WOOD RESEARCH Volume 67, Number 3, 2022
Xu Sheng, Xu Peng, Du Yuting, and Zhao Puqi

Short notes: A research on the application of industrial by-product calcium sulfate whiskers in paper filling

The basic properties of calcium sulfate whiskers were studied and compared with commercial ground calcium carbonate (GCC) fillers. The modified whiskers were used for paper filling and compared with a commercial precipitated calcium carbonate (PCC). As a result, it shows that when the unmodified calcium sulfate whisker is used to fill the paper, the ash content of the handmade sheet is low because of its dissolution problem. The ash content of the paper increased obviously when the modified calcium sulfate whisker was added, which reached the ash level of PCC filling. In addition, the paper strength increased greatly, but the light scattering coefficient decreased. In addition, the strength property of the modified calcium sulfate whisker filling paper is basically the same as that of the PCC filling paper with 14.99% ash content when the ash content of the modified calcium sulfate whisker filling paper is 21.95%.

WOOD RESEARCH Volume 61, Number 6, 2016
Onur Ülker and Erol Burdurlu

Some mechanical properties of densified and laminated Lombardy poplar (Populus nigra L.)

In this study, it was studied the effects of densification and then lamination processes on some mechanical properties of Lombardy poplar (Populus nigra L.), which is one of the low density tree species. Densification temperatures were 80, 100, 120 and 140ºC and ratios of densification were 15, 30 and 50 %. Furthermore, lamellas with a thickness of 4 mm cut from densified materials were laminated by bonding one on top of the other with urea formaldehyde (UF) and polyvinyl acetate (PVAc) adhesives. Bending, modulus of elasticity, compression and tensile tests were applied by preparing specimens from the pieces. According to test results, the most suitable temperature level was 120°C. As the ratio of densification was increased at this temperature level, increase were observed in the mechanical properties. Also, lamination provided significant increases in the mechanical values compared to laminated but undensified Lombardy poplar. Increases were observed in the mechanical properties reaching 444 % with application of densification and lamination processes.

WOOD RESEARCH Volume 61, Number 4, 2016
Vlastimil Borůvka, Aleš Zeidler, and Stanislav Doubek

Impact of silicon-based chemicals on selected physical and mechanical properties of wood

This study deals with the impact of silicon-based chemicals on selected physical and mechanical properties of wood. Wood of European beech and Scots pine was the testing material used for impregnation using water glass and commercial product Lukofob EVO 50. The impact of the treatment on dimensional stability, bending strength and modulus of elasticity was tested. Wood density was also evaluated. Although the modification using silicon-based staffs resulted in a statistically significant decrease in swelling for both of the tested species, the positive effect of the treatment was accompanied by a decrease in the strength and stiffness of wood. Water glass had a stronger effect on the tested properties from the chemicals we used in our research.

WOOD RESEARCH Volume 63, Number 1, 2018
Ayhan Ozcifci, Mehmet Erdal Kara, and Alperen Kaymakci

Impact of pf and muf adhesives modified with TiO2 and SiO2 on the adhesion strength

The purpose of this study was to evaluate adhesion strength of phenol formaldehyde (PF) and melamine urea formaldehyde (MUF) adhesives modified with nano-technological products on the adhesion strength of different wood species. For this purpose, the effect of nano-TiO2 and nano-SiO2 on bonding performance and structural properties of PF and MUF were researced. And also, TiO2 and SiO2 chemicals were chosen as a rate of 2%, 4%, 6%, 8% within the adhesives. The bonding strength tests of the acquired Uludag fir and aspen boards were measured with a Universal Zwick Roell brand testing device in accordance with TS EN 205 standards. The obtained results showed that the highest bonding strength for Uludag fir wood was 8.27 N. mm-2 with PF adhesive mixed as 8% of SiO2 and the lowest was 5.91 N. mm-2 with MUF adhesive mixed as 2% TiO2, respectively. For aspen wood, the highest value was determined as 7.32 N. mm-2 with PF adhesive into which 8% of TiO2 had been added and the lowest was as 5.55 N. mm-2 with MUF adhesive into which % 6 TiO2 had been added. In conclusion it was determined that compared to the control samples the bonding strength of wood materials manufactured with the addition of nanoproduct into the PF adhesive enhanced the bonding strength by approximately 30% and 40% within MUF adhesive.

WOOD RESEARCH Volume 65, Number 3, 2020
Darius Albrektas, Milda Jucienė, Vaida Dobilaitė, and Raimondas Bliūdžius

The influence of thermal modification on the resistance to water impact properties and strength of wood used in outdoor conditions

In this study the influence of thermal modification on the resistance of wood to the impact of water and mechanical properties and to compare the durability of thermally modified and coated wood products operating in wet conditions was investigated. It was found that the weight of thermally unmodified non-coated oak wood after 48 h of soaking increased on average up to ~ 15%, and the weight of coated oak wood increased up to ~ 8%. If wood was thermally modified, the weight of non-coated oak wood increased up to ~ 9%, and the weight of coated oak wood increased up to ~ 5%. After 168 h of soaking these change is about 2 times larger. In the case of pine wood compared to oak wood these change of weight after 48 h is about 2.0 – 2.4 times and after 168 h about 1.4 – 2.0 larger. It can be stated that wooden constructions intended to be used in very wet conditions should be made of thermally modified wood without coating. Thermally modified wood will have greater dimensional and shape stability. Thermal modification reduces the swell up to 1.6 times in the case of oak, more than 2 times in the case of pine.