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Öğe Ağır metale maruz kalan çalışanların idrarlarındaki krom değerlerinin ICP-MS ile belirlenmesi ve analitik değerlendirmesi(2015) Poyraz, BayramBu çalışmada 3 aylık bir çalışma periyodunda, mesleki olarak ağır metale maruz kalmış laboratuar çalışanlarının idrarlarındaki krom değerleri belirlenmiş ve bu süreçteki değişim incelenmiştir. İdrar yoğunluklarını belirlemek için Endüktif Eşleşmiş Plazma Kütle Spektrometresi (ICP-MS) cihazı kullanılmıştır. Çalışmada analitik performans özellikleri de incelenmiş ve sonuçlar ngL-1 seviyelerinde verilmiştir. Çalışma sonucunda idrarların krom değerlerinin zamanla artış gösterdiği ve bu değerlerin zararlı maddeler ve hastalıklar birliği (ATSDR) tarafından belirtilen limit değerlerin üzerinde olduğu gözlenmiştir.Öğe Analysis, Assesment and Principal Component Analysis of Heavy Metals in Drinking Waters of Industrialized Region of Turkey(Univ Tehran, 2014) Poyraz, Bayram; Taşpınar, FatihSince they may expose to inorganic pollutants, drinking waters should be investigated and monitored in industrialized regions. In this study, drinking water samples taken from eight different locations in heavily industrialized region of Turkey, namely Marmara region, were analyzed to determine heavy metal and harmful trace element (Fe, Co, Cd, Hg, Pb, Zn, Sb, Cu, Ba, Mo, Cr, Mn and V) concentrations. Besides analytical analysis, principal component analysis (PCA) technique, spatial relationships related to these metal elements were also examined. Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) was used to determine the metal concentrations. The average concentrations in mu gL(-1) were as follows: Hg. Cd and Co BDL; Pb 0.18; Zn 27.32; Sb 0.04; Cu 6.35; Mn 2.15; Cr 1.07;V 1.86; Mo 0.52; Ba 35.22; Sr 252. The obtained results indicated that the heavy metals concentrations in drinking water samples did not exceed the limits values declared in the guidelines of WHO (World Health Organization), EPA (Environment Protection Agency) and TSE-266 (Turkish National Standards). However, some V and Cu concentrations found to be very close to tolerable limits declared by EPA.Öğe Application of modified cellulose nanofibrils as coating suspension on recycled paper using size press(Walter De Gruyter Gmbh, 2021) Fidan, Hakan; Tortuoglu, Ayhan; Tutus, Ahmet; Poyraz, Bayram; Arslan, Recai; Sertkaya, Selva; Killi, UfukCellulose based nanomaterials have the great potential to be applied to paper as bulk additive or coating material to improve overall final properties, especially in secondary fiber. In the present work, the effect of applying different kinds of cellulose nanofibrils (CNF) to papers obtained from recycled fibers using size press on physical, mechanical and barrier properties was investigated and compared with the sole use of starch as coating material. The coating process of CNF was carried out by the addition of size press grade starch to coating suspension. As a cellulose source, wheat straw was evaluated and CNF was obtained through oxidative and enzymatic pretreatments. Results indicate that starch/CNF suspension improves the overall paper properties. As a result of the deposition of coating suspension contains of 4 % wt. periodate-oxidized CNF onto paper surface, tensile and burst indices of papersheets increased as 52.2 % and 194.4 %. Significant decreases were observed in air permeability as 69.8 %. Compression tests also have been conducted to evaluate papersheets end-use properties. In comparison to the other pretreated CNF, due to is lower viscosity, applying periodate-oxidized CNF as size press significantly increased the mechanical properties of the papers fabricated from the recycled pulps.Öğe Biofilms from micro/nanocellulose of NaBH4-modified kraft pulp(Indian Acad Sciences, 2017) Tozluoğlu, Ayhan; Poyraz, Bayram; Candan, Zeki; Yavuz, Mustafa; Arslan, RecaiIndustrial applications of microfibrillated cellulose (MFC) and nanofibrillated cellulose (NFC) have been in use for some time; however, there is a need to improve the production steps and at the same time to obtain better quality products. NFC and MFC were generated from -modified kraft pulp, produced from a red gum tree plant (Eucalyptus camaldulensis). The generated NFC and MFC were characterized by high-performance liquid chromatography, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and -nuclear magnetic resonance (NMR). Morphological and viscoelastic properties were investigated by scanning electron microscopy and rheometry, respectively. The storage moduli of biofilms produced from NFC and MFC were investigated by dynamic mechanical thermal analysis (DMTA). Both exhibited mostly identical FTIR spectra. When the spectra were compared with those of -modified kraft pulp, minor shifts were observed due to crystallinity. In NMR spectra, disordered cellulose structures were observed for both NFC and MFC, and these findings were also confirmed by differential scanning calorimetry. Rheology studies revealed that the lowest viscosity was observed with MFC. TGA results showed that NFC degraded earlier compared with -modified kraft pulp. DMTA exhibited that NFC films had about six times higher storage modulus compared with MFC.Öğe Cellulose and lignin in place of EPDM and carbon black for automotive sealing profiles(Elsevier B.V., 2023) Poyraz, Bayram; Güner, Yusuf; Tozluoğlu, Ayhan; Aslan, RecaiThis study aims at using microcrystalline cellulose (MCC) and lignin in place of EPDM and carbon black with specified amounts to investigate the chemical, thermal, rheometric, mechanical, thermo-aging and morphological properties of EPDM elastomers. At the end of the study, the introduction of the MCC and lignin enabled higher elastic modulus and tear strength unlike tensile strength by revealing minor chemical shifts and lower thermal stability. In addition, the MCC and lignin facilitated the vulcanization process with fewer torque values by dispersing mostly homogeneously in the matrix. It was shown that all of the mechanical values were found to be in the range of the specified standard after the replacement of the MCC and lignin. © 2023 Elsevier B.V.Öğe DEVELOPING NANOCELLULOSE-BASED BIOFILMS FROM KRAFT AND NaBH4 - MODIFIED KRAFT PULP(Editura Acad Romane, 2018) Tozluoğlu, Ayhan; Poyraz, Bayram; Mcdonald, Armando G.; Candan, ZekiIn this study, both kraft pulp and NaBH4-modified kraft pulp produced from the red gum tree (Eucalyptus camaldulensis) were used to generate nanofibrillated cellulose (CNF) and microfibrillated cellulose (CMF). These were then characterized by HPLC, FTIR, DSC and C-13-NMR. Morphological and viscoelastic properties were investigated via SEM and rheometry, respectively. The storage moduli of the biofilms produced from the CNFs were investigated by dynamic mechanical thermal analysis (DMTA). Some minor shifts were observed in the 13C-NMR for the CMF and CNF obtained from NaBH4-modified kraft pulp. The CMF and CNF obtained from kraft pulp revealed higher thermal stability due to higher crystallinity. Higher dynamic mechanical properties were seen in the CNF film obtained from kraft pulp and the results were useful in ascertaining its potential application value.Öğe Düzce'de Satılan Şişe Suları İle Musluk Sularının Ağır Metal Düzeylerinin İncelenmesi(2017) Bolu, Filiz; Mayda, Atilla Senih; Poyraz, Bayram; Yılmaz, MuammerAmaç: Bu çalışmada şişelenmiş kaynak suları ile Düzce şebeke suyunun ağır metal içeriği açısından karşılaştırılması amaçlanmıştır. Yöntem: Musluk suyunu analiz etmek için belirlenen 14 ayrı noktadan aynı tarihte numune alınmıştır. Ticari doğal kaynak suyu numuneleri 500 ml pet şişelerde satışa sunulan 10 farklı markadan alınan örneklerdir. Su örneklerindeki ağır metal değerleri; Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) cihazı ile ölçülmüştür. Sonuçlar ABD Çevre Koruma Ajansı (EPA), Dünya Sağlık Örgütü (DSÖ) ve T.C. Sağlık Bakanlığı tarafından önerilen kriterlere göre değerlendirilmiştir. Bulgular: Alınan musluk suyu ve ticari su numunelerinde ağır metal düzeyleri DSÖ, EPA ve T.C. Sağlık Bakanlığı'nın önerdiği limit değerlerden düşük bulunmuştur. Ticari su ağır metal düzeyi ortalaması ile musluk suyu örneklerinin ağır metal düzeyi ortalaması karşılaştırıldığında bor (B), alüminyum (Al), krom (Cr), mangan (Mn), demir (Fe), nikel (Ni), arsenik (As), stronsiyum (Sr), molibden (Mo), kadmiyum (Cd), civa (Hg) ve kurşun (Pb) düzeyleri ticari su numunelerinde musluk sularına göre istatistiksel olarak anlamlı düzeyde düşük bulunmuştur. Sonuç: Ağır metal düzeyleri açısından musluk suyu ve ticari şişe sularının içilmesinde bir sakınca bulunmadığı görülmektedir.Öğe Düzce’de Satılan Şişe Suları İle Musluk Sularının Ağır Metal Düzeylerinin İncelenmesi(Duzce Univ, 2017) Yılmaz, Muammer; Bolu, Filiz; Mayda, Atilla Senih; Poyraz, BayramAmaç: Bu çalışmada şişelenmiş kaynak suları ile Düzce şebeke suyunun ağır metal içeriği açısından karşılaştırılması amaçlanmıştır. Yöntem: Musluk suyunu analiz etmek için belirlenen 14 ayrı noktadan aynı tarihte numune alınmıştır. Ticari doğal kaynak suyu numuneleri 500 ml pet şişelerde satışa sunulan 10 farklı markadan alınan örneklerdir. Su örneklerindeki ağır metal değerleri; Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) cihazı ile ölçülmüştür. Sonuçlar ABD Çevre Koruma Ajansı (EPA), Dünya Sağlık Örgütü (DSÖ) ve T.C. Sağlık Bakanlığı tarafından önerilen kriterlere göre değerlendirilmiştir. Bulgular: Alınan musluk suyu ve ticari su numunelerinde ağır metal düzeyleri DSÖ, EPA ve T.C. Sağlık Bakanlığı’nın önerdiği limit değerlerden düşük bulunmuştur. Ticari su ağır metal düzeyi ortalaması ile musluk suyu örneklerinin ağır metal düzeyi ortalaması karşılaştırıldığında bor (B), alüminyum (Al), krom (Cr), mangan (Mn), demir (Fe), nikel (Ni), arsenik (As), stronsiyum (Sr), molibden (Mo), kadmiyum (Cd), civa (Hg) ve kurşun (Pb) düzeyleri ticari su numunelerinde musluk sularına göre istatistiksel olarak anlamlı düzeyde düşük bulunmuştur. Sonuç: Ağır metal düzeyleri açısından musluk suyu ve ticari şişe sularının içilmesinde bir sakınca bulunmadığı görülmektedirÖğe Effects of cellulose micro/nanofibers as paper additives in kraft and kraft-NaBH4 pulps(Walter De Gruyter Gmbh, 2016) Tozluoğlu, Ayhan; Poyraz, BayramThis study examined the effects of various CMF/CNFs (microfibrillated and nanofibrillated celluloses) on the relevant properties of paper produced from kraft and kraft-NaBH4 pulps. Subsequent effects of pretreatments on the mechanical, drainage, optical and physical properties of papers obtained from both kraft and kraft-NaBH4 pulps were also studied. Enzymatic pretreatments were accomplished using Celluclast 1.5 L and Pulpzyme HC 2500 enzymes; 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO), phthalimide-N-oxy (PINO) and periodate were utilized in chemical pretreatments. Results showed that the mechanical properties of paper for both kraft and kraft-NaBH4 pulps were improved with the addition of different types of CMF/CNF samples, whereas the sheet drainage was impaired. With 1.5% additions of various CMFs, the kraft pulp and the kraft-NaBH4 pulp displayed increases of 8.32-18.3% and 2.33-8.86% in tensile strength and 6.00-14.0% and 14.0-22.0% in degrees SR, respectively. Compared to other pretreated CMF/CNFs, periodate oxidized-CMF/CNFs significantly affected the properties of papers obtained from both kraft and kraft-NaBH4 pulps. Results also showed that the addition of various CMF/CNFs had a greater effect on the kraft-NaBH4 pulp than on the kraft pulp.Öğe Enzyme treated CNF biofilms: Characterization(Elsevier, 2018) Poyraz, BayramThe objective of this study was to characterize on the chemical, mechanical, electrical and thermal properties of nanofibrillated cellulose based polyvinyl alcohol (PCNF) and silica (SiCNF) films obtained from Pulpzyme HC 2500 and Celluclast 1.5 L enzyme treated kraft-NaBH4 pulps. Morphological alterations were monitored with SEM. Thermal stability, chemical characterization and crystallization were determined using TGA and FT-IR. Young's and storage moduli of the films were determined via a universal testing machine and DTMA. Dielectric properties were evaluated using an impedance analyzer. In the PCNF films, new vibrations and chemical shifts were observed. The crystallinity values of the SiCNF films calculated from the FT-IR were in agreement with the TGA results, revealing that the lowest crystallinity value was in the SiCNF. The higher Young modulus and elongation at break value were obtained in the neat the CNF films while the lowest values were observed in the neat SiCNF films. However, the SiCNF films revealed higher thermo-mechanical property. The PCNF and SiCNF films exhibit more visible dielectric behavior than that of the neat CNF films. Higher thermal stability, thermo-mechanical and mechanical properties were determined in the Pulpzyme HC 2500 enzyme treated films. Hence, this study evidenced that the properties of CNF films having different matrix are influenced by both the enzymes employed. (C) 2018 Elsevier B.V. All rights reserved.Öğe EXAMINING THE EFFICIENCY OF MECHANIC/ENZYMATIC PRETREATMENTS IN MICRO/NANOFIBRILLATED CELLULOSE PRODUCTION(Univ Bio-Bio, 2018) Tozluoğlu, Ayhan; Poyraz, Bayram; Candan, ZekiThere is still a need to improve the production sequences of micro fibrillated and nano fibrillated celluloses to obtain more economic and better quality products. The aim of this study was to improve the production efficiency and quality of micro fibrillated and nano fibrillated celluloses by examining the enzyme (xylanase endo-1,4-) employed in pretreatment sequences. Fairly homogeneous nano fibrillated cellulose with a width of 35 +/- 12 nm was produced in this study. Sequences employed to produce micro fibrillated and nano fibrillated celluloses decreased the cellulose crystallinity of bleached kraft pulp and lower total crystalline index and lateral order index values were observed for micro fibrillated and nano fibrillated celluloses in FTIR examinations. Lower crystallinities were also defined by C-13-NMR (46,2 ppm) which was substantiated with C6 peaks in the amorphous domain. Sequences to produce micro fibrillated and nano fibrillated celluloses resulted in shorter fiber dimensions with less ordered cellulose structure leading lower thermal degradation that reveal main polymer chain source from cellulose units. Dynamic mechanical thermal analysis results showed that the initial and maximum storage modulus of the nano fibrillated and micro fibrillated celluloses films were improved by 114% and 101%, respectively. The storage modulus of micro fibrillated and nano fibrillated celluloses films were 4,96 GPa and 2,66 GPa at temperature of 235 degrees C, respectively.Öğe Filler Type and Particle Distribution Effect on Some Properties of Polymer Composites(2021) Poyraz, Bayram; Eren, Şevki; Subaşı, SerkanThis study reports the effects of silica (S), quartz (Q), and basalt (B) fillers on the chemical, thermal, andmechanical properties of unsaturated polyester (PE) composites. In the study, fillers were selected as sameclass grain distribution and mixed with orthophtalic based PE resin to produce composites. The thermalcharacterization of the composites was determined with thermogravimetric and thermal conductivity.Chemical characterization was carried out with FT-IR. Compressive strength was investigated withUniversal Testing Machine. SEM device was used to investigate the morphological alterations of thecomposites. Also, statistical analysis was carried out for thermal conductivity and mechanical results. Atthe end of the present study, some minor chemical alterations were seen in FT-IR after the interaction ofthe fillers and PE resin. Thermal stability decreased after adding fillers. The thermal conductivity andthermogravimetric analysis were not agreed with each other that higher thermal conductivity was seen inthe PE-Q composites. The compressive strength of filler-based composites was higher than that of the neatPE composite whereas the higher compressive strength was obtained in the PE-Q. This study confirms theapplicability of various fillers as a reinforcing agent in the polymer.Öğe Influence of micro crystalline cellulose on EPDM-based automotive sealing profile(Sage Publications Ltd, 2023) Poyraz, Bayram; Güner, Yusuf; Yardım, Tayfun; Yamanoğlu, Rıdvan; Tozluoğlu, Ayhan; Durmuş, Sefa; Şen, MuratThis study examined the effects of microcrystalline cellulose (MCC) used in EPDM elastomer composites in replace of EPDM. For that purpose, the MCC was added in amounts of 1.75; 3, 5, and 5 , 25 phr to investigate the chemical, thermal, rheological, mechanical, morphological, and dielectric properties of EPDM elastomers. At the end of the study, the MCC enabled increased tensile strength, and elongation while causing lower thermal stability and Mooney scorch. The MCC also facilitated the vulcanization process by providing faster production while mixing homogeneously in the matrix. In addition, it decreased dielectric lossyness as well as increased the electric charge storage capacity. However, E-Cel2, containing 3, 5 phr MCC, was found to be more suitable for high-K applications, whereas E-Cel3 was more suitable for low-loss applications. In conclusion, MCC can be also recommended to automotive industries to provide more biocompatible and enhanced properties as a substitute for EPDM.Öğe Influence of Nanofibrillated Cellulose on Mechanical and Thermal Properties of Polyester Composites(2023) Poyraz, Bayram; Eren, Şevki; Subaşı, Serkan; Tozluoğlu, AyhanThis study reports the effects of nano-fibrillated cellulose fillers on the chemical, thermal, and mechanical properties of unsaturated polyester (PE) composites. In the study, the PE was mixed with Nanofibrillated Cellulose (CNF) in the ratios of 0.5, 1, and 1.5 % using Methyl Ethyl Ketone Peroxide (MEKP) and Cobalt octoate (CoOc) as initiator and catalyst, respectively. For characterization, chemical and thermal analyses were carried out with FT-IR and thermogravimetric analysis. Mechanical properties were investigated with Universal Testing Machine, and morphological properties were investigated with SEM. At the end of the study, some minor altered vibrations were seen in FT-IR while thermal stability decreased. The compressive strength of filler-based composites was lower than that of the neat PE composite whereas tensile strength increased. Homogenous dispersion was also seen in the composites. This study confirms the applicability of various fillers as a reinforcing agent in PE resin used in the pipeline sector.Öğe Influence of PVA and silica on chemical, thermo-mechanical and electrical properties of Celluclast-treated nanofibrillated cellulose composites(Elsevier Science Bv, 2017) Poyraz, Bayram; Tozluoğlu, Ayhan; Candan, Zeki; Demir, Ahmet; Yavuz, MustafaThis study reports on the effects of organic polyvinyl alcohol (PVA) and inorganic silica polymer on properties of Celluclast-treated nanofibrillated cellulose composites. Nanofibrillated cellulose was isolated from Eucalyptus camaldulensis and prior to high-pressure homogenizing was pretreated with Celluclast enzyme in order to lower energy consumption. Three nanocomposite films were fabricated via the casting process: nanofibrillated cellulose (CNF), nanocellulose-PVA (CNF-P)and,nanocellulose-silica (CNF-Si). Chemical characterization, crystallization and thermal stability were determined using FT-IR and TGA. Morphological alterations were monitored with SEM. The Young's and storage moduli of the nanocomposites were determined via a universal testing machine and DTMA. The real and imaginary parts of permittivity and electric modulus were evaluated using an impedance analyzer. The crystallinity values of the nanocomposites calculated from the FT-IR were in agreement with the TGA results, showing that the lowest crystallinity value was in the CNF-Si. The CNF-P displayed the highest tensile strength. At a high temperature interval, the storage modulus of the CNF-Si was greater than that of the CNF or CNF-P. The CNF-Si also exhibited a completed singular relaxation process, while the CNF and the CNF-P processes were uncompleted. Consequently, in terms of industrial applications, although the CNF-P composite had mechanical advantages, the CNF-Si composite displayed the best thermo-mechanical properties. (C) 2017 Elsevier B.V. All rights reserved.Öğe Influence of wax content on the electrical, thermal and tribological behaviour of a polyamide 6/graphite composite(Walter De Gruyter Gmbh, 2016) Ünal, Hüseyin; Kaya, Uğur A.; Esmer, Kadir; Mimaroğlu, A.; Poyraz, BayramIn this study, the influence of wax content on the electrical, thermal and tribological properties of a polyamide 6 composite filled with 15% wt. graphite was investigated. The wax filler contents of the composite were by 2, 4 and 6 wt.%. Characterisation of the composites was obtained using a Fourier transform infrared spectroscopy test. Electrical performance tests were carried out, and the dielectric real values (epsilon') and imaginary values (epsilon '') were recorded. Thermal differential scanning calorimetry tests were carried out, and the glassy and melting temperatures of the composite materials were recorded. Furthermore, tribological tests were carried out and the friction coefficient and wear rate of the composites were recorded. The results show that the increase in wax content led to the increase in the permittivity values (epsilon' and epsilon '') of the composites. The increase in wax content also led to the decrease in the friction coefficient and wear rates of the composite materials. Furthermore, the glassy and melting temperatures of the composite materials showed a sensitivity to the wax content. Finally, it is concluded that optimum properties, in total, were obtained in the composite filled with 6 wt.% wax.Öğe Kompozit malzeme üretiminde kullanılan polyesterlerin mekanik, termal ve kimyasal özelliklerine başlatıcı etkisinin incelenmesi(Gazi Univ, Fac Engineering Architecture, 2018) Eren, Şevki; Poyraz, Bayram; Gökçe, Neslihan; Şamandar, Ayhan; Aykanat, Batuhan; Subaşı, SerkanBu çalışmada farklı oranlarda başlatıcı kullanılarak, kompozit malzeme üretiminde kullanılan polyesterlerin fiziksel, kimyasal, termal ve mekanik özellikleri incelenmiştir. Çalışma kapsamında, izoftalik ve ortoftalik polyester reçineleri kullanılmıştır. Reçinelerin içerisine %1,0, %1,5, %2 ve %2,5 (v/v) oranlarında metil etil keton peroksit (MEKP) başlatıcı olarak ilave edilirken, %1,0, oranında da kobalt oktoat (C16H30CoO4) reaksiyon hızını ve verimini artırmak için katalizör olarak ilave edilmiştir. Çalışmada fiziksel özellikleri belirlemek için jelleşme sıcaklığı, jelleşme süresi, pik ekzoterm sıcaklığı ve viskozite analizleri yapılmıştır. Kompozitlerin termal kararlılığı termogravimetrik (TGA) analizler ile belirlenmiştir. Polimerizasyon sonucundaki moleküler etkileşimleri incelemek için FT-IR cihazı kullanılmıştır. Çekme dayanımı, çekme Emodülü, eğilme dayanımı ve eğilme E-modülünü belirlemek için Universal test cihazı kullanılmıştır. Sonuç olarak; başlatıcı oranının kompozitlerin mekanik özelliklerini etkilediği gözlenmiştir. Başlatıcı oranı ve mekanik özellikler arasındaki ilişki incelendiğinde ise, izoftalik reçineden oluşan kompozitlerin mekanik dayanımlarının, ortoftalik reçineden oluşan kompozitlerden genel olarak daha yüksek olduğu belirlenmiştir. Dayanım değerleri açısından ise optimum başlatıcı oranının izoftalik ve ortoftalik reçineden elde edilen kompozit için %1 olduğu görülmüştür.Öğe Lignin in Place of Carbon Black for Ethylene-Propylene-Diene-Monomer Based Automotive Sealing Profiles(North Carolina State Univ Dept Wood & Paper Sci, 2022) Poyraz, Bayram; Güner, Yusuf; Tozluoğlu, Ayhan; Yamanoğlu, Rıdvan; Candan, Zeki; Şen, MuratThis study examined the effects of lignin used in EPDM elastomer composites in place of carbon black. For that purpose, lignin was added in amounts of 3.5, 7, and 10.5 phr to investigate the chemical, thermal, rheological, mechanical, and morphological properties of the EPDM elastomers. At the end of the study, tear strength and elongation were enhanced, whereas thermal stability was lowered due to the lignin. The lignin facilitated the vulcanization process and improved the torque values. In the morphology, the lignin was dispersed homogeneously in the matrix, and no voids or cracks were observed except with 10.5 phr. In conclusion, when incorporated at a specified ratio, lignin is economical and provides ecological benefits. Its use as a natural filler can be recommended to automotive industries to provide enhanced properties and ecological properties as a substitute for carbon black.Öğe Matrix impact on the mechanical, thermal and electrical properties of microfluidized nanofibrillated cellulose composites(Walter De Gruyter Gmbh, 2017) Poyraz, Bayram; Tozluoğlu, Ayhan; Candan, Zeki; Demir, AhmetThis study reports on the effect of organic polyvinyl alcohol (PVA) and silica matrix on the properties of cellulose-based nanocomposites. Nanofibrillated cellulose was isolated from kraft pulp and treated with Pulpzyme HC 2500 enzyme prior to high-pressure homogenization in order to lower energy consumption. Three nanocomposite films were fabricated via the casting process: nanofibrillated cellulose, nanocellulose-PVA (NC-PVA) and nanocellulose-silica (NC-Si). Chemical characterization and crystallization were determined with FTIR. Thermal stability was investigated with thermogravimetric analysis. Morphological alterations were monitored with scanning electron microscopy. A universal testing machine and dynamic mechanical thermal analysis were used for determination of Young's and storage moduli. The real and imaginary parts of permittivity and electric modulus were evaluated using an impedance analyzer. Considerable alterations were seen under FTIR. Thermal stability was lower in NC-Si than in NC-PVA due to lower crystallinity. Higher Young's modulus and storage moduli were observed in NC-PVA than in NC-Si. NC-PVA exhibited a singular relaxation process, while a double relaxation process was seen in NC-Si. Consequently, the nanocomposite film prepared from the organic matrix (NC-PVA) had a mechanical advantage for industrial applications. However, neat NC composite revealed the highest storage modulus and thermal stability.Öğe Mesopore silica effect on chemical, thermal and tribological properties of polyimide composites(Walter De Gruyter Gmbh, 2022) Poyraz, Bayram; Ünal, Hüseyin; Dayı, MustafaIn this experimental study, the effects of mesoporous silica filler content on the chemical, thermal and tribological properties of polyimide composites were investigated. For that purpose, Pi/mesoporous silica composites were produced by in situ polymerization with various mesoporous silicas. After fabrication, thermal stability and chemical characterization were determined using TGA and FTIR. Morphological alterations were monitored with a scanning electron microscope (SEM). Texture structure (pore size and pore volume) were determined by the BJH method. Friction and wear properties were investigated by using a pin-on-disc arrangement. At the end of the study, minor shifts of Pi/mesoporous silica composites were observed. Thermal stability, as well as pore size and pore volume, was decreased with mesoporous silica. The coefficient of friction and specific wear rate decreased with the addition of mesoporous silica. Abrasive wear behaviors were seen for both neat Pi and Pi-Si composites. Hence, this study evidenced that the properties of Pi are influenced by mesoporous dimensions and content of Si employed.