Maderas. Ciencia y Tecnología

The effects of thermal aging on color and glossiness in UV cured coatings applied to sessile oak

Sırrı Şahin, Ümit Ayata, Bruno Esteves — Fri, 04 Oct 2024 00:00:00 -0300

Color and glossiness are two important aesthetic properties of wood flooring and wood furniture that significantly affect consumers choice. With time the coating deteriorates altering the surface properties. Understanding these changes is important for furniture industry, impacting design choices, material selection, and long-term maintenance.

The effects of thermal aging (30 °C for 30 days, 60 °C for 60 days, and 90 °C for 90 days) on color parameters (C*, L*, b*. a*, h^o) and glossiness on both perpendicular (⊥) and parallel (║) directions at 20°, 60°, and 85° angles in UV-cured coatings applied on sessile oak were studied. Results show that statistically significant differences were observed in the glossiness values, as well as in C*, b*, a*, L* and h^o. As the temperature and duration of the thermal aging process increased, there was a noticeable increase in the values of color parameters b*, a*, and C*, while the values of h^o and L* decreased. The characteristics of the surfaces exposed to thermal aging have undergone a complete transformation.

Some physical and mechanical properties of particle boards produced with hazelnut husk and astragalus (Astragalus membranaceus) plant

Selim Karahan, Cengiz Guler — Wed, 09 Oct 2024 00:00:00 -0300

In this study, under laboratory conditions, hazelnut husk and astragalus plant were mixed separately into black pine wood chips, and multi-purpose boards were produced from the obtained chips with urea formaldehyde glue. After the hazelnut husk and astragalus plant were dried and ground, they were added to the chip and glue mixture in certain proportions. Hazelnut husk mixture ratios were applied as 100 %; 0 %, 75 %; 25 %, 50 %; 50 %, 25 %; 75 %, 0 %; 100 % to black pine wood chip in the particle board mixture. These ratios were made in the same way for the astragalus plant. From these mixtures, chipboard blanks of 16 mm thickness and densities between 0,68 g/cm³ and 0,72 g/cm³ were produced. Density, moisture content, thickness increase, water intake, bending strength, modulus of elasticity in bending and tensile strength perpendicular to the surface were tested in physical and mechanical experiments. According to the results obtained, as the participation rate of hazelnut shells and astragalus increased, the durability properties of the panels decreased. At the same time, it shows that the technological properties of the panels produced by adding up to 25 % astragalus plant and hazelnut shells to the mixture comply with the standards.

Thermal modification of fast-growing Firmiana simplex wood using tin alloy: Evaluation of physical and mechanical properties

Kufre Edet Okon, Nkolika Ndulue — Fri, 11 Oct 2024 00:00:00 -0300

Wood is an important structural material, but some undesirable properties limit its application in construction. This study investigated the effect of tin alloy thermal modification (TTM) on selected physical and mechanical properties of Firmiana simplex (Chinese bottletree) wood. Tin alloy thermal modification of F. simplex was performed in a tin alloy bath at two different temperatures (150 ^oC and 210 ^oC for 2 h and 8 h). Physical properties such as swelling, water absorption and density and mechanical properties like modulus of elasticity, modulus of rupture, impact bending, compression strength and Brinell hardness of tin alloy thermal modified and control samples were evaluated. The results showed that tin alloy thermal modification decreased the swelling of the wood to 4,85 %, 1,45 % and 6,99 % along the tangential, radial and volumetric coefficient and water absorption and density decreased to 53,10 % and 290 kg/m³ respectively compared to the control. Modulus of elasticity, modulus of rupture, impact bending, compression strength and Brinell hardness of tin alloy thermal modified F. simplex at 210 °C for 8 h decreased to 6366,1 MPa, 54,9 MPa, 2,7 MPa, 29,4 MPa and 1113,5 MPa respectively compared to the control. In conclusion, the tin alloy thermal modified wood at 210 ^oC significantly affected the physical and mechanical properties of the wood.