The effects of polymer weight average molecular weight (M-W) on the fiber structure of electrospun polyvinylalcohol (PVA) have been studied. PVA with a degree of hydrolysis of 98-99% and with molecular weights ranging from 9000 to 186,000 g/mol was dissolved in water. The concentration (C) of the polymer in the solution was varied depending on the molecular weight. The solution was electrospun at 30 kV and the sample obtained on the collector was examined by scanning electron microscopy. It was observed that for each molecular weight, a fibrous structure was stabilized above a minimum concentration, generally corresponding to [eta]C>5,. The average fiber diameter was between 250 nm and 2 mum. The fiber diameter increases with M-W and concentration. At low M-W and/or concentrations ([eta]C < 9), the fibers exhibit a circular cross-section. Flat fibers were observed at high M-W and concentrations ([eta]C>9). (C) 2003 Elsevier B.V. All rights reserved.