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 quality of Paraserianthes falcataria L. nielsen syn wood from three year rotation of harvesting for construction application

Paraserianthes falcataria is fast growing species that considered being potential lumber for construction application. The aim was to evaluate the effect of year rotation of harvesting on quality of Paraserianthes falcataria wood for construction application. Nine trees of Paraserianthes falcataria with harvesting rotation of 5, 7, and 9 years, were harvested from the private forest. Moisture content, specific gravity, shrinkage, MOE, MOR, and compressive strength parallel to grain were measured for wood quality parameters in accordance to JIS Z 2101. Durability test were conducted against dry wood termite (Criptotermes cynocephalus Light). The results showed that year harvesting of Paraserianthes falcataria influence significantly on specific gravity, and compressive strength parallels to grain. Paraserianthes falcataria wood is classified into strength class III-IV, which is properly used for light construction. To obtain optimum quality for construction purposes, Paraserianthes falcataria tree is recommended to be harvested in minimum harvesting rotation of 7 years.

An eco-friendly urea-formaldehyde resin: preparation structure and properties

The preparation, structures and properties of UF resin prepared with concentrated formaldehyde at a low molar ratio F/U=1.1 were studied in this paper. According to the results obtained from 13C-NMR, FT-IR and DMA, UF resin prepared with concentrated formaldehyde showed better mechanical properties and heat resistance and lower formaldehyde emission responsible for its high degree of polycondensation and crosslinking than that of UF prepared with common formaldehyde, but its stability was so bad due to its high content of ether bridges. However, it was stated that adding hydrolyzed soy protein to this UF resin at the first alkali preparation stage of “alkali-acid-alkali”, its stability got improved due to the increase of methylene bridges, which was the key contribution to polycondensation.