Hybrid Electrospun–Electrosprayed PVDF–Nanodiamond Composites: Correlating ND Loading with Structural, Thermal, Mechanical, and Piezoelectric Properties

Electrospun nanofiber composites offer versatile functionalities due to their tunable properties and high surface area. This study developed polyvinylidene fluoride (PVDF) nanofibers reinforced with nanodiamond (ND) using a dual electrospinning–electrospraying method, allowing simultaneous fiber formation and filler deposition at ND loadings from (0 to 10 wt%). High-resolution SEM images confirmed uniform, bead-free fibers with evenly distributed NDs, indicating effective processing and strong filler incorporation. Structural analyses by XRD and FTIR showed that ND addition maintained PVDF’s α and β crystalline phases. Thermogravimetric analysis revealed notable thermal improvements, with decomposition onset and maximum temperatures increasing from 417°C to 462°C and 433°C and 471°C, respectively, suggesting enhanced interfacial stability. Mechanically, the composites exhibited a 41.4% increase in tensile strength and a 48.2% decrease in elongation at break, attributed to the restricted polymer chain mobility resulting from improved filler–matrix adhesion. Piezoelectric measurements demonstrated superior performance for the PVDF/ND1 sample, which generated 6.5± 0.49 V and a d₃₃ coefficient of 40.64 ± 1.01 pC/N—approximately double that of pure PVDF. Also, the maximum current reached approximately 0.33 μA for the PVDF/ND1 sample. These results highlight that the integrated fabrication strategy effectively enhances thermal, mechanical, and piezoelectric properties, establishing PVDF/ND nanocomposites as strong candidates for energy-harvesting and advanced electromechanical applications.