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Öğe Investigation of some mechanical and physical properties of boards produced from chips modified with vinyltrimethoxysilane([TR] Orman Genel Müdürlüğü, 2022) Gönültaş, Oktay; Ermeydan, Mahmut Ali; Aykanat, OnurWood surface modification is a comprehensive concept that has proven successful in increasing the resistance of wood throughout its lifecycle in both indoor and outdoor applications. In this study, it is aimed to chemically modify the chips in order to reduce the emission of formaldehyde used in particle board production and to observe the changes in the mechanical and physical properties of the boards. The particle boards were produced using 7% urea-formaldehyde in the middle layers and 12% in the surface layers, a press temperature of 190°C and a pressing time of 4 minutes. Samples were prepared from each group, and physical properties such as density, water absorption, and thickness swelling and mechanical properties such as bending resistance, the flexural modulus of elasticity, and tensile strength perpendicular to the surface were determined in accordance with the standards. In addition, Fourier Transform Infrared Spectroscopy (FTIR) analysis was applied to determine the chemical properties of the chemically modified chips, and Thermogravimetric Analysis (TGA) was applied to determine their thermal properties. Thus, the effects of using chemically surface modified chips in particle board production on board quality were investigated.Öğe Türkiye’de Fıstık çamı (Pinus pinea) İbresi Uçucu Yağının Coğrafi Varyasyonu(Kastamonu Üniversitesi, 2022) Uçar, Mualla Balaban; Gönültaş, OktayÇalışmanın amacı: Türkiye’de beş lokasyondan elde edilen Pinus pinea ibre uçucu yağlarının kimyasal bileşimi tür içi varyasyonlarını belirlemektir. Çalışma alanı: Bölgeler arası farklılıkları belirlemek için Türkiye’deki beş lokasyondan (Doğu-Çoruh, Kahramanmaraş-Kapıçam, Kahramanmaraş-Önsen, Batı-Armutlu ve Kozak) Pinus pinea taze ibre örnekleri toplanmıştır. Materyal ve yöntem: Her bir numune grubu için taze ibre örnekleri (700-800 g) 3 litre suda 2 saat boyunca hidrodestilasyon yöntemiyle işlendi. Uçucu yağlardaki bileşikleri belirlemek ve ölçmek için GC-MS cihazında analizler yapıldı. Temel sonuçlar: İbre uçucu yağında monoterpen hidrokarbonların (% 69.00-84.90), seskiterpenlerin (% 4.10-8.80) ve diterpenlerin (% 1.02-1.57) baskın olarak bulunduğu görüldü. Sonuçlardan incelendiğinde, uçucu yağ esas olarak limonen (%52.70-76.10), ?-phellandrene (%3.19-7.20), ?-terpineol (% 1.46-9.88), ?-karyofillen (%1.55-3.26) ve germakren D'den (0.67-%2.43) oluşmaktadır. Türkiye'den elde edilen uçucu yağın İtalya ve Cezayir'e benzer şekilde %50'den fazla limonen içeriğine sahip olduğu bu oranın Yunanistan ve Tunus'tan elde edilenlerde daha düşüktür. Araştırma vurguları: Kümeleme analizi ile üç gruba ayrılmasını sağlamıştır. Birinci grup doğu meşcereleri olan Çoruh ve Kahramanmaraş Kapıcam olmak üzere daha yüksek limonen ve daha düşük miktarda ?-karyofillen içeren şeklinde tanımlanırken diğer grup ise batı bölgeleri Armutlu ve Kozak, daha düşük miktarlarda limonen ve daha yüksek miktarda ?-terpineol ile tanımlanmıştır.Öğe Utilization of bark tannins from oriental spruce and oak in bioadhesive production(Isparta Uygulamalı Bilimler Üniversitesi, 2019) Gönültaş, Oktay; Uçar, MuallaIn this research, bio-based tannin adhesives were developed by using tannins from spruce (Picea orientalis) and oak (Quercus spp.). The barks were obtained from wood-based panel industry and forest residues. The tannin powders were produced with a spray dryer based on the observations during the extraction process. Chemical analyzes were performed to determine the phenolic content of the spruce and oak tannins. After that bioadhesive synthesis experimentals were carried out using the spruce and oak tannins. In the experimentals, the bioadhesive synthesis parameters such as pH, formaldehyde:tannin molar ratio, viscosity, and free formaldehyde content were optimized. Finally, the adhesion performances of the bioadhesives were determined with the lap shear test. The results obtained in this work clearly showed that the shelf life and free formaldehyde content values of the adhesives were affected by the formaldehyde:tannin molar ratios. As for the maximum shelf life values of the bioadhesives, the spruce tannin adhesive had 72 days shelf life, whereas the oak tannin adhesive had 38 days. The gelation time values related with pH were also examined. The findings demonstrated that the spruce and oak sulfited tannins had 12% higher gelation time values than those of the water tannins. According to the results of the lap shear test, the spruce tannin based bioadhesives had similar adhesion performance as compared with a commercial phenol formaldehyde adhesive.Öğe Başlıksız(North Carolina State Univ Dept Wood & Paper Sci, 2018) Gönültaş, OktayTannin-based adhesives are alternative bio-based products that can be used in the wood panel industry instead of synthetic adhesives that contain formaldehyde. For the production of these adhesives, formaldehyde is utilized generally as a hardener as in its synthetic counterparts. In this study, adhesive formulations were prepared using eight different hardeners and tannin powder from Turkish red pine (Pinus brutia) barks. While the shortest gel time values in the adhesive formulations were identified in the samples prepared with formaldehyde and paraformaldehyde, the longest gel time was obtained in the formulation prepared with tris(hydroxymethyl)nitromethane. As a result of the dry bonding tests, the values closest to the commercial UF adhesive were found in descending order as paraformaldehyde, formaldehyde, hexamine glyoxal, and poly[(phenyl isocyanate)-co-formaldehyde] (pMDI). According to the wet bonding strength test results, the adhesive samples in which furfural, tris(hydroxymethyl)nitromethane, and benzaldehyde were used as hardeners did not achieve wet bonding strength. As a result of thermogravimetric analysis (TGA), commercial UF adhesive samples had dramatically lower thermal stability than all of the formulations prepared with tannin. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectral analysis revealed that new chemical bonds were established between the tannin and hardeners.Öğe Başlıksız(Springer, 2019) Balaban-Ucar, M.; Gönültaş, OktayVolatile constituents from waterlogged cypress wood were investigated by means of GC-MS to examine the alteration of terpenoids during anaerobic conditions. The results were evaluated by comparison with the terpenoid composition of recent cypress wood Cupressus sempervirens. The essential oils contained largely monoterpenoids (carvacrol, carvacrol methyl ether, p-cymene), sesquiterpenoids (-cedrol, cedrene) and a diterpenoid (manool). The terpenoid characteristics strongly supported the relationship to the C. sempervirens wood. While sesquiterpenoids, i.e. -cedrol, remained almost intact in archaeological wood, in particular monoterpenoids but also the diterpenoid underwent considerable alteration. The same compounds in archaeological- and extant woods allow the conclusion that the diagenetic transformations took place in monoterpenoid moiety in waterlogged wood. A novel degradation of carvacrol methyl ether and carvacrol was detected, and an alteration pathway was suggested in this study. Sesquiterpenoids were detected in higher amounts as unaltered forms in archaeological samples, and it was shown that these compounds were very resistant and stable. Moreover, because of a remarkable decrease in its amount, the diterpenoid manool experienced degradation or chemical changes in archeological samples. It can be concluded that alteration of Cupressus wood compounds probably occurred under waterlogged anaerobic conditions leading to reductive reactions, demethylation and dehydroxlylation of monoterpenoids forming monoterpene- and aromatic compounds. The volatile constituents of archeological wood can serve as valuable chemo-systematic markers for waterlogged archaeological softwoods adequately buried in an anaerobic environment.Öğe Başlıksız(North Carolina State Univ Dept Wood & Paper Sci, 2018) Avci, Erkan; Acar, Mehmet; Gönültaş, Oktay; Candan, ZekiBark as a biowaste has a huge availability throughout the world and has had limited use in industrial applications. Black pine bark and oak bark were considered in this work. The aim was to manufacture a new biocomposite with different combination of black pine bark, oak bark, polypropylene, polyethylene, and a coupling agent, and to determine some physical and mechanical properties of the manufactured biocomposites. Density, thickness swelling, water absorption, tension strength, modulus of rapture and modulus of elasticity in bending and tension of the biocomposites were determined. According to the results, thickness swelling and water absorption properties were improved up to 80% when compared with wood-plastic composites (WPC) produced with wood flour. Although the new biocomposites displayed lower mechanical performance in comparison of biocomposites made with wood flour, the observed results were satisfactory. Based on the results of this study, black pine bark and oak bark can be used as filler materials in WPCs production. Hereby, these bark materials can be the raw material for value-added products. Bark use in biocomposite production also can contribute to reduced requirements of wood material and petroleum products.Öğe Başlıksız(Elsevier Sci Ltd, 2018) Dizman Tomak, Eylem; Arican, Ferhat; Gönültaş, Oktay; Parmak, Ebru D. SamThe aim of this study was to improve weathering resistance of Scots pine wood by treating the surfaces with water based transparent and opaque wood coatings containing valex, mimosa and pine tannins. Samples coated with tannin containing coatings with various concentrations were exposed to artificial weathering for 1512 h. Color, gloss, surface roughness and macroscopic changes were evaluated periodically during the test, and the results of coated samples were compared with controls. Visible surface degradations such as erosion, cracks and checks occurred on control samples while no crack formations were recorded for coated samples. Color measurement data showed that high concentration levels were needed for the least color change on the surfaces however concentration increase of tannins in the transparent coating affected surface gloss and roughness of samples negatively. The most promising tannin types in transparent coatings against the surface degradations were determined as valex and pine tannins. Opaque coating alone was found to be resistant against weathering factors, and the measurements clearly showed that there is no need to corporate any UV absorbers to this coating. (C) 2018 Elsevier Ltd. All rights reserved.Öğe Başlıksız(2017) Gönültaş, Oktay; Uçar, Mualla BalabanBu çalışmada, orman işletmelerinde kesim sonrası ortaya çıkan doğu ladini (Picea orientalis) kabukları ve ahşap levha endüstrisinde levha üretimi sonrası ortaya çıkan endüstriyel atık meşe (Qercus spp.) kabuklarının kimyasal bileşimi temel odun analizleri ve fenolik bileşik analiz metotlarıyla incelenmiştir. Kabuklarda kül tayini sonuçlarına göre Artvin ve Trabzon ladin örneklerinde % 4.31 ve % 3.99 kül bulunurken meşe kabuğunda % 10.02 gibi yüksek sonuç belirlenmiştir. Sıcak su çözünürlüğünün ladin örneklerinde meşeye göre daha yüksek olduğu ortaya konulmuştur. Artvin ladin, Trabzon ladin ve meşe kabuklarında kalıntı lignin sırasıyla % 19.53; % 20.61 ve % 18.49 olarak belirlenirken ?-selüloz miktarı için % 37.28; % 37.92 ve % 41.59 değerleri elde edilmiştir. Toplam fenol tayini ve butanol HCl yöntemi sonuçlarına göre Artvin ladin kabuğu en yüksek değerlere sahiptir. Ladin ve meşe kabuğu örneklerinde hidrolize tanenler olan gallo tanen bulunurken ellag taneni içeriği belirlenememiştirÖğe Başlıksız(2017) Gönültaş, Oktay; Sarıalan, NurÇalışmanın amacı: Bu çalışma kapsamında ülkemizde doğal olarak yetişen Toros sediri (Cedrus libani A. Rich.) ağaçlarının üretim kesimi sonucunda ortaya çıkan atık kabuklarından tanen ekstraksiyonu gerçekleştirilmiştir. Sedir kabuk taneni fenolik bileşimi analitik yöntemler ve FTIR analizi ile ortaya konulmuştur. Çalışma alanı: Atık ağaç kabuklarından tanen eldesi, ekstraktın fenolik bileşik karakterizasyonu ve endüstriyel kullanım olanaklarının belirlenmesidir. Materyal ve Yöntem: Adana bölgesinden temin edilen sedir kabuğu örnekleri, 1:8 kabuk çözücü oranında, 70°C'de 1 saat sıcak suda ekstrakte edilmiştir. Ekstrakt çözeltilerinde verim, pH ve stiasny sayısı değerleri belirlenmiştir. Ardından elde edilen tanenin fenolik bileşimi toplam fenol tayini, bütanol:HCl yöntemi, DNS indirgen şeker tayini ve FTIR analizi ile incelenmiştir. Sonuçlar: Ekstraksiyon sonucunda % 8.99 verim ve 28.85 stiasny sayısı değeri belirlenmiştir. Toplam fenol tayinini sonuçlarına göre eter fazı 15.02 mg/g ve su fazı 27.77 mg/g; bütanol HCl yöntemiyle 7.61 mg/g proantosiyanidin ve DNS indirgen şeker tayini sonucunda 41.77 mg/g değerleri elde edilmiştir. Tanen örneğinin FTIR spektrumu incelendiğinde kondanse tanenler için karakteristik 1605 cm-1 piki görülmektedir. Araştırma vurguları: Fenolik bileşik analiz metotları ve FTIR analizi ile toros sediri kabuk taneninin kondanse tanen yapıtaşı monomerik flavonoid birimleri içerdiği ortaya konulmuşturÖğe Başlıksız(2019) Parlak, Salih; Gönültaş, Oktay; Hamurcu, HarunGeleneksel halk hekimliğinde Ihlamur türleri (Tilia sp.)’nin tıbbi amaçlı kullanımı yüzyıllardır bilinmektedir. Kış mevsiminin en çok tüketilen bitki çaylarından biridir.Üretimin büyük bir kısmı Bursa ve Yalova İllerindeki doğal gümüşi ıhlamur (Tilia tomentosa Moench.) ormanlarından temin edilmektedir. Çiçek üretimi amacıyla kurulmuş plantasyonlar bulunmadığından, doğal ormanlardan yapılan üretim aşırı tahripkar olmaktadır. Bu tahribatın önüne geçilebilmesi için mutlaka çiçek verimi ve kalitesi yüksek bireyler seçilip klonal yolla çoğaltılarak çiçek üretimine yönelik plantasyonların kurulması gerekmektedir. Doğal popülasyonlarda çiçeklenme zamanı, çiçek rengi, iriliği, kokusu vb. unsurların değişkenlik arz ettiği görülmektedir. Bu çalışmada Bursa-Gökçeören, Karacabey-Yeniköy ve Yalova-Esenköy’deki doğal popülasyonlardan tam çiçeklenme zamanında toplanan örneklerin yağ miktarları Clevenger cihazı ile belirlenmiştir. Yağ verimine de etkili olabilecek mevki, rakım, bakı, eğim, taç yönü, çiçek rengi gibi faktörler incelenmiştir. Yağ miktarları ile fizyografik faktörler arasındaki ilişkiler irdelenmiştir. Yapılan çalışma sonucunda; ıhlamur çiçeklerinin yağ veriminin yörelere ve rakıma göre değişiklik gösterdiği, eğim ve bakının ise etkisinin olmadığı belirlenmiştir. Kapalılık, ağaç taç çapı, çiçek toplanan taç yönü, çiçek rengi, tomurcuk ve çiçeklenme durumlarının yağ verimini etkilemediği belirlenmiştir.Öğe Başlıksız(ICE Publishing, 2021) Yildirim M.; Candan Z.; Gönültaş, OktayUrea-formaldehyde (UF) resin is the most important used adhesive in the production of wood-based composite panels, such as particleboard, medium-density fiberboard, oriented strand board and plywood. The aim of this work was to investigate the influence of nanocellulose, boric acid and borax on the chemical performance properties of UF resin. UF resin was reinforced with various loading levels of nanocellulose, boric acid and borax. Formaldehyde emission, gel time, solid content, viscosity, pH, specific gravity, shelf life and Fourier transform infrared spectra were evaluated as indicators of chemical performance. The findings showed that the formaldehyde emission of hybrid UF resin reinforced with nanocellulose/boron compounds decreased by up to 31.25%. The use of the reinforcement technique in the resin caused an increase in shelf life, viscosity and gel time but caused a reduction in the solid content of the resin. The apparent specific gravity of the resin was not influenced by the addition of nanocellulose/boron compounds. It was concluded that the chemical performance properties of UF resin could be enhanced by using proper nanocellulose, boric acid and borax loading levels. By using the reinforcement technique, it was possible to produce low-formaldehyde-emitting adhesives so that environmentally friendly products could be manufactured.Öğe Başlıksız(2021) Candan Z.; Gönültaş, Oktay; Gorgun H.V.; Unsal O.The aim of this study was to evaluate the effect of thermal compression process on some surface properties of paulownia solid wood materials. The widest surface of wood samples was mechanically compressed at high temperatures. The duration was 45 min. Four different process combinations were created, including two temperatures (150 °C and 170 °C) and two pressure levels (20 bar and 22.5 bar). The surface roughness, wettability and color properties of treated and untreated samples were compared. The roughness properties, both parallel and perpendicular to grain direction, were determined according to JIS B 0601:1994 standard. The contact angle changes of water dripped to the surface were measured according to time. For color properties, a spectrophotometer was used according to CIE L*a*b* system. The color changes were classified according to a grading method from literature. The most remarkable results on wettability were observed. The contact angle values significantly increased with this method. Although higher temperature increased the contact angle values, higher pressures did not change the values. When the surface roughness values were generally considered, this technique could decrease the values up to 40 % ratio according to the control group. Only the combination of 150 °C and 20 bar did not significantly change the values. Lastly, the results of color properties showed that all treatment parameters significantly affected total color change values of samples. Grading results were similar and the color change of modified samples graded as the lowest color difference, except with the combination of 150 °C and 20 bar. The combination of 170 °C and 22.5 bar (highest treatment conditions) significantly changed all color characteristics of samples, except b* parameter. The results of this research showed that mechanical thermal compression method could change surface properties of this fast-growing speciesÖğe Başlıksız(Univ Bio-Bio, 2018) Gönültaş, Oktay; Candan, ZekiIn this study, the change in the chemical properties of the thermally modified eucalyptus (Eucalyptus camaldulensis) wood boards were examined by wet chemical analysis and FTIR spectroscopy. The eucalyptus wood boards were modified with a laboratory type hot-press for four different groups at press pressures of 2 or 4 MPa and temperatures of 150 degrees C or 180 degrees C and compared to untreated control. After this, hot water, 1% NaOH, ethanol-cyclohexane, ethanol, and methanol-water solubility values were determined for the treated samples. In addition, the content of klason lignin, acid soluble lignin, holocellulose, and alpha-cellulose were investigated. The solubility values (except for the ethanol solubility) increased in the modified wood when compared to the untreated control. A decrease in the content of acid soluble lignin, holocellulose and alpha-cellulose was observed while the content of klason lignin in the modified wood was increased. According to the FTIR analysis results, significant changes were observed in the spectra of the modified samples. These findings were in agreement with the results of wet chemical analysis.Öğe Başlıksız(Taylor & Francis Inc, 2018) Dizman Tomak, Eylem; Gönültaş, OktayThis study investigated antifungal properties of four different tannins as potential environmentally friendly wood preservatives. Scots pine wood samples were impregnated with 3, 5, 10, and 15% valonia, chestnut, tara, and sulphited oak tannins, and then were exposed to brown rot fungi Coniophora puteana and Postia placenta, and white rot fungi Trametes versicolor and Pleurotus ostreatus attack to determine the best tannin type and the optimum concentration level for sufficient decay resistance. Leaching test was conducted in order to evaluate any loss in effectiveness in decay resistance due to possibility of tannin leaching. Tannins were found efficacious in suppressing brown rot fungi attacks when no leaching prior the decay test was used, however, they seemed to be ineffective against white rot fungi attacks. The lowest weight losses were obtained with valonia and chestnut tannins both for brown and white rot fungi probable related with their high ellagic tannin content.Öğe Başlıksız(Elsevier Sci Ltd, 2018) Dizman Tomak, Eylem; Yazici, Omur A.; Şam Parmak, Ebru Devrim; Gönültaş, OktayIn this study, influence of tannin containing coating combined with zinc and cerium oxide nanoparticles on color, gloss, surface roughness and macroscopic changes of Scots pine wood after artificial weathering was studied. For this purpose, 3 different tannin types, valex, mimosa and pine with various concentrations, 2 metal oxides, nano zinc and cerium oxide, and a water based transparent coating were used. Commercially available nano wood coating was used as a reference chemical. Results showed that wood surfaces got dark color, lost the initial gloss and become rougher after weathering of 1512h. Samples coated with tannin and nano metal oxide containing coatings exhibited better protection against degradation factors than reference and controls. Among the treatments, low concentration levels of tannins and cerium oxide were found to be more efficient on protection of wood surfaces in comparison to high concentration levels and zinc oxide. General condition of samples seemed to be better for mimosa and pine tannins for ZnO combinations, and valex and pine tannins for CeO2 combinations after the weathering test. Results of such a combination system clearly showed amount of expensive inorganic nanoparticles could be reduced with the addition of natural antioxidants into transparent coatings. (C) 2018 Elsevier Ltd. All rights reserved.
