Influence of the hydrodynamic degumming process on the quality of decorticated flax fibers

The study explored the impact of the hydrodynamic degumming process applied for decorticated monomorphic flax on fiber quality. The experiment was designed as the first stage of research leading to the development of a method for decorticated flax fiber elementarization and cottonization; in particular, effectively dividing the fiber bundles to ensure low linear density and reducing impurities in the content, to make the fibers suitable for cotton spinning systems. The degumming process of the decorticated fibers covered hydrodynamic disposal of the gluing substances, mainly pectins from the fibers, with use of a specially designed lab-scale Model Device for Physical Degumming of the Flax Fibers. The degummed fibers were tested for linear density, length, impurity content and chemical composition by thermogravimetric analysis combined with the analysis of evolved gases (Fourier transform infrared spectroscopy) and analysis of images of fiber cross-sections and longitudinal views from a scanning electron microscope. The study outcomes allowed us to determine the optimal parameters of the degumming process applied for decorticated flax fibers, in which the obtained fibers were of the highest quality. It was found that the optimal parameters of the process were a bath temperature of 30°C and a degumming process duration of 24 hours. These lab-scale process conditions were used in further work on the degumming process of flax fiber carried out on a semi-technical scale, followed by a mechanical cottonization of the fiber, at the final stage of the technological chain.