No abstract

Polyacrylonitrile (PAN) and polymethylmethacrylate (PMMA) blend nanofibers produced using electrospinning and mat morphology were studied. The response surface method (RSM) was exploited to optimize the diameter and its standard deviation of the electrospun PAN/PMMA non-woven membranes. The diameter and its standard deviation were related to the solution concentration, applied voltage and PMMA composition. The morphology of the nanofibers was studied by means of field emission scanning electron microscopy (FE-SEM). The importance of the parameters and their interactions were investigated through the analysis of variance (ANOVA). The nanofibers diameter increased with the solution concentration and decreased with the applied voltage. The data showed that the diameter of the nanofibers decreased with PMMA composition, up to 50%, and then increased with further increase of PMMA composition. Some important interactions between the parameters were detected.

Residual contaminants in processed packaging material could migrate into foodstuffs and alter their quality. To measure contaminant transfer rate through wrapping material, a diffusion cell adapted to "head space" gas chromatography was created in our laboratory. It was composed of two chambers separated by the film to be studied, e.g. low density polyethylene film. A 15 μl mixture of liquid n‐propanol and benzene was deposited in the lower chamber of the cell. At 60°C vaporized contaminant diffused through the low density polyethylene film. After calibration, chromatographic analysis of the upper chamber atmosphere allowed measurement of contaminant concentration for various diffusion times. From these results contaminant diffusivities were calculated to be 3.5×1011, 3.9×1011 and 10.4×1011 m2 s1 for 1‐propanol, 2‐propanol and benzene respectively. It was demonstrated that the method was sensitive and allowed precise determination of contaminant diffusivity. © 1997 John Wiley & Sons, Ltd.