Investigation of the rheological response of a bio-liquefied formaldehyde resin-based precursor for electrospinning

To explore the feasibility of applying rheological methods to the electrospinning process, the relationship between the rheological behavior and electrospinning performance was investigated using PEO and PVA as two electrospinning assistant agents with bio-liquefied formaldehyde resin (BLF) as electrospinning precursor. The basic properties, such as viscosity, conductivity, and surface tension were determined by measuring the parameters of the precursors. The steady-state rheological behavior of the precursor was tested, and spinnability was analyzed in terms of its zero-shear viscosity, shear-thinning behavior, relaxation time, and structural viscosity. The dynamic rheological behavior of the precursors was tested, and the viscoelastic and flow processing performance and their influence on the fiber morphology were analyzed in terms of structural strength, linear viscoelastic zone limit, and sol-gel transition point. The appropriate configuration parameters of the precursor and electrospinning process parameters were quantitatively deduced through the above analysis and further verified by electrospinning test and the fiber SEM images. The results showed that rheological analysis can be used as a theoretical basis to predict the spinnability of BLF-based precursors and to optimize its electrospinning process, which can guide the regulation of new biomass-derived electrospun fiber structures and improve the fiber quality.