Electrospun Ultrathin Poly(vinyl alcohol) Fibre Assemblies Modified by Means of Polycarboxylic Acid / Sodium Hypophosphite

A viscous solution consisting of poly(vinyl alcohol) (PVA), butane-1,2,3,4-tetracarboxylic acid (BTCA) and sodium hypophosphite monohydrate (SHP) has been prepared and subjected to an electrospinning process in an attempt to produce BTCA-crosslinked ultrathin PVA fibre mats. At elevated temperatures the carboxyl groups of BTCA react with the hydroxyl groups of PVA via a five-membered cyclic anhydride thus forming ester linkages. The measurement of the fibre diameters of the electrospun fibres created at various high voltages (10, 15, and 20 kV) revealed that the diameters of the fibres were in the range of 0.98 - 1.20 μm. Single layer and double layer fibre assemblies were prepared and thermally treated at 180 °C. The as-prepared ultrathin PVA fibre assemblies were analyzed by means of scanning electron microscopy (SEM), indicating that the morphology of the fibres had been changed. Fourier transform infrared/attenuated total reflection spectroscopy (FT-IR/ATR), X-ray powder diffraction (XRPD) and physical properties, such as water vapour absorption (WVA), water vapour transmission (WVT) and tensile strength were evaluated. The incorporation of BTCA resulted in an increase of WVA and a decrease of WVT. The tensile strengths of the cured PVA mats were remarkably decreased, when BTCA/SHP had been added.