19 results on '"Thermogravimetric analysis"'
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2. Kanal Tedavisi Sonrasında Restoratif İşlemler için Yeni Nanokompozit Malzemelerin Üretilmesi ve Termal Analizlerinin Değerlendirilmesi.
- Author
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KAMALAK, Aliye
- Abstract
Copyright of Firat Universitesi Sağlik Bilimleri Tip Dergisi is the property of Firat Universitesiu, Saglik Bilimleri Enstitusu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2020
3. Thermal behavior of Liquidambar orientalis mill wood before and after extraction processes
- Author
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Evren Terzi
- Subjects
Wood extractives ,thermogravimetric analysis ,Liquidambar orientalis ,storax wood ,thermal degradation ,natural fire retardants ,Forestry ,SD1-669.5 - Abstract
The effect of extractives on the thermal behavior of Liquidambar orientalis Mill. (storax) wood is studied using thermogravimetric analysis (TGA). To evaluate the effects of polar and apolar extractives on the thermal behavior of wood, sawdust samples from the heartwood of L. orientalis are extracted with either cold water (48 h), hot water (48 h), or ethanol/toluene (1:2 v/v) (6 h) prior to thermal analysis. Thermogravimetry (TG) curves show that polar and apolar extractives promote char formation, increase the amount of residue, and improve the thermal behavior of L. orientalis wood. In addition, derivative thermogravimetry (DTG) curves demonstrate that thermal degradation of un-extracted and cold water-extracted wood samples occurs in a single step, while a two-step degradation pattern is seen for hot water- and ethanol/toluene-extracted wood samples. It is also observed that first degradation reactions in hot water and ethanol/toluene-extracted wood samples occur faster than those in unextracted and cold water-extracted wood samples. Although there are approximately half the number of extracted apolar compounds compared to polar compounds, the removal of both types of compounds affect the thermal properties of L. orientalis wood to the same degree. It is thus deduced that apolar extractives significantly affect the thermal behavior of L. orientalis wood.
- Published
- 2017
- Full Text
- View/download PDF
4. Determination of thermal, physical, optical and mechanical properties of waste papers prepared by adding Firetex
- Author
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PEŞMAN, Emrah and CİVİL, Ezgi
- Subjects
Atık kağıt ,Firetex ,termogravimetrik analiz ,limit oksijen indeksi ,Waste paper ,thermogravimetric analysis ,limited oxygen index ,Forestry ,Orman Mühendisliği - Abstract
Çalışmada hammadde olarak mekanik hamur bazlı teksir (gazete) kağıtları, yangın geciktirici olarak su bazlı Firetex (taş suyu) ticari ürünü kullanılmıştır. Teksir kağıtları çalışma öncesi hamurlaştırıcıda açılmış ve rapid-köthen makinesi ile tekrar kağıt haline dönüştürülmüştür. Firetex, kağıtlara daldırma yöntemi ile %25, %50, %75 ve %100 konsantrasyonlarda uygulanmıştır. Çalışma kapsamında üretilen test kağıtlarının termal, sağlamlık ve optik özellikleri ölçülmüş ve optimizasyonu gerçekleştirilmiştir. Çalışmada test örneklerinin termogravimetrik (TGA) analizleri sonucunda artırılan Firetex oranı ile kömürleşmenin ve kalıntı miktarının önemli ölçüde artış gösterdiği tespit edilmiştir. Örneklerin limit oksijen indeksi (LOI) değerlerinin de artırılan Firetex oranı ile arttığı, %50’lik konsantrasyon ile standart kabul edilen 26 LOI değerinin aşıldığı, %100 yangın geciktirici ile işlem gören örneklerde cihaz limitlerinin aşıldığı tespit edilmiştir. Artırılan Firetex oranı yanmaya karşı direnci geliştirirken kopma ve yırtılma direncini düşürdüğü tespit edilmiştir. Çalışma sonucunda LOI ve sağlamlık değerleri birlikte düşünüldüğünde atık gazete kağıtları için en uygun Firetex konsantrasyonu %50 olarak belirlenmiştir., In the study, mechanical pulp-based (newspaper) papers were used as raw material and water-based Firetex (stone water) commercial product was used as fire retardant. Waste papers were refibrilled in the pulper and recycled with the rapid-köthen machine. Firetex was applied to the papers at 25%, 50%, 75% and 100% concentrations by immersing method. The thermal, mechanical and optical properties of the test papers produced within the scope of the study were measured and optimized. In the study, as a result of the thermogravimetric (TGA) analyzes of the test samples, it was determined that the carbonization and residue amount increased significantly with the increased Firetex ratio. It was determined that the limit oxygen index (LOI) values of the samples also increased with the increasing Firetex ratio, the LOI value of 26 accepted as the standard with 50% concentration was exceeded, and the device limits were exceeded in the samples treated with 100% fire retardant. It has been determined that the increased Firetex ratio improves the resistance against burning, while reducing the tensile and tearing resistance. As a result of the study, when the LOI and strength values are considered together, the most suitable Firetex concentration for waste newspaper is determined as 50%.
- Published
- 2022
5. Investigation of thermal and optical properties of waste newspaper with bacterial cellulose and borax additives
- Author
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ERSOY KALYONCU, Evren and PEŞMAN, Emrah
- Subjects
Fen ,Waste newspaper ,Bacterial cellulose ,Borax pentahydrate ,Thermogravimetric analysis ,Optical properties ,Science ,Atık gazete kağıdı ,bakteriyel selüloz ,boraks pentahidrat ,termogravimetrik analiz ,optik özellikler - Abstract
Bu çalışmada geri dönüştürülmüş atık gazete kağıtlarından üretilmiş kağıtlara katkı maddesi olarak bakteriyel selüloz (BS) ilavesinin ve kağıdın yanma özelliğini geciktirmek amacıyla boraks pentahidrat (Na2B4O7.5H2O) uygulamasının, üretilen kağıtların termal ve optik özellikleri üzerine etkileri araştırılmıştır. Boraks uygulaması için daldırma yöntemi seçilmiş olup karşılaştırma yapabilmek için üretim esnasında boraks ilavesi de çalışılmıştır. Kağıtların yanma karakteristikleri ve kinetiğini belirlemek için termal özellikleri belirlenmiştir. Optik özellikleri için parlaklık, sarılık ve renk değerleri (L*,a*,b*) belirlenmiştir. TGA verileri değerlendirildiğinde daldırma yöntemi ile boraks uygulaması sonucu dönüm noktası sıcaklığının 377,53 °C’den 335,55 °C’ye düştüğü, sadece BS katkısı ile 379,53 °C’ye bir miktar artış gösterdiği tespit edilmiştir. BS katkılı kağıtların daldırma yöntemi ile boraks uygulaması sonucunda dönüm noktası sıcaklığının 334,24 °C’ye düştüğü ve %44,03 oranı ile diğer örneklere göre en yüksek 590 °C deki kalıntı miktarı verdiği belirlenmiştir. Sonuç olarak daldırma yöntemi ile boraks uygulaması yapılan BS katkılı kağıtların termal dayanımlarının diğerlerine göre daha iyi olduğu, BS ve boraksın kağıdın yanması sırasında kalori oluşumunu azalttığı dolayısı ile yanmayı hızlı bir şekilde sonlandırdığı, optik özellikler açısından BS katkısının ve boraks uygulamasının kağıdın parlaklık değerini azalttığı, sarılık değerini arttırdığı belirlenmiştir., In this study, the effects of bacterial cellulose (BC) and the borax pentahydrate (Na2B4O7.5H2O), which was applied to retard the burning property of the paper, additives as reinforcement to the recycled waste newspaper were investigated, on the thermal and optical properties of the produced papers. The immersed method was chosen for the borax application, and the addition of borax during production was also studied to make a comparison. In order to determine the burning characteristics and kinetics of the papers, their thermal properties were detected. Brightness, yellowness, and color values (L*, a*, b*) were determined for optical properties. When the TGA data were evaluated, it was determined that the inflection point temperature decreased from 377.53 °C to 335.55 °C as a result of borax application with the immersion method, and it increased slightly to 379.53 °C with only BS additive. The results of the borax application of BS reinforced papers by the immersion method showed that the inflection point temperature decreased to 334.24 °C, and it had the highest residual amount at 590 °C with a rate of 44.03% compared to the other samples. As a result, the thermal resistance of BS reinforced papers with borax application with the immersed method is better than the other samples. BS and borax reduce the formation of calories during the burning of the paper; thus, this ends the burning quickly. In terms of optical properties, it was found that BS reinforcement and borax application reduce the brightness value and increase the yellowness of the paper.
- Published
- 2022
6. Investigation of Thermal Degradation Kinetics of Pyrazabole Centered Two-Armed Poly(methyl methacrylate).
- Author
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KURT, Adnan, AYAZ, Handan, and GÜLTEK, Ahmet
- Abstract
Copyright of Adiyaman University Journal of Science & Technology / Adıyaman Üniversitesi Fen Bilimleri Dergisi is the property of Adiyaman University, Institute of Science / Adiyaman Universitesi Fen Bilimleri Enstitusu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2016
7. Preparation, Characterization of n-Hexadecane-based Microcapsules as a Phase Change Material and Determination of Its Thermal Performance via T-History Method
- Author
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Mehmet Selçuk Mert and Hatice Hande Mert
- Subjects
Thermogravimetric analysis ,Materials science ,business.industry ,Phase Change Material,Microencapsulation,Thermal Energy Storage,T-History Method ,Mühendislik ,Thermal energy storage ,Phase-change material ,Energy storage ,Faz Değiştiren Madde,Mikrokapsülasyon,Isıl Enerji Depolama,T-Kayıt Yöntemi ,Differential scanning calorimetry ,Engineering ,Chemical engineering ,Latent heat ,Heat transfer ,business ,Thermal energy - Abstract
Faz değiştiren maddeler (FDM’ler), ısıl enerjinin gizli ısı olarak depolanabilmesine olanak sağlayan, sıvıdan katıya ya da katıdan sıvıya faz değişimi esnasında büyük miktarda ısının depolanmasına veya salınmasına izin veren yeni nesil enerji depolama malzemeleridir. FDM’lerin faz değişimi esnasında belirli bir hacimde tutmak amacıyla makro veya mikro/nano ölçekte kapsüllenmeleri gerekmektedir. Kapsülleme işlemi sayesinde malzemenin dış çevrelerden etkilenme derecesi azaltıldığı gibi malzemenin katıdan sıvıya geçişi esnasında mevcut kabuk hacminde sabit tutulması mümkün olmakta ve ısı transfer yüzeyi de arttırılmaktadır. Bu çalışmada, organik FDM’ler sınıfında yer alan bir parafin olan ve binalarda iç ortamın ısıl konforunun sağlanması hususunda uygun faz değişim sıcaklık aralığı sayesinde ısı depolama malzemesi olarak kullanım potansiyeli bulunan n-hekzadekan (n-HD), faz inversiyon emülsifikasyonu yöntemiyle mikro boyutta kapsüllenmiştir. Faz dönüşümü esnasında sızdırma problemi nedeniyle doğrudan uygulamalarda kullanımı uygun olmayan n-hekzadekanın kapsülleme işleminde, kabuk olarak binalarda yalıtım amaçlı sıklıkla kullanılan stiren (St) ve çapraz bağlayıcı divinilbenzen (DVB) kullanılmıştır. Elde edilen mikrokapsüllerin ısıl özellikleri diferansiyel taramalı kalorimetre (DSC) ve Termogravimetrik Analiz (TGA) ile incelenirken, morfolojik özellikleri ve kimyasal yapısı ise sırasıyla Taramalı Elektron Mikroskobu (SEM) ve Fourier Dönüşümlü Kızılötesi (FT-IR) spektroskopisi ile belirlenmiştir. Elde edilen mikrokapsüllerin erime entalpisi 131,074 J/g olarak bulunurken, FDM içeriği %68,55 olarak hesaplanmıştır. Mikrokapsüllenmiş FDM’nin (MikroFDM) ve saf n-hekzadekanın ısı depolama özellikleri ısıtmalı-soğutmalı sirkülasyonlu bir banyo sisteminde karşılaştırmalı olarak test edilmiştir. T-Kayıt yöntemiyle gerçekleştirilen ölçümlerde elde edilen ısıl özellikler DSC analizinden elde edilen sonuçlarla karşılaştırmalı olarak sunulmuştur. N-hekzadekan faz değişim maddesini içeren mikrokapsüllerin sahip oldukları boyut aralığı, faz değişim sıcaklık aralığı, ısı depolama kapasitesi ve gösterdikleri ısıl performans açısından binalarda iç mekan uygulamalarında ısıl konforun sağlanması noktasında kullanımının uygun olduğu ve binalarda enerji tasarrufu açısından önemli kazanımlar sağlayabilecekleri öngörülmüştür., Phase change materials (PCMs) are new generation energy storage materials that allow the storage of thermal energy as latent heat, allowing the storage or release of large amounts of heat during the phase change from liquid to solid or solid to liquid. PCMs have to be encapsulated on a macro or micro / nano scale to maintain a certain volume during phase change. By means of the encapsulation process, the degree to which the material is affected from external environments is reduced and it is possible to keep the material constant volume during the phase change process of the material from solid to liquid and the heat transfer surface is increased. In this study, n-hexadecane (n-HD), which is a paraffin which is in the class of organic PCMs and which has the potential to be used as heat storage material with the appropriate phase change temperature range in order to provide the thermal comfort of the indoor environment in buildings, is encapsulated in micro-dimension by phase inversion emulsification method. Styrene (St) and cross-linker divinylbenzene (DVB), commonly used for insulation purposes in buildings, were used as the shell in the encapsulation process of n-hexadecane, which is not suitable for direct applications due to leakage problems during phase change process. The thermal properties of the obtained microcapsules were investigated by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) whereas morphological properties and chemical structure of them were determined by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR), respectively. The melting enthalpy of the obtained microcapsules was 131,074 J / g, while the PCM content was calculated as 68.55%. The heat storage properties of microencapsulated PCM (MicroPCM) and pure n-hexadecane were comparatively tested in a heated-cooled circulation bath system. The thermal properties obtained in the measurements performed by T-History method are presented in comparison with the results obtained from DSC analysis. It is envisaged that microcapsules containing n-hexadecane phase change material are suitable for use in indoor applications in buildings in terms of particle size range, phase change temperature range, heat storage capacity and thermal performance and they can provide significant gains in terms of energy savings in buildings.
- Published
- 2020
8. Experimental investigation of mechanical and thermal properties of nano particle doped polyurethane adhesives
- Author
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Tongur, Mehmet, Ataberk, Necati, Danışman: 0000-0002-5394-9549, and NEÜ, Fen Bilimleri Enstitüsü, Makine Mühendisliği Anabilim Dalı
- Subjects
Nanokompozitler ,Differential Thermal Analysis ,Mechanical and Thermal Properties ,Polyurethane Adhesives ,Scanning Electron Microscopy ,Thermogravimetric analysis ,Poliüretan yapıştırıcılar ,Taramalı Elektron Mikroskopi ,Diferansiyel Termal Analiz ,Mekanik ve Termal Özellikler ,Termogravimetrik Analiz ,Nanocomposites - Abstract
Yüksek Lisans Tezi, Bu tez çalışmasında, poliüretan yapıştırıcıyla birleştirilmiş bağlantıların mekanik ve termal özelliklerini geliştirmek amacıyla ağırlıkça farklı oranlarda (%0, % 0.05, % 0.10 ve % 0.15) grafen (GR) ve çok cidarlı karbon nanotüp (ÇCKNT) ilave edilerek nanokompozit poliüretan yapıştırıcılar üretilmiştir. Nanoparçacık türü ve katkı oranının etkisini incelemek amacıyla Al 2024-T3 ve 8 katmanlı karbon takviyeli kompozit levhalar kullanılarak tek taraflı bindirmeli bağlantılar (TTBB) üretilmiştir. Üretilen numunelerin mekanik özelliklerini belirlemek amacıyla sabit çekme yükü altında ASTM D1002-10 standardına uygun olarak mekanik testler gerçekleştirilmiştir. Poliüretan yapıştırıcının güçlendirilmesinde kullanılan nanoparçacıkların dağılımı ve kırılma yüzeylerin morfolojisi SEM analizleri ile görüntülenmiştir. Yapıştırıcı numunelerin termal özelliklerini araştırmak için Termogravimetrik Analiz (TGA) ve Diferansiyel Termal Analiz (DTA) testleri uygulanmıştır. DTA testi ile yapıştırıcı numunelerinin camsı geçiş sıcaklığı (Tg), erime sıcaklığı (Tm) ve erime entalpisi (Hm) elde edilmiş olup TGA testleriyle de üretilen numunelerin kütle kaybına bağlı olarak sıcaklık değişimleri elde edilmiştir. Poliüretan yapıştırıcıyla birleştirilmiş TTBB numunelerinin mekanik özellikler açısından en uygun bağlantı ağırlıkça %0.10 grafen ve %0.15 ÇCKNT içeren alüminyum-alüminyum TTBB'lerde görülmektedir. Çekme numunelerinde ise mekanik özellikler açısından en uygun yapıştırıcı ağırlıkça %0.05 grafen ve %0.10 ÇCKNT içeren numunelerde görülmektedir. Termal özellikler açısından değerlendirildiğinde ise üretilen numunelerden en yüksek kütle kaybı başlangıç sıcaklığı 333.88 °C ile ağırlıkça %0.05 grafen içeren numunede, en yüksek tamamen bozulma sıcaklığı 527.7 °C ile %0.10 ÇCKNT içeren numunede, en yüksek erime sıcaklığı (Tm) 300.36 °C ile %0.05 grafen içeren numunede ve en yüksek camsı geçiş sıcaklığı (Tg ) sıcaklığı 56.54°C ile %0.05 grafen içeren numunede elde edilmiştir., In this thesis, nanocomposite polyurethane adhesives were produced by adding different ratios (%0, % 0.05, % 0.1 and % 0.15) of graphene (GR) and Multi-Walled Carbon Nanotube (MWCNT) to improve the mechanical and thermal properties of the polyurethane adhesive bonded connections. In order to examine the effect of nanoparticle type and additive ratio, single lap joints (SLJ) were produced using Al 2024-T3 and 8-layer carbon-reinforced composite plates. While determining the mechanical properties of SLJ, mechanical tests were carried out in accordance with ASTM D1002-10 standard under stable tensile load. The distribution of the nanoparticles and the morphology of the failure surfaces were analyzed by scanning electron microscopy (SEM) images. Thermogravimetric analysis (TGA) and Differential Thermal Analysis (DTA) tests were applied to investigate the thermal properties of the adhesive samples. The glass transition temperature (Tg), melting temperature (Tm) and melting enthalpy (Hm) of the adhesive samples produced by the DTA test were obtained and decomposition temperatures of the samples produced in the TGA tests were obtained with respect to mass loss. In terms of mechanical properties, the most appropriate connection of polyurethane adhesive bonded SLJ connections samples was seen in aluminium-aluminium SLJs containing percentage by weight %0.10 graphene and %0.15 MWCNT. As for adhesive samples, the most appropriate adhesive was seen in samples containing percentage by weight %0.05 graphene and %0.10 MWCNT. When evaluated in terms of thermal properties, the highest mass loss from the produced samples was observed in the sample containing the starting temperature of 333.88 ° C and 0.05% by weight of graphene, the sample with the highest total decomposition temperature of 527.7 ° C and %0.10 by weight of MWCNT, the sample with the highest melting temperature (Tm) of 300.36 ° C and %0.05 by weight of graphene and the highest glass transition temperature (Tg) temperature was obtained 56.54 ° C in the sample containing % 0.05 graphene.
- Published
- 2020
9. DOLGU MADDESİ OLARAK KULLANILAN FARKLI UÇUCU KÜLLERİN SERT POLİÜRETAN KÖPÜK MALZEMELERİN MEKANİK ÖZELLİKLERİ İLE ISIL VE YANMA DAVRANIŞLARI ÜZERİNE ETKİLERİ.
- Author
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YURTSEVEN, Recep, TARAKCILAR, Ali Rıza, and TOPÇU, Muzaffer
- Subjects
- *
FLY ash , *COAL-fired power plants , *POLYURETHANES , *POLYMERS , *THERMAL stability , *FIRE resistant materials - Abstract
Fly ash which is a by-product of coal-fired power stations has been used as filler in different polymeric materials for different purposes. Since the chemical composition and the size of fly ash may vary depending on the coal type and combustion, properties of fly ash should be examined before the incorporation of fly ash into polymeric materials. In this study, two fly ashes which have different chemical compositions are used as filler in rigid polyurethane foams. The fly ashes were added in 5 %, 10 %, 15 % and 20 % in the total mass. The morphology of polyurethane foam cells was observed by using scanning electron microscopy and the effects of two different fly ashes on the thermal conductivity, the compressive strength, thermal stability and flammability of rigid polyurethane foams were investigated. Experimental results indicated that fly ash addition into rigid polyurethane foam has no negative effects on thermal conductivity of the materials; however it caused decreasing in the compression strength within the acceptable limits. In addition, it was determined that the foam materials filled with the fly ash containing high amount of SiO2 shows better fire resistance and thermal stability. [ABSTRACT FROM AUTHOR]
- Published
- 2013
10. Mobilya Fabrikası Atık Tozunun İzotermal Olmayan Şartlarda Gerçekleştirilen Pirolizinin Kinetik Parametrelerinin Belirlenmesi.
- Author
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Taşar, Şeyda, Duranay, Neslihan, and Yilgin, Melek
- Subjects
- *
DYNAMICS , *PYROLYSIS , *INDUSTRIAL wastes , *FURNITURE industry , *HEMICELLULOSE , *GRAVIMETRIC analysis - Abstract
A pyrolysis study of furniture plant waste dusts is carried out under nitrogen flow rate of 10 ml/min. and heating rate of 10 ºC/min. at between 25-900 ºC in a TGA equipment. As a result of the pyrolysis of waste dusts, three region were determined on thermographs. Regression constants for the different theorical model equations that representing degradation were calculated by Coast-Redfern method. And according to regression coefficients, kinetic model which the best representing degradation, was determined. In the study, the kinetic parameters were determined for the second and third decomposition steps, separately. Best model equations representing degradation for total reaction, second degradation step that hemicellulose and cellulose degraded, third degradation step that lignin degraded was found to be chemical kinetic F(3) equation, Ginstling-Brounshtein (D4) and Jander (D3) equations and chemical kinetic F(3) equation, respectively. By using best model equations representing degradation, activation energies and ln (A/min-1) were determined to be 77.54-82.32 kJ/mol and 10.45-11.60, respectively for second degradation step that hemicellulose and cellulose degraded and 52.40 kJ/mol and 5.07 same respectively for third degradation step that lignin degraded. Kinetic parameters were found to be 54.89 kJ/mol, 9.33 for the total reaction. [ABSTRACT FROM AUTHOR]
- Published
- 2011
11. NaOH ile Modifiye Edilmiş Kızılçam (Pinus brutia Ten.) Yongalarının Levha Üretimindeki Performansı
- Author
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Samim Yaşar and Abdullah Beram
- Subjects
0106 biological sciences ,Thermogravimetric analysis ,Absorption of water ,Mühendislik ,02 engineering and technology ,Kızılçam,alkali işlem,kimyasal bileşim,yongalevha,fiziksel ve mekanik özellikler ,01 natural sciences ,chemistry.chemical_compound ,Engineering ,Pinus brutia ,010608 biotechnology ,medicine ,Thermal stability ,Hemicellulose ,Cellulose ,Fourier transform infrared spectroscopy ,biology ,General Medicine ,021001 nanoscience & nanotechnology ,biology.organism_classification ,chemistry ,Brutian pine,alkali treatment,chemical composition,particleboard,physical and mechanical properties ,Swelling ,medicine.symptom ,0210 nano-technology ,Nuclear chemistry - Abstract
In this study, particles from brutian pine (Pinus brutia Ten.) weresoaked in 0.25, 0.50, 0.75 and 1% NaOH solutions. The changes in the chemicaland thermal properties of the particles caused by these treatments were indicatedand the effects of these treatments on the physical and mechanical propertiesof the produced boards were evaluated. Main chemical component and fouriertransform infrared (FTIR) spectroscopic analysis showed that the extractive,hemicellulose and lignin content of the particles decreased during the alkalitreatments, while the cellulose content increased. Thermogravimetric analysis(TGA) indicated that the particles treated with NaOH solutions exhibited lowerthermal stability than the untreated particles. Alkali treatments caused water absorption (WA) and thickness swelling(TS) increase of the produced particleboards. The mechanical properties of theproduced particleboards were improved by alkali treatments. The modulus ofelasticity (MOE), modulus of rupture (MOR) and internal bond (IB) strengthvalues of the produced particleboards met the requirements for general-purposeparticleboards used in dry conditions, as defined by the TS-EN 312 (2012)standard., Bu çalışmada, %0.25,0.50, 0.75 ve 1’lik NaOH çözeltileri ile işlem görmüş kızılçam (Pinus brutia Ten.) yongalarının kimyasal bileşimindeki ve termalözelliklerindeki değişimler ve bu değişimlerin üretilen levhaların fiziksel ve mekaniközellikleri üzerine etkileri değerlendirilmiştir. Ana kimyasal bileşen vefourier dönüşümlü kızılötesi (FTIR) spektroskopisi analizleri, alkaliişlemlerde NaOH derişimi arttıkça yongalardaki ekstraktif madde, lignin vehemiselüloz miktarlarında sürekli düşüş, selüloz miktarında ise sürekli artışolduğunu göstermiştir. Termogravimetrik analiz (TGA) sonuçları, alkali işleminyongaların termal dayanıklılığını düşürdüğünü ortaya koymuştur. Uygulananalkali işlemler, üretilen levhaların su alma (SA) ve kalınlığına şişme (KŞ)değerlerini sürekli artırmıştır. Üretilen levhaların mekanik özelliklerininuygulanan alkali işlem derişimi arttıkça gelişme gösterdiği belirlenmiştir.Çalışmada üretilen levhalarda belirlenen eğilmede elastikiyet modülü (EM),eğilme direnci (ED) ve yüzeye dik çekme direnci (YDÇD) değerlerinin TS EN 312(2012) standardında belirtilen kuru şartlarda genel amaçlı kullanılan levhalariçin beklenilen değerlerden yüksek olduğu görülmüştür.
- Published
- 2018
12. Bamya müsilajının termo-reolojik özelliklerinin belirlenmesi
- Author
-
Öncü Glaue, Şelale, Tavman, Şebnem, Gıda Mühendisliği Anabilim Dalı, and Fen Bilimleri Enstitüsü
- Subjects
Ultrasonik Ekstraksiyon ,Okra ,Differential Scanning Calorimeter ,Ultrasonic Extraction ,Reoloji ,Muscillage ,Bamya ,Musilaj ,Thermogravimetric Analysis ,Ultrason ,Food Engineering ,Fark Tarama Kalorimetresi ,Extraction Ultrasound ,Rheology ,Gıda Mühendisliği ,Termogravimetrik Analiz - Abstract
Bu tez çalışmasında, beslenme ve sağlık açısında değerli bir ürün olan bamya sebzesinde bulunan müsilaj kısmı ultrason destekli ekstraksiyonla elde edilmiş, kimyasal ve fiziko kimyasal yöntemlerle bu polisakkarit ekstraktının yapısal, ısıl ve reolojik özellikleri belirlenmiştir. Isıl özelliklerden camsı geçiş sıcaklığı, erime sıcaklığı ile faz değişim entalpilerinin belirlenmesinde diferansiyel tarama kalorimetresi kullanılmıştır. Değişik katı/çözgen oranlarında (1:10, 1:25, 1:30, 1:50) 5 ve 30 dakikalık ekstraksiyon süreleri ekstraksiyona tabi tutularak elde edilen örneklerin camsı geçiş sıcaklıkları ortalama 50oC civarında, erime sıcaklıkları ise 166 – 170oC aralığında bulunmuştur. Bamya polisakkaritlerinin termal stabilitesini analiz etmek için termogravimetri (TG) ve diferansiyel termogravimetri (DTG) teknikleri kullanılmıştır ve sonuçlar bamya müsilajının termal stabilitesinin iyi olduğunu göstermiştir. Gıdaların ısıl iletkenlik ölçümünde daha önce hiç kullanılmamış olan 3ω yöntemiyle ısıl iletkenlik ölçümü yapılmış ve bamya polisakkaritinin ısıl iletkenlik değerlerinin sudan çok farklı olmadığı tespit edilmiştir. Ekstraktlardaki bileşim hakkında detaylı bilgi veren, polisakkaritlerin içerdiği bağları aydınlatmaya yarayan, farklı bamya/distile su oranları ve farklı ekstraksiyon süreleri sonucu elde edilen polisakkaritlerin karakterizasyonu amacıyla FTIR analizleri yapılmıştır. Bamyanın galaktoz, ramnoz ve galakturonik asit olan ana bileşenleri FTIR analiz spektrumunda gözlemlenebilmiştir. Çalışmada farklı bamya/distile su oranında (1:10 ve 1:30) ekstrakte edilen polisakkaritlerin farklı konsantrasyonlardaki (%1, 2, 3, 4; w/v) çözeltilerinin, değişik sıcaklıklardaki (10, 20, 40, 60, 80oC) akış davranış özellikleri incelenmiştir. Reolojik özellikler Power Law (Üssel) modele göre analiz edilmiş ve parametreler hesaplanmıştır. Bamya polisakkaritlerinin Newton dışı psödoplastik akış karakteristiğini gösterdiği gözlenmiştir. Akış davranışı indeksinin 0,234 ile 0,947 arasında, kıvam katsayısının ise 0,00437 ile 0,2445 Pa.sn arasında değiştiği görülmüştür. Kıvam katsayısı (K), ve akış davranış indeksi (n) sıcaklık arttıkça azalmıştır. Aynı şekilde K değeri konsantrasyon arttıkça artmaktadır. Akış davranış indeksi (n) değerleri ise konsantrasyon ile düzenli bir davranış göstermemiştir. Bamya polisakkarit örneklerinin görünür viskozitelerine sıcaklığın etkisi 10 – 80oC arasında beş farklı sıcaklıkta incelenmiştir. Ölçümler sonunda kıvam katsayısının sıcaklıkla değişim grafiği çizilmiş ve kıvam indeksine sıcaklığın etkisi Arrhenius denklemi ile modellenmiştir. 1:10 ve 1:30 katı/çözgen oranına sahip iki örnekte de konsantrasyon arttıkça aktivasyon enerjisi artmıştır ve 1:10, %4 konsantrasyon için en yüksek aktivasyon enerjisi değerine ulaşılmıştır (275,8434 kj/mol). Sonuç olarak elde edilen bu polisakkaritler, yapılan analizler sayesinde yapışkan ve gamsı yapısı sayesinde kıvam arttırıcı olarak gıda sanayisinde, atıklarının yüksek adsorbsiyon kapasitesine sahip olması özelliği ile atık su arıtma sistemlerinde, emülsiyonlaştırıcı ve süspanse edici ajan olarak farmasotik gibi alanlarda kullanımı yaygınlaştırılabilecektir., In this thesis, the mucilage portion of the okra which is a valuable product in terms of nutrition and health was obtained by ultrasound assisted extraction, and the structural, thermal and rheological properties of this polysaccharide extract were determined by chemical and physicochemical methods. In the determination of phase change enthalpy by investigating the glass transition temperature and enthalpy, the differential scanning calorimetry was used. At various solid / solvent ratios (1:10, 1:25 1:30 1:50) and extraction times of 5 and 30 minutes, the glass transition temperatures of the samples were found to be approximately 50oC and melting temperatures in the range of 166-170°C. Thermogravimetry (TG) and differential thermogravimetry (DTG) techniques were used to analyze the thermal stability of Okra polysaccharides and the results showed that the thermal stability of the okra mucilage was good. Thermal conductivity was measured by 3 ω method and it was determined that the thermal conductivity values of okra polysaccharide were not much different from water. FTIR analysis was carried out for the characterization of polysaccharides obtained by different extraction times and different rates of okra / distilled water, which provide detailed information about the composition of the extracts, to illuminate the bonds of polysaccharides. The main components of okra which were galactose, rhamnose and galacturonic acid can be observed in the FTIR analysis spectrum. In the study, flow behavior characteristics of the polysaccharides extracted at different okra / distilled water ratio (1:10 and 1:30), at different concentrations of polysaccharides (1%, 2, 3, 4; w / v) of the extracts at different temperatures (10, 20, 40, 60, 80oC) were investigated. The rheological properties were analyzed according to the Power Law model and the parameters were calculated. It was observed that okra polysaccharides showed non-Newton pseudoplastic flow characteristics. Flow behavior index varied between 0.234 and 0.947, and the consistency coefficient varied between 0.00437 and 0.2445 Pa.sn. The consistency coefficient (K), and the flow behavior index (n) decreased as the temperature increased. In the same way, the K value increases as the concentration increases. The flow behavior index (n) values did not show a regular behavior with concentration. The effect of temperature on apparent viscosities of okra polysaccharide samples was investigated at five different temperatures between 10 – 80oC. At the end of the measurements, a graph of change of consistency coefficient with temperature was drawn and the effect of temperature on the consistency index was modeled by the Arrhenius equation. In two samples with a 1:10 and 1:30 solid / solvent ratio, the activation energy increased as the concentration increased, and the highest activation energy value was reached for the 1:10, 4% concentration (275,8434 kj / mol). As a result, these polysaccharides can be used in the food industry as a thickening agent due to their adhesive and viscous structure and in the wastewater treatment systems with their high adsorption capacity, and their use as emulsifier and suspension agent in the fields such as pharmaceuticals.
- Published
- 2018
13. Investigation of gasification characteristics of Ilgın coals by thermogravimetric analysis method
- Author
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Çınar, İbrahim, Altun, Mustafa, Selçuk Üniversitesi, Mühendislik Fakültesi, Maden Mühendisliği Bölümü, Çınar, İbrahim, and Altun, Mustafa
- Subjects
Kömür gazlaştırma ,Mühendislik ,Coal gasification ,Jeoloji ,Termogravimetrik analiz ,Thermogravimetric analysis ,Maden İşletme ve Cevher Hazırlama - Abstract
Kömür oluşumu itibariyle heterojen bir yapıya sahiptir. Bundan dolayı kömürün gazlaşmasını etkileyen birçok etken vardır. Isıl analiz kömürün gazlaşma özelliklerinin belirlenmesinde ve bu etkenlerin kömürün gazlaşma özellikleri üzerindeki etkilerinin incelenmesinde en iyi yöntemlerden birisidir. Bu çalışmada Ilgın kömürlerinden alınan numunelerle belirlenen sıcaklıklarda dönüşüm süreleri ve gazlaşma hızları termogravimetrik analiz yöntemiyle belirlenmiş sıcaklığın bu faktörler üzerindeki etkileri incelenmiştir. Ilgın kömürleri 700C, 750C, 800C ve 850C sıcaklıklarda CO2 atmosferinde termogravimetrik analiz cihazı kullanılarak gazlaştırılmış dönüşüm oranları ve gazlaşma hızları incelenmiş ve numuneler arasında karşılaştırmalar yapılmıştır. Ilgın kömürünün 800C sıcaklıkta diğer sıcaklıklara göre daha kısa sürede dönüşümünün tamamlandığı görülmüştür., Coal formation has a heterogeneous structure. Therefore, there are many factors affecting the coal gasification. Thermal analysis in determining the properties of the coal gasification and the effects on characteristics of the coal gasification these factors is one of the best procedure for the evaluation. In this study, the transformation times and gasification rates of the samples taken from the Ilgın coal were determined by thermogravimetric analysis and the effects of temperature on these factors were investigated. Conversion time and gasification rates of Ilgın coals were investigated using thermogravimetric analyzer at 700C, 750C, 800C and 850C in CO2 atmosphere and comparisons were made between samples. It was observed that the conversion time of the Ilgın coal at 800C was shorter than the other temperatures.
- Published
- 2018
14. Synthesis and properties of a spinel cathode material for lithium ion battery with flat potential plateau
- Author
-
Aseel B. Al-Zubaidi, Ahmed A. Al-Tabbakh, and Norlida Kamarulzaman
- Subjects
Thermogravimetric analysis ,Materials science ,Scanning electron microscope ,Li-ion batteries,transition-metal compounds,combustion synthesis,electrochemical properties,X-ray diffraction ,Spinel ,Analytical chemistry ,General Physics and Astronomy ,engineering.material ,Lithium-ion battery ,law.invention ,law ,X-ray crystallography ,engineering ,Calcination ,Particle size ,Faraday efficiency - Abstract
A potential cathode material for lithium ion battery was synthesised by combustion reaction. The thermal behaviour of the as-synthesised precursor was measured using a thermogravimetric analyser and the range of calcination temperature from 500 $^{\circ}$C to 800 $^{\circ}$C was determined. X-ray diffraction analysis showed that all calcined powders crystallised in the cubic spinel structure of the $Fd\bar{3}m$ space group. The particle size distributions and morphologies of the powders were obtained using a particle size analyser and scanning electron microscope. The effect of calcination temperature on the electrochemical performance was investigated using galvanostatic charge/discharge measurements. The potential profiles of charge and discharge exhibited flat plateaus, emphasising that the synthesised batteries are not super capacitors. Results showed that the batteries prepared from powders calcined at 800 $^{\circ}$C exhibited higher coulombic efficiency and better cycling performance than powders calcined at 500 $^{\circ}$C.
- Published
- 2015
15. Synthesis and characterization of thermally stable camphor-based polyimide--clay nanocomposites
- Author
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Süleyman Köytepe, Murat Yiğit, Beyhan Yiğit, and Turgay Seçkin
- Subjects
Thermogravimetric analysis ,Thermal decomposition ,General Chemistry ,chemistry.chemical_compound ,Differential scanning calorimetry ,Montmorillonite ,chemistry ,Chemical engineering ,Polymer chemistry ,Organoclay ,Thermal stability ,Glass transition ,Polyimide ,Polyimide,nanocomposites,organoclay,clay dispersion - Abstract
A new monomer was prepared from (1R,3S)-(+)-camphoric acid. Novel polyimide and polyimide--clay hybrid composites were developed from one-pot condensation reactions of this monomer and pyromellitic dianhyride. Polyimide-montmorillonite nanocomposites were prepared from solution of polyimide and with different weight percentages (1, 5, 10 wt %) of organo-modified montmorillonite (OM-MMT) using N-methyl-2-pyrrolidone (NMP) as aprotic solvent. The reactive organoclay was formed by using hexadecylpyridinium chloride as a swelling agent for silicate layers of montmorillonite. The polyimide--clay composites films (PI--MMT) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). All composites were subjected to differential scanning calorimetry measurements for the purpose of examining Tg from all compositions. The clay content significantly influenced the thermal behavior of the polymeric films, such as glass transition and decomposition temperatures of polyimide--clay composites. The glass transition temperatures of the composites were higher than that of the original polyimide. Their thermal decomposition temperatures (Td = temperature at 5% mass loss) were measured via thermogravimetric analysis and showed that the introduction of clay into polymer backbones increased thermal stability. SEM, XRD, and the other conventional techniques were used for structural characterization. Dispersion of the modified clay in the polyimide matrix resulted in nanostructured material containing intercalated polymer between the silicate layers. The morphology and properties of PI nanocomposites greatly depend on the functional groups of the organic modifiers, synthesis procedure, and structure of polyimide because of the chemical reactions and physical interactions involved.
- Published
- 2014
16. Possibilities for reducing tractor engine friction losses at cold start using an ultrasonic irradiation technique
- Author
-
Florin Mariasiu
- Subjects
Thermogravimetric analysis ,Materials science ,Aqueous solution ,Ecology ,Key words: Cold start,engine,lubrication,oil,simulation,ultrasonic,viscosity ,Forestry ,chemistry.chemical_compound ,Monomer ,Dimethylglyoxime ,chemistry ,Copolymer ,Reactivity (chemistry) ,Methyl methacrylate ,Fourier transform infrared spectroscopy ,Food Science ,Nuclear chemistry - Abstract
Challenges to the effectiveness of specific activities and production technologies in agriculture become more pressing each day as worldwide demand for agricultural products increases. The mechanization of agriculture brings positive quantitative and qualitative effects; however, the modernization of production tools (tractors and agricultural machinery) needs to be directly linked to increasing economic efficiency of use. Period of use and life expectancy of agricultural tractors can be increased by reducing the friction and wear that occurs among moving mechanical parts. A special case in point is the cold start process in compression ignition engines. In a cold start great forces develop, and a lack of lubricating oil film can lead to the damage of engine components. This paper proposes use of an ultrasound emitter device that manages minimum energy consumption in order to modify the rheological properties of engine oil lubrication and reduce friction losses. The results of laboratory experiments were processed in a computer simulation of the diesel engine tractor cold start process. Losses due to internal friction among engine components were comparatively analyzed, and a lower percentage of friction loss was obtained through ultrasonic conditioning of lubricating oil. The proposed method offers benefits in terms of rational use and can prolong engine life with positive effects on the economic efficiency of agricultural processes.
- Published
- 2014
17. THE EFFECTS OF DIFFERENT FLY ASH FILLERS ON THE MECHANICAL PROPERTIES
- Author
-
Yurtseven, R, Tarakcilar, AR, and Topcu, M
- Subjects
Compressive Strength ,Thermogravimetric Analysis ,UL94 ,Rigid Polyurethane Foam ,Fly Ash ,Thermal Conductivity Coefficient - Abstract
Fly ash which is a by-product of coal-fired power stations has been used as filler in different polymeric materials for different purposes. Since the chemical composition and the size of fly ash may vary depending on the coal type and combustion, properties of fly ash should be examined before the incorporation of fly ash into polymeric materials. In this study, two fly ashes which have different chemical compositions are used as filler in rigid polyurethane foams. The fly ashes were added in 5 %, 10 %, 15 % and 20 % in the total mass. The morphology of polyurethane foam cells was observed by using scanning electron microscopy and the effects of two different fly ashes on the thermal conductivity, the compressive strength, thermal stability and flammability of rigid polyurethane foams were investigated. Experimental results indicated that fly ash addition into rigid polyurethane foam has no negative effects on thermal conductivity of the materials; however it caused decreasing in the compression strength within the acceptable limits. In addition, it was determined that the foam materials filled with the fly ash containing high amount of SiO2 shows better fire resistance and thermal stability.
- Published
- 2013
18. The effects of different fly ash fillers on the mechanical properties, thermal and fire behaviors of rigid polyurethane foams
- Author
-
Yurtseven, Recep, Tarakcilar, A.R., and Topçu, M.
- Subjects
Chemical compositions ,UL94 ,Compressive Strength ,Acceptable limit ,Fossil fuel power plants ,Mechanical properties ,Fly ash ,Fillers ,Rigid foamed plastics ,Coal ash ,Thermodynamic stability ,Coal combustion ,Coal-fired power stations ,Thermogravimetric Analysis ,Rigid polyurethane foams ,Thermal conductivity ,Rigid Polyurethane Foam ,Compression strength ,Polyurethane Foam ,Fire resistance ,Scanning electron microscopy ,Thermal Conductivity Coefficient - Abstract
Fly ash which is a by-product of coal-fired power stations has been used as filler in different polymeric materials for different purposes. Since the chemical composition and the size of fly ash may vary depending on the coal type and combustion, properties of fly ash should be examined before the incorporation of fly ash into polymeric materials. In this study, two fly ashes which have different chemical compositions are used as filler in rigid polyurethane foams. The fly ashes were added in 5 %, 10 %, 15 % and 20 % in the total mass. The morphology of polyurethane foam cells was observed by using scanning electron microscopy and the effects of two different fly ashes on the thermal conductivity, the compressive strength, thermal stability and flammability of rigid polyurethane foams were investigated. Experimental results indicated that fly ash addition into rigid polyurethane foam has no negative effects on thermal conductivity of the materials; however it caused decreasing in the compression strength within the acceptable limits. In addition, it was determined that the foam materials filled with the fly ash containing high amount of SiO2 shows better fire resistance and thermal stability.
- Published
- 2013
19. Çeşitli biyokütle numunelerinin yanma özelliklerinin incelenmesi
- Author
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Meteoğlu, Meltem, Küçükbayrak, Sadriye, Açma, Hanzade, Kimya Mühendisliği Ana Bilim Dalı, Kimya Mühendisliği, and Chemical Engineering
- Subjects
Thermogravimetric Analysis ,Biyokütle ,Yanma ,Combustion ,Biomass ,Chemical Engineering ,Kimya Mühendisliği ,Termogravimetrik Analiz - Abstract
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2006, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2006, Bu çalışmada, biyokütlenin yanma özelliklerini incelemek amacıyla Türkiye’nin çeşitli bölgelerinden toplanmış, farklı fiziksel ve kimyasal özelliklere sahip numuneler ile çalışılmıştır. 39 adet biyokütle numunesinin yanma profilleri termogravimetrik analiz kullanılarak elde edilmiştir. Biyokütle numunelerinin yanma profillerinden yaralanılarak; tutuşma sıcaklığı, yanma süresi, maksimum yanma hızı ve maksimum pik sıcaklığı gibi yanma özellikleri saptanmıştır. Isıl değer, elementel analiz, kısa analiz, ekstraktif madde, holoselüloz, alfa selüloz, lignin analizleri gerçekleştirilmiş ve yanma özelliklerine etkileri incelenip tartışılmıştır. Biyokütle numunelerinin yanma profilleri birbirinden önemli farklılıklar göstermektedir. Tutuşma sıcaklıkları 343-441K, yanma süreleri 38-70 dakika, maksimum yanma hızı 4.3-10.7 mg/dak ve bu hızın gerçekleştiği sıcaklık 436-534K arasında değişmektedir. Biyokütlelerin uçucu madde, sabit karbon, ekstraktif madde ve holoselüloz içerikleri yanma özelliklerini belirleyici rol oynamaktadır., In this study, different biomass samples that were collected from various regions of Turkey and which had different physical and chemical properties were investigated in order to determine their combustion properties. Burning profiles of 39 biomass samples were obtained through use of thermogravimetric analysis. Combustion properties like ignition temperature, burning time, maximum combustion rate and maximum heat temperature were determined using burning profiles of the biomass samples. Burning profiles of biomass samples differ from each other significantly. Ignition temperatures, burning times, maximum combustion rates and maximum peak temperatures are changing between 343-441 K, 38-70 min., 4.3-10.7 mg/min and 436-534 K, respectively., Yüksek Lisans, M.Sc.
- Published
- 2006
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