Abstract
The solubility parameters of polyacrylonitrile (PAN) and of three different solvents, N, N-dimethylformamide (DMF), N, N-dimethylacetamide, and N-methyl-2-pyrrolidone, as also Flory–Huggins parameters between PAN and these solvents were first calculated, using molecular dynamics simulation. From the simulation results, DMF was chosen as the solvent for PAN in magnetic-field-assisted electrospinning (MFAES). Then, a systematic investigation of the processing parameters, including their interaction and modeling of the degree of fiber alignment, was conducted using a three factor, three-level Box–Behnken design, combined with response surface methodology and quadratic programming. Three independent variables (solution concentration [X 1], ranging from 12% to 14%; voltage [X 2], ranging from 12 to 16 kV; and the distance between two magnets [X 3], ranging from 2 to 3 cm) were consecutively coded as x 1, x 2 and x 3 at three levels (−1, 0, and 1). The degree of PAN fiber alignment (Y) was maximized, based on 17 different MFAES experimental data, and a second-order polynomial regression equation was obtained to predict the corresponding results. The significance of independent variables and their interactions was tested by the analysis of variance with 95% confidence limits (a = 0.05). The standard effects of the independent variables and their interactions on the response were also investigated by preparing a Pie chart. The optimum values of the selected variables were obtained by solving the quadratic regression model and analyzing the response surface contour plots. The optimum coded values of the three test variables were computed as x 1 = 0.35, x 2 = −0.52, and x 3 = 0.15. The experimental conditions at this global point were determined to be X 1 = 13.35%, X 2 = 13.03 kV, and X 3 = 2.58 cm, and the corresponding Y was found to be about 96%.
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