Effect of the passive chemical modification of wood with silicon dioxide (silica) on its properties and inhibition of moulds

This work investigates how wood modification with silicon dioxide affects its selected physical and mechanical properties and resistance to moulds. Silicon mineralization can improve some of the technical properties of wood and extend the service-life of wooden structures. Silicon, which is contained in inorganic and organic-inorganic substances that are used for artificial wood mineralization or is the main component at natural wood mineralization, was used in the form of colloidal silicon dioxide and its various concentrations for pressure impregnation of beech (Fagus sylvatica) and Silver fir (Abies alba) wood samples. Following, physical, mechanical and biological properties of such modified woodswere tested together with waterlogged fir wood stored in water over a long period. Silicon-dioxide did not significantly improve properties of beech and fir woods, probably due to the hypothesis, that none covalent bonds between the silicon and the OH- groups of cellulose, hemicelluloses or lignin could be created in the cell-walls of the silicon-modified woods.

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.

The tensile shear strength of outdoor type plywood produced from fir, alnus, pine and poplar wood

In this study, it is aimed to determine both the tensile-shear strengths of plywood that produced by using phenol formaldehyde resin from Uludağ fir (Abies nordmanniana subsp. bornmülleriana Mattf.), alder (Alnus glutinosa L.), scots pine (Pinus sylvestris L.) and Samsun poplar (77/51 Populus deltoides Bartr.) trees rotary cut veneers combinations of poplar-pine, poplarfir, poplar-alder and poplar wood along with the effect of wood types on adhesion quality of glue. According to standards TS 3969 EN 314-1, and TS EN 314-2 adhesion class 3, the test specimens were prepared and tested for the adhesion quality. The obtained data were analyzed statistically by using SPSS 22 statistical program. As a result, the tensile-shear strength values of poplar, pinepoplar, fir- poplar and alder-poplar plywood types were found to be as averages 1.34 N. mm-2, 1.66 N. mm-2, 2.18 N. mm-2 and 2.46 N. mm-2 respectively. Also, it was found that there was no significant difference between the alder poplar and fir-poplar plywood types about tensile-shear strength. Since these all plywood combinations are satisfied the required 1 N. mm-2 strength value according to TS EN 314-2, all plywood types in this study are of suitable quality for outdoor uses.