LIQUID PERMEABILITY OF EUCALYPTUS UROPHYLLA WOOD TREATED WITH DIFFERENT DRYING METHODS

In this study, the influence of three different drying methods on the liquid permeability of sapwood and heartwood of Eucalyptus urophylla was investigated. The liquid permeability of the dried wood was assessed by measuring the maximum amount of dyeing solution uptake using the capillary rise method. Subsequently, the microscopic structure of the dried wood was examined by scanning electron microscopy (SEM). The results indicated that the liquid permeability of sapwood dried by microwave vacuum drying (MVD) and conventional kiln drying (KD) was significantly more effective than that of air drying (AD) treated wood. However, there is no significant difference in the effect of MVD and KD on the liquid permeability of sapwood. The liquid permeability of heartwood treated with MVD is significantly better than that treated with KD and AD, and the effect in the effects of AD and KD on the heartwood is not significant. The increased permeability of Eucalyptus urophylla wood can be attributed to the occurrence of macro-cracking or micro-structural damage in the test specimens, resulting from the dislodgement of perforated plates within the wood cells, the rupture of the intercellular layer between vessel and axial parenchyma cells, as well as the rupture of the pit membrane in cross-field pits due to microwave vacuum drying and conventional kiln drying

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.