WOOD RESEARCH Volume 70, Number 2, 2025
TAMAS HOFMANN, LASZLO TOLVAJ, and ZOLTAN PASZTORY

CHEMICAL CHANGES DURING WOOD CUTTING

Scots pine (Pinus sylvestris) and poplar (Populus euramericana) species were chosen for the experiments.Sawdust was made by a circular saw with a rare tooth spacing for producing bigger particles beside the fine fractions. Particles were separated by a vibration separator with the sieve sizes 1 mm, 0.63mm, 0.315 mm, 0.1 mm and 0.063 mm. Infrared reflectance spectra of the particles were measured to determine the chemical changes generated by the cutting procedure.The experimental results showed that the grinding of wood resulted in bond rupture for all ether bond types appearing in the infrared spectrum. The number of conjugated and unconjugated carbonyl groups in the wood was significantly reduced during the cutting procedure. After bond breaks, oxidation and recombination processes occurred generating compounds similar to the aromatic structure of lignin, which were shown by increases in absorption at 1514, 1271 and 1231 cm-1

WOOD RESEARCH Volume 66, Number 5, 2021
Tomasz Ozyhar

Short notes: Application of mineral filler in medium density fiberboard (Mdf) and its effect On material properties as a function of particle size

The addition of inorganic filler material in medium density fiberboard (MDF) and the effect on material properties as a function of particle size was examined. Medium density fiberboard was manufactured in a laboratory scale environment to a target raw density of 750 kgm-3. Wood fibers were replaced by using calcium carbonate at 3 and 10 wt.% using fillers with weighted median particle sizes of d50 = 2.0 μm and d50 = 30 μm, respectively. Urea formaldehyde resin was used as binder in all MDF. The influence of filler addition on the modulus of elasticity, bending and tensile strength, dimensional stability and liquid permeability was investigated. The results demonstrate the effect of filler content and its dependence on particle size. The addition of filler with d50 = 30 μm does not have any influence on material properties up to a filler content of 10 wt.%. Using the finer filler with d50 = 2.0 μm at 10 wt.% filler, the quantity significantly increases the water adsorption and swelling behavior and reduces the strength properties of the MDF.