and shifted further to a lower frequency region. Thus, the electrospun PVDF/acoustic foam presented herein is potentially a practical and efficient sound absorber because of its favorable absorption performance, particularly in the low- and middle-frequency regions.

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