Effect of annealing on aqueous stability and elastic modulus of electrospun poly(vinyl alcohol) fibers

Electrospun poly(vinyl alcohol) (PVA) fibers rapidly dissolve in water. Their aqueous stability can be improved by annealing using a combination of controlled temperature and treatment time. The increase in aqueous stability of the PVA fibers is associated with an increase in PVA crystallinity and is defined by X-ray diffraction and the ratio of the Fourier transform infrared spectroscopy band intensities at 1141 and 1425 cm−1. A ratio of intensity of these two infrared bands ≥2.5 or ~75% and above in the degree of crystallinity as determined by X-ray diffraction indicates fiber stability in water. Annealing treatment also results in an increase in the stiffness of the fibers. At a treatment temperature of 135 °C for 4 h, the elastic modulus of the fiber increased by 80%. This information is useful when these fibers are being considered for applications in an aqueous environment such as membrane filter or tissue scaffold.