Flax fibers contain cellulose and different impurities (hemicelluloses, lignin, pectin, waxes and fats,
mineral salts, natural coloring matter and water soluble compounds). From the ecological and industrial
aspect, hydrogen peroxide is the most acceptable component for modification of flax fibers. The aim
of the modification of flax fibers is to remove non-cellulose components and improve the fiber quality
without significant changing of the mechanical properties. Flax fibers were treated with hydrogen
peroxide solutions at concentrations 1%, 2% and 4% at 50 °C, 80 °C and boiling temperature for time
period of 60 min. With the removal of non-cellulosic substances from fibers, it has been achieved a high
degree of fiber separation and a significant increase of modified fibers fineness. The value for fineness
of modified fibers was reduced about 2-4-fold and the modified flax fibers were softer to the hand,
unlike unmodified fibers that are very coarse and stiff. However, the weight loss and removal of lignin,
which gives the fibers strength, as well as a partial damage of the cellulose itself during the severity of
treatment, brought to reduction in the tensile strength of the modified fibers.
