WOOD RESEARCH Volume 68, Number 2, 2023
Özlem Özgenç Keleş and Sefa Durmaz

A synergic effect of water-based acrylic resin with boric acid on leachability

In this study, the Scots pine wood samples were impregnated (single treatment) with boric acid combined with two types of water-based acrylic resin (pure acrylic and semi-translucent acrylic emulsion) to limit the boron leaching and improve the decay resistance. The results showed dimensional stability in anti-swelling efficiency and water absorption improved in wood specimens treated with boric acid and acrylic types. While the leachability was over 90% for only 3% boric acid-impregnated wood (control), it was calculated at 36% for acrylic emulsions-impregnated wood. Although there were no weight losses for the unleached woods, it was up to 9% for leached woods impregnated with acrylic resin and emulsion. The 25% acrylic emulsion had no weight losses after the leaching test for Coniophora puteana and Trametes versicolor. The boric acid combined with acrylic resin can improve the leaching resistance with the synergic effect, enhancing resistance against biological threats.

WOOD RESEARCH Volume 67, Number 5, 2022
Uğur Aras, Sefa Durmaz, Süleyman Kuştaş, and Hülya Kalaycioğlu

Influence of pumice powder on some properties of phenol-formaldehyde bonded particleboards

In this study, pumice powder as a volcanic aggregate was added in the particleboards’ production. The effect of various ratios of pumice powder (10%, 20%, 30%, and 40%) on physical, mechanical, thermal and fire resistance properties was investigated. Pumice powder did not significantly affect particleboards’ water absorption and thickness swelling values. However, the mechanical properties were significantly affected with raising pumice powder content. The modulus of rupture and modulus of elasticity decreased up to 46% and 45%, respectively. There was also a decrease in the internal bond strength up to 42%. Conversely, pumice powder improved the thermal degradation temperatures. The onset temperatures increased with increasing pumice powder content above 300°C. Similarly, the pumice powder improved the fire resistance of particleboards up to 7% compared to control samples.

WOOD RESEARCH Volume 67, Number 4, 2022
Sefa Durmaz and Özlem Özgenç

The changes in the surface of flat pressed wood-plastic composites exposed to artificial weathering

In this study, the wood flour content’s effect on the weathering performance of flat pressed WPC was investigated. The high density polyethylene was reinforced with four different wood flour content (10%, 30%, 50%, 70%). The weathering performance of WPC was determined by the 400 h of artificial weathering test. According to the results, the color change is inevitable as long as the wood flour is used as filler. Surprisingly, the highest color change was obtained from WPC containing 30% WF, contrary to 70% of wood flour. Similarly, the whiteness of the surface of WPC increased with exposure time. The photooxidation resulted in the chain scission and shorter molecules, which were observed by ATR-FTIR analysis. The changes in the intensity of characteristic polymer (2914 cm-1 and 2846 cm-1) and wood peaks (1510 cm-1 and 1027 cm-1) exhibited the photodegradation on WPCs’ surface, which resulted in color change. Moreover, the light microscopy investigation showed surface degradation. The extensive weathering conditions caused surface cracks and surface roughness. The visual appearance of WPCs also demonstrated how to change the surface character of WPC during the 400 h of artificial weathering. In conclusion, the increase in the wood content increased the intensity of degradation.

WOOD RESEARCH Volume 67, Number 2, 2022
Sefa Durmaz

Effect of wood flour content on the properties of flat pressed wood plastic composites

This study focused on the effect of wood flour content on some mechanical and physical properties of flat pressed wood plastic composites (WPC). The results revealed changes in the wood flour content affected the density of flat pressed WPC. Moreover, as exposure time increased, water absorption values were increased. The changes in the wood flour content considerably affected the mechanical properties of WPC. The decrease in the flexural strength reached up to 58%, while it was 61% for tensile strength. However, modulus of elasticity increased with increasing wood flour content. Meanwhile, the decrease was inevitable for screw withdrawal strength, where the increase in wood flour content resulted in a reduction of up to 50%. It was clearly determined that wood flour content above 60% evidently affects the physical and mechanical properties of flat pressed WPC, which should be considered in the utilization areas where high mechanical properties are critical.