Browsing by Author "Ayata, Ümit"
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- Effect of heat treatment on shore-D hardness of some wood speciesPublication . Esteves, Bruno; Sahin, Sirri; Ayata, Ümit; Domingos, Idalina; Ferreira, José; Gürleyen, LeventHardness is an important wood property for several applications. Typically, it is necessary to use traditional methods, such as a universal test machine, to determine a wood’s hardness value. This work reports the hardness of some wood species before and after heat treatment (ThermoWood method) using the Shore-D hardness method. The Shore- D hardness value of untreated wood ranged between 35.3 for Limba wood and 77.2 for Santos wood. With heat treatment, hardness decreased, and the decrease was greater for samples that underwent harsher treatment (2 h at 212 °C). The decrease of hardness was highest for Sipo wood (14%) and the lowest for Afrormosia wood (2.5%). Analysis of variance tests showed that there was a significant difference between wood species, heat treatment, and the interaction between both variables at the chosen level of significance (P ≤ 0.05). Results showed that Shore-D hardness could be used to measure hardness directly in a production line or in small wood companies without using a universal test machine.
- Effects of artificial weathering on the surface properties of coated radiata pinePublication . Sahin, Sirri; Esteves, Bruno; Can, Ahmet; Sivrikaya, Hüseyin; Domingos, Idalina; Ferreira, José; Ayata, ÜmitRadiata pine boards were coated with two different methods A and B both beginning with a hydro primer and finishing with a mat oil but method A using an acrylic high gloss coating and method B three layers of an acrylic sealer in between. The samples were subjected to aging processes for 144 h, 288 h, and 432 h by using UV-A 340 nm lamps. The CIE L*a*b* and CIE L*C*H* coordinates were determined (L*, a*, b*, C*, ho *, ΔE*), gloss (perpendicular ( ) and parallel (//) to the grain at 20°, 60°, and 85° angles) and surface adhesion strength via the pull-off method were tested before and after weathering. Results have shown that lightness (L*), decreases with weathering for both varnish applications with a higher decrease for the B coating system. Redness increased for both applications with no significant differences. At the same time there was a yellowing of the samples along the weathering period. Parallel and perpendicular gloss decreased for 20º and 60º angles while it increased for 85º angle. The adhesion strength of method A was higher and its decrease with weathering was smaller than for method B. Both varnish applications have proven to confer some protection against wood discoloration, but method A showed the best results and is therefore the best method to be used by radiata pine.
- Investigation of Use of Linden (Tilia tomentosa Moench.) Wood with UV System Varnish Application IN INDOOR Parquet FlooringPublication . Ayata, Ümit; Esteves, Bruno; Domingos, Idalina; Ferreira, José; Efe, Fatih Tuncay; Türk, Mutlu; Çakicier, Nevzat; Gürleyen, Levent; Peker, HüseyinLinden wood is used in the making of musical instruments, agricultural hand tools, and in the furniture sector. In this study, the changes in glossiness (parallel (//) and perpendicular (⊥) to the fibers at 20o , 60o , and 85o), the pull-off adhesion test, color parameters (CIEL) and pendulum hardness (König method) of two different UV curable varnishes applied to linden (Tilia tomentosa Moench.) according to industrial application techniques and exposed to artificial weathering were investigated. According to the research results, while L*, ΔH*, and ho decreased with increasing weathering time in both varnish layers, ΔC*, b*, ΔE*, a*, and C* rose. The pendulum hardness grew for Method B but dwindled for Method A. A decrease was found in the adhesion tests for both varnish methods after artificial weathering. The glossiness was generally reduced due to artificial weathering for all the angles and for both directions, with the exception of 85º in Method A. The variance analysis and homogeneity groups showed that the changes in the adhesion, pendulum hardness, L*, a*, ho , C*, perpendicular and parallel to the fibers for 60o and 85o were found to be significantly different with artificial weathering for both methods.
- Testing of waste vegetable oils as color modifiers in American walnut (Juglans nigra L.) woodPublication . Peker, Hüseyin; Esteves, Bruno; Ayata, ÜmitAmerican walnut (Juglans nigra L.) wood is used for veneer due to its beautifully grained and dark-colored wood. This study was conducted to test the use of plant waste oils as color modifiers on American walnut wood. As waste vegetable oils, discarded walnut, olive, corn, and sunflower oils were employed. After applying waste oils to the wooden surfaces, several surface properties (brightness, color, and whiteness index: WI*) were determined. It was observed that multivariate analysis of variance tests conducted for WI* values and color parameters were found to be statistically significant. For all vegetable waste oils, decreases were identified in L*, C*, h o , and b* parameters, as well as in WI* values and glossiness values (for all degrees and orientations). The ∆E* values were measured at 19.18 for sunflower, 22.02 for walnut, 22.65 for corn, and 19.49 for olive. Each of the discarded vegetable oils had an impact on the color of the wooden surface.
- The effects of thermal aging on color and glossiness in UV cured coatings applied to sessile oakPublication . Sahin, Sirri; Ayata, Ümit; Esteves, BrunoColor 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*, ho) 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 ho. 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 ho and L* decreased. The characteristics of the surfaces exposed to thermal aging have undergone a complete transformation.