WOOD RESEARCH Volume 69, Number 3, 2024
MERYEM KACMAZ UNVER, MUSTAFA ALTUNOK, and SEKIP SADIYE YASAR

THE INVESTIGATION OF NATURAL AGING BEHAVIOR OF SOME WOOD SPECIES MODIFIED WITH NATURAL PRESERVATIVES

This study evaluates the effects of 12-month outdoor weathering on Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea L.) woods modified with tannins. Wood specimens were divided into four groups: Group A (control, natural aging (NA)), Group B (NA + 100% walnut tannin (WT)), Group C1 (NA + 50% WT and 50% pine tannin), and Group C2 (NA + 50% WT and 50% oak tannin). Group A showed density decreases of 4.3% for Scots pine and 4.7% for sessile oak, while Group B samples exhibited density increases of 2.6% and 1.6%, respectively. Group A specimens had hardness losses of 36.3% for Scots pine and 28.7% for Sessile oak, compared to reduced losses of 8.8% and 11.2% in Group B. Bending strength and modulus of elasticity also decreased significantly in Group A but were minimally affected in Group B. These results indicate that tannin treatments, particularly walnut tannin, improve wood durability and mechanical performance, offering an eco-friendly alternative to conventional treatments

WOOD RESEARCH Volume 68, Number 3, 2023
Mehmet Gunes and MUSTAFA ALTUNOK

Investigation of Bending Strength of Tannin Impregnated Wooden Beams after Heat Treatment

In this study, the changes in bending strength were investigated by applying heat-treatment to laminated beams modified with acorn tannin to improve the mechanical properties of wooden load-bearing structural members. For this purpose, acorn tannin was impregnated on samples prepared from Scotch pine (Pinus sylvestris L.), oak (Quercus petraea L.), and chestnut (Castanea sativa Mill.) woods. Heat treatment was applied to the samples impregnated with acorn tannin at 150ºC for 3 hours. Untreated, heat-treated, and tannin-modified samples were conditioned until they reached constant weight at 20ºC at 65% relative humidity (RH), 40ºC at 35% RH, and 10ºC at 50% RH. Bending resistance tests were applied to the elements that are conditioned in outdoor conditions according to ISO 13061-3. The results of bilateral interaction between tree species and treatment type were compared, the highest bending strength increase was found in Scotch pine samples by 5% compared to control samples.

WOOD RESEARCH Volume 62, Number 3, 2017
Aytekin Onduran, S. Sadiye Yasar, and MUSTAFA ALTUNOK

Investigation of the effects of some modification process to the mechanical performance and deformation of the woodwork

In this study, wood modification (thermo-processing and impregnation) and outdoor conditions of storage (natural aging) the effects on the mechanical performance of industrial woodwork was investigated. For this purpose, naturally grown in Turkey and the commercial value of high Scots pine (Pinus sylvestris L.) and chestnut (Castanea sativa Mill) wood was used. Experimental examples are specifically woodwork has been applied in actual size. Considering the previously conducted research literature only diagonal L-type samples used, not on the actual size samples of woodwork. In addition, there is no study that the combination of the heat-treatment and impregnation. This reveals the original values of this study. For preparing of samples is used the double tenon-mortise corner joint from constructions method and as glue polyurethane based Desmodur VTKA and Polyvinyl acetate based two-component D4. Diagonal woodwork test samples prepared by Thermo S class (185°C temperature with a thermo-vapor process protections) applying. After application of the heat treatment, the test samples impregnated with a solution of 95 % natural pine cone resin and %5 pine tannin by dip method (2 hours). Then, the untreated samples (control), only heat-treated samples and heat treatment + impregnated samples kept for 1 year with outdoor conditions (aging). At the end of the aging, the samples tested according to the principles stated in TS 2472 and TS 7251 EN 107 standard. As result, the performance of woodwork decreased after aging in untreated and heat treatment pieces, the other side after aging – heat treatment, impregnation materials increased the values. The deformation value of woodwork increased after aging most untreated materials, Heat treatment and heat treatment-impregnated reduced aging effectiveness.