Effect of Solvents Ratio and Polymer Concentration on Electrospun Polybenzimidazole Nanofiber Membranes Fabrication

Polybenzimidazole (PBI) nanofiber membranes were prepared using electrospinning potential of 15 kV and 0.2 ml/h flow rate at different PBI concentrations (6.5 and 7.5 w/v%) with the solvent mixture ratio (DMAc:DMF) of 1:1 and 2:1, respectively. This study investigated the properties of the polymeric solution and the effects of solvent ratio and concentration on morphology, hydrophobicity and mechanical properties of PBI nanofiber membranes. The solvent mixture ratio and spinning solution properties are not significantly different than the effect of polymer concentration on the viscosity. The viscosity and surface tension of spinning solutions increases with an increase in the concentration of PBI. It was observed that the average diameter of nanofibers was 75 and 97 nm for 6.5 and 7.5 w/v% PBI spinning solution, respectively. Moreover, the contact angle values range from 111 to 125°. This observation reflects that the nanofiber membranes are hydrophobic. Another finding is that the nanofiber membranes with 7.5 w/v% of PBI showed excellent mechanical properties with the maximum stress value of 4.20 ± 0.29 MPa. The finding also shows that the polymer concentration on the spinning solution influences the structure and morphology of the nanofibers. On the other hand, the solvent mixture ratio does not have any significant impact on the nanofiber membranes properties.