WOOD RESEARCH Volume 61, Number 4, 2016
Eliška Oberhofnerová and Miloš Pánek

Surface wetting of selected wood species by water during initial stages of weathering

Currently, the trend of using untreated wood elements in the exterior is becoming more progressive. The rainwater nevertheless needs to be recognized as an important factor increasing photo-degradation of wood and causing other damages as splits, cracks and deformations. The aim of this work is to determine the influence of initial stages of weathering on wetting properties of wood surfaces evaluated by the contact angle measurements using goniometer Krüss DSA 30E. Nine wood species were tested during 12 months of weathering: spruce, larch, pine, Douglas fir, oak, black locust, maple, alder and poplar. The lower decrease of the contact angle of water drop was observed on maple, alder and black locust surfaces, which predicts higher durability and slower degradation during weathering. On the contrary, the higher decrease of contact angle and higher hydrophilicity of wood surfaces was observed on all softwoods and oak and poplar as well.

WOOD RESEARCH Volume 63, Number 3, 2018
Magdalena Woźniak, Izabela Ratajczak, Barbara Lis, and Tomasz Krystofiak

Hydrophobic properties of wood traeted with propolis-silane formulations

The study presents results of hydrophobic properties examination of Scots pine wood treated with a propolis extract and two propolis-silane formulations determined by contact angle analysis and water uptake test. From contact angles data the surface free energy and its shares as well as the work of adhesion were calculated and described in this paper. Treatment with the ethanolic extracts of propolis (EEP) and the propolis-silane formulations a water repellent property of treated wood when compared to control wood. Addition of silicon compounds to the propolis extract caused decreased of the water uptake and increased of the contact angle value of treated wood. The most effective hydrophobic effect was obtained using the impregnation with the formulation based on EEP and organosilanes: vinyltrimethoxysilane (VTMOS) and tetraethyl orthosilicate (TEOS).

WOOD RESEARCH Volume 63, Number 2, 2018
Zhi Liu and Jinzhen Cao

Fabrication of superhydrophobic wood surface with a silica/silicone oil complex emulsion

The superhydrophobic wood surface was fabricated in this study by impregnating oven-dry poplar (Populus cathayana Rehd.) samples with a silica/silicone oil complex emulsion (SSOCE), mainly composed of two silicone oils(hydroxy silicone oil and hydrogen silicone oil) and two different sized silica particles (micron and nano scaled, respectively). Different concentrations of the complex emulsion (5%, 10%, 20%, 30% and 40%) were used and their effect on static contact angles (CAs) and surface free energy (SFE) of wood were investigated. The chemical and morphological changes of modified wood surface were characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). The superhydrophobic wood surfaces were manifested by the water CA of about 154.8° on the transverse section, 151.3 °on the tangential section and 150.2° on the radial section, respectively. It was confirmed that silicone oilsin the complex emulsion formed a silicon resin filmand uniformly attached on the wood surface, with silica particles in micron and nano scales helped to make the surface rougher.

WOOD RESEARCH Volume 65, Number 6, 2020
Igor Novák, Angela Kleinová, Ivica Janigová, Matej Mičušík, Ján Sedliačik, Miroslav Šlouf, Pavlo Bekhta, Ján Matyašovský, and Peter Jurkovič

Properties of water steam-treated maple wood (Acer pseudoplatanus L.)

The hydrothermal treatment of maple (Acer pseudoplatanus L.) wood by steam represents the modification method with the effective heat transfer, which can improve industrially significant properties of wood, i.e. its color, hydrophobicity and subsequently dimensional stability. The maple wood was modified by steam at 125°C during 8 hours, and at pressure of 0.18 MPa. The water contact angle of steam-treated maple wood increased from 44.9° (for untreated maple wood) to 55.3° (for steam-treated maple wood), and the stability of water drop on steam-treated maple wood surface increased. FTIR spectra show an increase in C=O and glycoside bonds concentration on the surface of steam-treated maple wood, but the concentration of C-O-C groups decreased. SEM micro photos confirmed the deformation and shrinking of maple wood cells due to steam treatment. XPS measurements confirmed, that the concentration of oxygen as well as C=O and C-O-O groups on the surface of steam-treated maple wood showed a slight decrease in comparison with pristine wood sample.

WOOD RESEARCH Volume 65, Number 3, 2020
Ruyuan Yang, Xiaofeng Zhang, Youfu Sun, Tingting Zhou, and Quan Yuan

Effect of the metallization treatment on the surface properties of Populus euphratica

To improve the surface-finishing performance and enhance the protection of surface coatings, this study employed metallization treatment of fast-growing poplar through an orthogonal experiment. The poplar specimens were impregnated using a low-melting point alloy at different temperatures (75°C, 85°C, 95°C), pressures (0.5MPa, 1 MPa, 1.5 MPa), and times (0.5h, 1h, 2h) to obtain the optimum process parameters and determine the paint film adhesion of metalized poplar. The test results showed that the impregnation effect was obvious with an increase in the pressure and time. The optimum process parameters were 0.5 MPa, 85°C, and 1 h. Contact angle of the treated wood increased, the surface free energy dropped to some extent, wetting property of tread wood decreased. Whether the treated wood or the untreated wood, film adhesion of treated wood got a higher level. After anti-aging treatment, the treated poplar still had a higher level of film adhesion.