Central composite design (CCD)-Response surface methodology (RSM) of effective electrospinning parameters on PVP-B-Hf hybrid nanofibrous Cl tar composites for synthesis of HfB2-based composite nanofibers

Electrospinning in order to achieve the new nanofibrous composites by using inorganic precursor and in the lack of defects, like beads or bubbles and having diameter uniformity characteristic is challenging. To synthesis of HfB2, repeatability and homogeneity of raw electrospun fibers of polyvinylpyrrolidone-boron-hafnium (PVP-B-Hf) complex from PVP, H3BO3, and HfCl4 precursors are essential to further applications; for example in synthesis of HfB2. A five-level-five-factor central composite (circumscribed) design (CCD) approach-based response surface methodology (RSM) analysis was applied to statistically specify the effect of important process variables, namely initial PVP polymer concentration (6-14 wt %), applied voltage (10-22 kV), flow rate (4-16 mu lit/min), nozzle-collector distance (10-18 cm), and molar ratio of boron to hafnium (2.2-5.8) on the key response process output variables such as average diameter, quality, and uniformity of the nanofibrous composites. By using this rotatable design, a total of 50 electrospinning experimental data was fitted. The significance of the factors and their interactions were verified by using the analysis of variance (ANOVA) with 95% of confidence level (p < 0.05). Logarithmic conversions of CCD manifested initial PVP concentration and B/Hf molar ratio as the most important process variables regarding accessible nanofibrous composites, while voltage, flow rate, and distance perform much less weighty roles in fibers diameter. The optimal values of the operating parameters to obtain the nanofibrous composites having narrow size distribution were specified. The model demonstrated excellent suitability as a tool to implement and tailor the fibers' average diameter PVP-B-Hf hybrid nanofibrous composites. XRD analysis revealed the formation of HfB2 and residual HfO2 phases after heat treatment of the resulting PVP-B-Hf hybrid nanofibrous composites at 1500 degrees C in Ar flow for 2 h, whereas the obtained HfB2 based nanofibrous composite preserved its excellent fibrillar morphology.