Katoh et al. [71] improved upon the fiber-forming capabilities of aqueous keratin solutions using
poly-(vinyl alcohol) (PVA). PVA acted to increase the viscosity of the spinning dope, which allowed
fibers with a keratin content ranging from 13−46% to be spun. Due to the fragility of fibers with high
amounts of keratin, the maximum keratin content for sufficient fiber formation was determined to be
30%. This combination of keratin and PVA proved to be advantageous in terms of mechanical
strength, waterproof characteristics, and the adsorption of toxic substances. According to the authors,
keratin-PVA fibers are expected to have wide-spread industrial applications as absorbents for toxic
substances such as heavy metals ions and formaldehyde gas