Yazar "Özbay, G." seçeneğine göre listele
Listeleniyor 1 - 5 / 5
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Adhesive bond performance of heat-treated wood at various conditions(Triveni Enterprises, 2016) Kol, H.S.; Özbay, G.Heat treatment of wood leads to chemical, structural and physical changes in wood constituents, which can significantly affect the bonding performance of wood in several ways depending on the adhesive type used. In the present study, fir (Abies bornmülleriana Mattf.) and beech (Fagus orientalis L.) were heat treated at 170°C, 180°C, 190°C, 200 and 212°C for 2 hours. Four different types of adhesives were used for bonding process: melamine-urea-formaldehyde (MUF), melamine formaldehyde (MF), phenol formaldehyde (PF), and polyurethane (PUR). For all the pretreatment conditions, highest shear strength of adhesive bonds of each adhesive system was observed for untreated samples and shear strength decreased with increasing heat treatment. The strength of each adhesive bond of samples which were soaked in water was much less than dry samples, approximately half of the dry strength. Generally, the shear strength of the adhesive bonds after boiling was smaller than or similar to the values obtained for soaking. The untreated samples lost more strength after soaking and boiling than heat treated samples. With increasing heat treatment severity, reduction in shear strength increased in dry samples while decreased in soaking and boiling samples. For instance, after soaking, the untreated samples lost more strength (almost 39%) than heat treated samples (almost 24% for most severely heat treated samples). The results showed that the shear strength of adhesive bonds was influenced by heat treatment and depended on pretreatment of samples prior to testing. In general, all adhesives used performed in quite a similar way for all pretreatment conditions, and the bonding performance of heat treated fir wood was less satisfactory than that of beech wood for all adhesive system and condition. © Triveni Enterprises.Öğe Bio-oil production from catalytic pyrolysis method of furniture industry sawdust(2013) Özçifçi, A.; Özbay, G.In this study, scots pine (Pinus sylvestris L.) sawdust was used as biomass resources. Catalyzed and uncatalyzed (thermal) pyrolysis processes were conducted in a fixed-bed reactor. The effects of the parameters on pyrolysis product yields such as temperature and catalysis type were investigated. The pyrolysis of the experimental samples that have a particle size in the range of 0.850-1.60 mm were carried out at the temperatures of 400, 500 and 600 °C at the heating rate of 5°C/min. Nitrogen gas (N2) flow was used at the rate of 30 ml/min during the process. Basic salts such as Na 2CO3, K2CO3 and Lewis acid (FeCl3) were used as catalyses. As a result, it was determined that temperature and catalysis types were effective parameters in the yields of char, bio-oil and gas products. Also it was determined that the conversion of wood materials into fuel or valuable chemicals with the pyrolysis method is an applicable technology.Öğe Impacts of bleaching chemicals and outdoor exposure on changes in the color of some varnished woods(2010) Özçifçi, A.; Özbay, G.This study was carried out to determine the changes of the surface color of Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis Lipsky) woods after exterior conditioning. First, the samples were bleached with 25% NaOH and 17.5% H2O2. Afterwards, they were varnished with polyurethane and synthetic varnishes, and then they were exposed to exterior conditions for 12 months. Tests for color differences and metric chroma were done according to the ASTM D-2244 standard. It was deduced that exposure to exterior conditions causes color differences in samples, while bleaching with the given solution reduces that effects, and reverts the surface color to that of the natural control specimens. However, bleached specimens exposed to 12 months exterior conditioning had more discoloration than those of natural control samples. In conclusion, if the wood materials will be exposed to outdoors after bleaching, finishing process should be applied to surfaces in order to prevent further color change.Öğe Shear strength of heat-treated tali (Erythrophleum ivorense) and iroko (Chlorophora excelsa) woods, bonded with various adhesives(2009) Kol, H.S.; Özbay, G.; Altun, S.The aim of this study was to evaluate the effect of heat treatment on the shear strength of tali (Erythrophleum ivorense) and iroko (Chlorophora excelsa) woods, bonded with some structural adhesives. Shear strength of untreated and heat-treated woods bonded with phenol-formaldehyde (PF), melamine-urea-formaldehyde (MUF), melamine-formaldehyde (MF), and polyurethane (PUR) adhesives was studied. An industrial heat treatment method (ThermoWood) was used. The timbers were thermally modified for 2 hours at 180 °C. Laminated samples having two sample sets were prepared from untreated and heat-treated wood for the shear strength test. The results of the tests showed that the heat treatment affected shear strength of laminated wood negatively. Although there was a considerable difference in adhesive bond shear strength between untreated and treated wood, both wood species bonded with the adhesives fulfilled the required value for shear strength of the adhesive bonds. PF, MUF, MF, and PUR adhesives performed in a rather similar way for both wood species.Öğe Synthesis and characterization of resol type phenol-formaldehyde resin improved by SiO2-Np(Pulp and Paper Research Institute, 2021) Özbay, G.; Kokten, E.S.; Ozcifci, A.In this work, resol type phenol-formaldehyde (RPF) resin was modified with silicon dioxide nanoparticles (SiO2-Np). SiO2-Np was added at varying ratios from 1 to 4 wt.% to improve the bonding performance of the RPF resins. The physical characteristics of the nano-modified RPF (nano-RPF) resins were examined. The effects of modification were studied by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The results of FT-IR revealed that the nano-RPF resins were successfully produced by phenol, formaldehyde, and SiO2-Np. The nano-RPF resins demonstrated high thermal stability at temperatures above 500°C. The adhesive performance of the nano-RPF resins was investigated under dry and wet conditions. The nano-RPF resins indicated better adhesive performance than unmodified RPF resin. The RPF resin could be improved by SiO2-Np. © 2021 Statny Drevarsky Vyskumny Ustav. All rights reserved.
