Effect of particle size on the surface properties and morphology of ground flax.

Flax fibers were ground with a ball-mill and four fractions with different size ranges were collected by sieving. These were tested for water sorption, degree of polymerization (DP), copper number, hydroxyl number and analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and inverse gas chromatography (IGC). Significant differences were found between the properties of the flax fiber and those of the ground versions, including fragmentation of fibers, increase of water sorption, copper number, hydroxyl number and surface O/C ratio, and decrease of DP, crystallite size and dispersive component of surface energy (γs(d)). Some parameters depended on the particle size: O/C ratio and hydroxyl number had local maxima at 315-630 µm, while γs(d) increased steadily with the decrease of particle size. These relationships were explained by fiber disintegration, destruction of waxy surface layer, exposure of cellulosic components, increase of surface area and crystalline imperfections.

Degradation of lignin-containing materials by xylanase in biopreparation of cotton.

Solubilization of lignin and carbohydrates from the lignin-holocellulose structure of cotton seed-coat fragments was investigated by UV/VIS spectrometry. Xylanase (Pulpzyme HC) pre-treatment partially destroyed the lignocellulosic structure of the seed-coat fragments, producing reducing sugars and soluble lignin in the supernatant. Furthermore, the pre-treatment by enzyme enhanced the delignification in the subsequent alkaline scouring process and increased the lightness of the substrate.