WOOD RESEARCH Volume 66, Number 4, 2021
Jiapeng Wang, Zhenju Bi, Zhangjing Chen, Li Yan, and Yafang Lei

Decay resistance, dimensional stability and mechanical strength of poplar wood modified with plant-derived compounds

The cinnamaldehyde, salicylic acid, stearolic acid and citric acid were plant-derived organic compounds that can be activated to fungi, that could degrade the wood in long term. The compounds with concentrations of 3%, 5% and 7% assisted by different dispersants were impregnated into poplar (Populus nigra L.) specimens by the vacuum-pressure method. After that, weight percentage gain (WPG), decay resistance against white-rot fungi (Trametes versicolor) and brown-rot fungi (Gloeophyllum trabeum), color change, dimensional stability and mechanical properties including modulus of elasticity (MOE) and modulus of rupture (MOR) were measured. The results indicated that cinnamaldehyde impregnated poplar showed antifungi activity against both G. trabeum and T. versicolor, and citric acid impregnated poplar showed antifungi activity against G. trabeum. The color of poplar specimens before and after impregnated cinnamaldehyde and citric acid had a little change, dimensional stability had been improved and mechanical properties especially for MOR increased significantly.

WOOD RESEARCH Volume 66, Number 2, 2021
Sławomir Krzosek, Marek Grześkiewicz, Izabela Burawska-Kupniewska, Piotr Mańkowski, and Marek Wieruszewski

Mechanical properties of polish-grown Pinus Sylvestris L. structural sawn timber from the butt, middle and top logs

The research consisted in testing Polish sawn timber dedicated for construction applications made of pines (Pinus sylvestris L.) that grew in the Silesian Forestry Region, taking into account three parts of the log: butt, middle and top. The boards had the same cross section, a nominal thickness of 40 mm and width of 138 mm, typical for Polish structural timber. The mean nominal length of the boards under research amounted to 3500 mm. Each set was composed of 70 boards. Before the tests, boards were dried in an industrial drier until reaching the moisture content of 12%, and they were planed on 4 sides. First of all, the sawn timber was graded into strength classes, and their dynamic modulus of elasticity (MOE_dyn) was tested with a non-destructive method, with the use of a portable MTG device. The next step consisted in a bending test with four points of support, according to the EN 408 standard, and with the use of the TiraTest 2300 machine, in order to determine the global modulus of elasticity (MOE_EN-408) and the static bending strength, also referred to as modulus of rupture (MOR). Finally, the average growth ring width was determined for each board (PN-D-94021), as well as wood density according to EN-408. The hereby paper presents the test results for all the tested sawn timber boards, taking into account the part of log that each board came from: butt, middle or top. The hereby paper presents the influence of density on the mechanical properties of wood, taking into account the location on the round timber. The analysis does not include the influence of the width of annual growth rings and the proportion of latewood on the wood properties under research.