Ormancılık Bölümü

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https://hdl.handle.net/20.500.12491/10820

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Eco-friendly particleboards with low formaldehyde emission and enhanced mechanical properties produced with foamed urea-formaldehyde resins
(Elsevier Science Ltd, 2022) Kelleci, Orhan; Köksal, Süheyla Esin; Aydemir, Deniz; Sancar, Semih
Urea formaldehyde (UF) is the most widely used thermoset glue in the wood composite board industry. UF has formaldehyde emission, which is harmful to the environment and human health. In this study, it was aimed to ensure more efficient use of glue by foaming UF, as well as to reduce the amount of formaldehyde emission and thus to realize a cleaner production. In the UF resin foaming process, egg white (EW) and blood flour (BF) were used as foaming agents, which increased the resin volume by 4-7 times. Ammonium sulfate (AS) was used as a hardener for the UF. The UF resin and AS solid concentrations were 65% and 30%, respectively. The resins used in the production were prepared by blending UF, AS, and blowing agents using a mixer at 1000 rpm. The resin was then sprayed onto the surface of the wood chips via an air gun under 5 bar pressure. The PBs were produced as a monolayer from only a core layer (CL) of wood chips. The obtained PBs were characterized by their physical and mechanical properties and formaldehyde emissions. The morphological characterization of the foamed resins was also examined. The results showed that the foaming process had improved the mechanical properties of the PBs by about 30%; however, no significant differences were found in the physical properties of the PBs. Morphological characterization showed that the UF foaming with blow agents had proved to be successful and the resin volume had been increased 4-7 times by the foaming. Formaldehyde emissions were found to be lower (2.5-5.1 mg/100 g) than for the un-foamed resins (3.95-7.31 mg/100 g). It was concluded that PBs with good mechanical properties and low formaldehyde emission can be manufactured by using 30% less UF resin.
Application of acrylic-based varnishes reinforced with nano fillers for conservation of weathered and worn surfaces of the historical and cultural wooden buildings
(Elsevier France-Editions Scientifiques Medicales Elsevier, 2022) Aksu, Soner; Kelleci, Orhan; Aydemir, Deniz; İstek, Abdullah
The aim of this study was to investigate the surface protection effects of acrylic-based varnishes including TiO2 and Al2O3 nano-fillers in the conservation process of naturally aged and worn surfaces of historical and cultural wooden structures. The varnishes were applied to the wood surfaces with a brush and the varnish-coated samples were artificially aged in a weathering cabin. The changes in the surfaces of the samples were evaluated according to color change, micro hardness, abrasion tests, scratch tests, surface durability, and surface characterization via scanning electron microscopy (SEM). The thermal properties and morphological characterization of the varnishes with nano-fillers were also determined, and ultraviolet-visible (UV-vis) and FTIR analyses were performed. The results showed that the micro hardness, abrasion, and scratch values of the varnishes were not statistically significant. However, the values of the varnishes with TiO2 were determined to be slightly higher than those of the varnishes with Al2O3. The surface durability of the neat varnish was significantly improved by adding the nano-fillers. With the addition of the nano-fillers, the SEM revealed reduced thickness of the varnishes on the surfaces of the wood samples. The thermal properties, optical properties with UV-vis, and morphological structure of the neat varnish were improved by adding the nano-fillers, whereas the FTIR detected no difference in the bonding of the varnishes. The UV spectra of TiO2 and Al2O3 generally showed a peak at 354nm and 210nm wavelengths, which means that they exhibited good absorbance in the UV region. The results indicated that adding nano-fillers to the neat varnish could generally improve the outdoor performance and lifetime of historical and cultural wooden structures. (C) 2022 Elsevier Masson SAS. All rights reserved.
Wood flour-reinforced green composites: Parameter optimization via multi-criteria decision-making methods
(Springer, 2022) Kelleci, Orhan; Aydemir, Deniz; Altuntaş, Ertuğrul; Kurt, Rıfat; Öztel, Ahmet; Yörür, Hüseyin
The aim of this study was to investigate the physical, mechanical, morphological, structural, and thermal properties of polylactic acid (PLA) and polyhydroxybutyrate (PHB) biopolymer composites reinforced with thermally treated wood flour and to determine the formulations having optimum properties by using multi-criteria decision-making (MCDM) methods. As a filler, Scots pine wood flour (untreated and thermally treated at 212 degrees C) was used at the loading rates of 10% and 30%. The samples were prepared using a twin-screw extruder and then by compression molding. The results showed that the addition of both thermally treated and untreated wood flour slightly increased the density of the composites. According to the color measurement, the thermally treated wood composites were slightly darkened in appearance. In the composites, with both wood fillers, the water absorption and thickness swelling ratios had increased during the 20-250 days of water exposure. Lower water absorption and thickness swelling rates were found for the composites with thermally treated wood filler compared to the other composites. The wood fillers generally lowered the mechanical properties of the PLA and PLA/PHB composites, with the PHB composites as the exception. However, the tensile modulus and Izod impact strength of the composites generally increased with the addition of wood fillers. Morphological examination performed by scanning electron microscopy (SEM) indicated that the wood flour was mostly homogeneously distributed in the matrix, which improved the mechanical properties of the composites. Thermogravimetric analysis (TGA) showed that the addition of wood filler to the neat biopolymers as a rule did not provide significant improvement in the thermal stability; however, the fillers increased the thermal stability of neat PHB. The Fourier-transform infrared (FTIR) spectroscopy detected no differences in the chemical structure of the composites. The X-ray diffraction (XRD) results indicated a general increase in the crystallinity with the addition of wood fillers to the neat biopolymers and the blends. All the findings were subjected to MCDM analysis to determine the formulation having the optimum properties and the results showed this to be the neat PLA sample.
Thermoplastic composites of polypropylene/biopolymer blends and wood flour: Parameter optimization with fuzzy-grey relational analysis
(SAGE Publications Ltd, 2022) Kelleci, Orhan; Aydemir, Deniz; Altuntaş, Ertuğrul; Kurt, Rıfat; Yörür, Hüseyin
In this study, blends of polypropylene (PP) with polylactic acid (PLA) and polyhydroxybutyrate (PHB) biopolymers and wood flour were prepared, and Fuzzy and Grey Multi-Criteria Decision-Making (MCDM) methods were used to determine the blends with the best properties. The physical, mechanical, thermal, structural, and morphological properties of the composites were determined. The obtained results showed that PLA and wood flour generally improved the mechanical properties of the PP composites. However, wood flour did not exhibit a homogeneous distribution in the matrix. The density of the composites generally increased with the addition of both PLA and PHB. X-ray diffraction analysis showed that the crystallinity index of the composites generally decreased due to the low crystallinity of biopolymers. Thermal stability did not change with the addition of PLA and PHB, but the addition of wood increased thermal stability. According to the MCDM analysis, both Fuzzy and Grey results were similar.
Installation of test setup and measurement procedures in fir wood hydraulic conductance measurement
(Zagreb Univ, Fac Forestry, 2021) Köksal, Süheyla Esin; Gündüz, Gökhan; Kalkat, Menderes
For a hydraulic conductor, through which liquid flows, hydraulic conductance (K, ml.s(-1).MPa-1) is defined as the ratio of pressure difference at the inlet and outlet to the fluid amount passing through the hydraulic conductor in a unit time period. This property is one of the key functions of the wood, and is obtained by the flow rate (F - Flow, ml.s(-1)) along the wood sample divided by the pressure difference driving the flow (Delta P MPa). This study aimed to establish a test setup to determine the hydraulic conductance values of Uludag Fir (Abies bornmulleriana Hattf). A test setup was established to measure the amount of water that flows in samples and pressure difference in characterized capillary tubes. In addition, calibration of the test apparatus is explained in detail. Fir wood samples taken from Yedigoller, which is affiliated to Kale Operation Chieftainship and Bolu Forest Regional Directorate, of 4 mm in diameter and 3 cm in length were prepared and hydraulic conductance measurements were performed, and the results are presented in this article. The installed test setup was used to obtain the following information about frees: operation of the hydraulic conduction system, the amount of needed water, seasonal effects and stress-related changes.
Farklı ilgi gruplarının milli park algıları üzerine bir değerlendirme: Küre Dağları Milli Parkı örneği
(2015) Akbulut, Gül; Atmiş, Erdoğan; Günşen, H. Batuhan
İlgi gruplarının katılımı konusu diğer alanlarda olduğu gibi korunan alanların yönetiminde de önem kazanmaktadır. Her bir ilgi grubunun korunan alanlardan beklentileri farklı olabilmektedir. Korunan alan yönetimleri bu farklı beklentileri dengeli bir şekilde park yönetimine yansıtamadığı takdirde doğal kaynaklar üzerinde geri dönüşü olmayan zararlar meydana gelebilmektedir. İlgi gruplarının çevrelerindeki doğal kaynaklara olan ilgisi ve bu kaynaklar hakkındaki bilgi düzeyi onların doğal kaynakların planlanma ve yönetimi sürecindeki katılımlarının derecesini de etkilemektedir. Bu çalışma Küre Dağları Milli Parkı’nı sınırları içinde bulunduran iki ilden biri olan Bartın ilinde yapılmıştır. Çalışmanın amacı; ilde bulunan dört farklı ilgi grubunun Küre Dağları Milli Parkı ile ilgili düşüncelerini tespit etmek ve bu görüşler doğrultusunda park yönetimine yol gösterecek öneriler ortaya koymaktır. Bu gruplar; kamu yöneticileri, özel sektör, sivil toplum örgütleri ve muhtarlardır. Her bir grup için farklı anketler hazırlanmıştır. İlgi gruplarıyla yapılan görüşmeler ve uygulanan anketler sonucunda; bu grupların milli park yönetimi, milli parktan beklentileri, PAN Parks süreci, getirilen kısıtlamalar, sağlanan yasal haklar ve alternatif gelir kaynakları hakkındaki düşünceleri öğrenilmiş, dört farklı ilgi grubunun bu konulara yaklaşımları arasındaki fark ve benzerlikler sorgulanmıştır. Bulgulara göre; milli parkın kuruluşundan en düşük düzeyde memnun olan ilgi grubu muhtarlardır. Görüşülen kişilerin çoğunluğu milli parkın Bartın’da yaşayanların ilgisini çekmediğini ve Küre Dağları Milli Parkı’nın hem yerel halka hem de ülke geneline tanıtımında başarılı olunamadığını belirtmiştir. Çalışmada ayrıca bu bulgular yorumlanarak, 2012 yılı Mayıs ayında PAN Parks sistemine dahil olan Küre Dağları Milli Parkı yönetimine yol gösterecek öneriler geliştirilmiştir.

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