Papers by M.Özgür Seydibeyoğlu
Journal of Applied Polymer Science, Apr 9, 2012
Recyclability of the bioplastic polyhydroxybutyrate-co-valerate (PHBV) was studied with multiple ... more Recyclability of the bioplastic polyhydroxybutyrate-co-valerate (PHBV) was studied with multiple melt processing (five cycles), with their performances evaluated. A batch of PHBV was processed with a twin screw extrusion followed by injection molding. This operation was repeated five times and samples were collected from each cycle for characterization. For each cycle, the mechanical properties were characterized with tensile, flexural, and impact testing, along with dynamic mechanical analysis. The results showed that the mechanical properties are maintained for four cycles; but in the fifth cycle, there was slight decrease in the properties. Gel permeation chromatography studies revealed that the molecular weight of the polymer does not decrease drastically; however, a drop was observed after third, fourth, and fifth cycle (8.7% decrease after third cycle, 13.5% decrease after fourth cycle, and 16.6% decrease after fifth cycle). The differential scanning calorimeter showed that the glass transition and melting temperatures did not change upon reprocessing, but the degree of crystallinity was reduced as a consequence of melt processing. The thermal gravimetric analysis showed that the onset value of thermal decomposition decreased very slightly. It was observed by Fourier transform infrared spectroscopy that the chemical structure of PHBV was maintained without any side chain reaction during processing. Scanning electron microscopy studies from the fractured surfaces of Cycles 1 and 5 confirmed that the uniformity of PHBV surfaces was maintained after five cycles, coinciding with the mechanical tests. The density measurements revealed that there was no change in the density of PHBV. V
International Journal of Plastics Technology, Jun 1, 2010
In this study, the impact strength and elongation properties of a bacterial biopolymer, polyhydro... more In this study, the impact strength and elongation properties of a bacterial biopolymer, polyhydroxyutyrate-co-valerate (PHBV) co-polymer were improved with different functionalized vegetable oils, and nano structured Polyhedral Oligomeric Silsesquioxane (POSS). PHBV was blended with functionalized oils, epoxidized linseed oil, epoxidized soybean oil, and epoxy soyate using twin screw melt processing, and samples for testing were prepared by injection molding. PHBV was also blended with POSS and blend of PHBV with and without epoxy soyate were also prepared. The materials were characterized by impact strength testing, tensile testing, dynamic mechanical analysis, differential scanning calorimetry, and scanning electron microscopy studies. The studies showed that the impact strength was improved 92% with the epoxy soyate, which is a chemically modified version of epoxidized soybean oils by reaction with alcohols. The impact strength was further improved (120%) compared to neat PHBV synergistically with the addition of POSS to PHBV-epoxy soyate blend. With the addition of POSS to the PHBV-epoxy soyate system, elongation was improved 105%. It was also observed that with the addition of functionalized oils and POSS, the melting temperature of the PHBV was reduced more than 10°C which is very important for the processing of PHBV.
Scientific Reports, Aug 6, 2020
Carbon, Jun 1, 2019
Abstract A screen-printed electrode-based electrochemical sensor modified with graphene reinforce... more Abstract A screen-printed electrode-based electrochemical sensor modified with graphene reinforced nanofibers for the determination of acetaminophen was fabricated by electrospinning, thermal stabilization, and carbonization. Abundant and inexpensive biopolymer lignin was blended with polyacrylonitrile (PAN) and graphene (GRP) to obtain the deformity-free and an average diameter 105 nm nanofibers (Lignin/PAN/GRP:85/15/1 wt %). The electrospinning process of nanofibers is optimized by the Design of Experiments statistical programme and rheometry were performed. When carbonized at 900 °C, Lignin/PAN/GRP carbon nanofiber presents carbon content of these carbon nanofibers amounts to 94.3% measured by Energy Dispersive X-ray Spectroscopy and we statement the transformation of carbon nanofibers with average diameter less than 100 nm and the graphene sheets improved the degree of graphitization of carbon nanofibers. In this work, the electrochemical characterization of carbon nanofiber (CNF) and graphene reinforced carbon nanofiber (CNF-G) modification onto the screen-printed electrode (SPE) has been verified via Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), and the electrochemical response of acetaminophen of modified electrode was detected by Differential Pulse Voltammetry (DPV). The results revealed that the modified electrodes showed a marked electrochemical activity with a remarkable improvement in conductivity and in response to acetaminophen compared to the bare electrode.
In this paper, a new blending method for Graphene nanoplatelets was developed. A chaotic system b... more In this paper, a new blending method for Graphene nanoplatelets was developed. A chaotic system based robust delta robot was designed. Both the speed of the mixer motor and position of the propeller were chaotically changed. Performance of the systems was evaluated by a material analysis method. The results showed that the proposed method has a better performance than statically mounted mixers.
Robotics and Autonomous Systems
This paper presents the design, implementation and polymer nanocomposite mixing application of a ... more This paper presents the design, implementation and polymer nanocomposite mixing application of a robust spatiotemporal chaotic delta robot. Blending fluids efficiently is a vital process for the preparation of graphene nanocomposite mixing. The most commonly used mixing materials are polymeric materials that need to be blended in non-Newtonian fluids. To achieve a superior blending performance over the conventional ones, it is used two different chaotification mechanisms for the realization of the spatiotemporal chaotic delta robot mixer system. One of them is for the chaotification of the mixer propeller while the second one is for the chaotification of the three-dimensional position of the endpoint of the delta robot. The model-based robust chaotification scheme based on sliding mode control is applied to chaotify the speed of the delta robot-mixer via dynamical state-feedback chaotification method. The chaotification of 3D position of the mixer is realized in a feedforward way by producing chaotic input signals. The implemented robust chaotic delta robot mixer exploits the efficacy of chaotic mixing in obtaining homogeneity in the mixture with less operation time, and hence reduced electrical energy consumption. In these performance evaluations, energy consumption and material characterization, which are measured by reliable material characterization methods such as X-ray diffraction, Fourier-transform-infrared spectroscopy, water contact angle, dynamical mechanical analysis, atomic force microscopy, Raman and field emission-scanning electron microscope analyses, are used as criteria. The obtained results show that, for the delta robot, the proposed chaotic-speed together with 3D chaotic-movement operation mode provides a better mixing performance than other mixing operation modes.
Sustainable Lignin for Carbon Fibers: Principles, Techniques, and Applications, 2019
In recent decades, carbon fibers (CFs) have attracted attention for their potential use as struct... more In recent decades, carbon fibers (CFs) have attracted attention for their potential use as structural materials in sports, cars, aerospace, and bridges. Also, carbon fibers have been considered as the next-generation materials in the aviation industry, which have presented an enormous chance for the entire supply chain of carbon fibers. However, they are having inert surface and do not allow matrix material to make bonding with it. For this reason, the surface treatment of carbon fibers is one of the advised methods to develop adhesion between the two. So, good adhesion between the carbon fiber and the matrix must be supplied in order to maximize performance. In this chapter, we will introduce the brief overview of surface treatment for carbon fibers based on lignin showing superior performance and developing processability. Surface treatment, for lignin-based carbon fibers, is discussed primarily to identify the mechanism of interphase formation. The objective of this chapter is to review numerous methods used for the surface treatment of carbon fibers and to provide details on mechanical, chemical, and morphological changes happen in carbon fiber properties. It will also be presented that mainly used surface treatment methods are chemical, dry, and nano-surface treatments. Comparative study of these different methods helps in the selection of suitable surface treatment method in accordance with the requirement. Selecting appropriate surface-treatment methods might modify the carbon fiber surface through increasing the surface functional groups and surface area. Additionally, they can modify the carbon fiber surface with increasing the electro properties components on the surface for supplying the carbon fiber-matrix interactions.
Hacettepe Journal of Biology and Chemistry
Reinforcement of polymer matrix with natural fiber can provide an increase in mechanical properti... more Reinforcement of polymer matrix with natural fiber can provide an increase in mechanical properties of the related composite. Since thermoplastics, especially bio composite materials are recyclable, they contribute to a sustainable ecosystem. In this study, 10% by weight hemp reinforced polylactic acid (PLA) matrix compounds were produced. Tensile test specimens were performed in two different infill patterns, parallel and +/- 45° cross, using the Fused Filament Fabrication (FFF) method from the developed bio composite filaments. Ultimate tensile stress increases approximately 20%. It has been observed that the geometry of the infill pattern greatly affects the tensile strength. In addition, through optical and scanning electron microscopy (SEM) the the produced composite filaments were examined. Surface interactions and homogeneous fiber distribution between PLA and hemp were investigated. As a result, hemp is used as a reinforcement material in related studies, its homogeneous dis...
Polymers
In this study, recycled and commercial Ti6Al4V powder was added to polyester composites at variou... more In this study, recycled and commercial Ti6Al4V powder was added to polyester composites at various filling ratios by weight fraction. Three weight fractions of Ti6Al4V particles, 0%, 5%, and 10%, were chosen for study. By examining the mechanical and microstructural properties of polyester composites, the effects of the Ti6Al4V powder proportion by weight fraction and particle size parameters were investigated. With the filler loading, a 39% increase in the tensile strength of the composites was achieved. A minor decrease in flexural strength was observed at 5% filler weight fraction. The addition of the recycled Ti6Al4V powder to the polyester matrix slightly reduced the thermal conductivity of the composite over that of the neat polymer. However, the incorporation of the commercial Ti6Al4V powder fillers in the polyester matrix considerably increased the thermal conductivity of the composites, suggesting several potential uses. The presence of high levels of oxygen in the powder l...
Journal of Applied Polymer Science, 2009
The natural clay, HEC, was taken from the region of Eskisehir of Turkey. The natural clay, MMT, w... more The natural clay, HEC, was taken from the region of Eskisehir of Turkey. The natural clay, MMT, was taken from Bigadic, Balıkesir region of Turkey. They were analyzed both by chemically and by mineralogically (Table I). The purities of HEC and MMT were determined to be 90 ...
Turkish Journal of Forestry, Jul 9, 2019
The influence of coupling agents on mechanical properties of lignin-filled polypropylene composites.
Research on engineering structures & materials, 2023
Makine Teknolojileri Elektronik Dergisi (elektronik), 2013
Elyaf takviyeli polimerik kompozit malzemelerde arayüzey mekaniğinin iyileştirilmesi, kompozitin ... more Elyaf takviyeli polimerik kompozit malzemelerde arayüzey mekaniğinin iyileştirilmesi, kompozitin mukavemeti açısından büyük önem taşımaktadır. Arayüzey mekaniği doğrudan elyaf ile reçine arasındaki mekanik tutunma ve kimyasal bağlanma ile ilgilidir. Bu çalışmada, karbon elyaf takviyeli epoksi kompozitlerin arayüzey dayanımına etki eden kimyasal bağlanma performansı, nanoteknolojik yöntemler ile arttırılmaya çalışılmıştır. Bu kapsamda polimerik reçine içine kütlece %0,1 oranında takviye edilen, iki ayrı kimyasal işlem görmüş "Grafen" bazlı nanopartiküller (GO) ile modifiye epoksi sistemler oluşturulmuş ve film kompozit-prepreg-üretim yöntemi ile karbon elyaf takviyeli epoksi nanokompozitler üretilmiştir. Reçine modifikasyonu ile yüzey gruplarına sahip grafen nanopartikülleri, epoksi polimeri içinde tutunabilmiş ve tabakalararası kayma mukavemeti (ILSS) değerinde en yükseği %58 olmak üzere ciddi artışlar sağlanarak kompozitin arayüzey dayanımı arttırılmıştır.
Cellulose, 2018
This study addresses the modification and characterization of Conium maculatum fiber to enhance i... more This study addresses the modification and characterization of Conium maculatum fiber to enhance its usability as reinforcement in polymeric composite materials. The fibers were treated with alkali, silane, potassium permanganate, potassium dichromate and silicone oil, then surface chemistry (fourier transform spectroscopy and X-ray photoelectron spectroscopy), thermal stability (thermogravimetric analysis) and morpho-structure (X-ray diffraction and scanning electron microscopy) of the fibers were characterized by instrumentally. It was determined that the treatments increased hydrogen bond index and oxygen/carbon atomic ratio of the fibers. Alkali treatment had a positive impact on crystallinity index of the fiber by improving crystallite packing order following partial removal of noncellulosic agents. The oxidation agents and the silane coupling agent reduced the crystallinity index of the fiber as a result of opening of glucopyranose rings and the increments in the distance between the cellulose macromolecular chains, respectively. Thermal degradation temperatures of the fiber were improved after treatment and the fiber presented rougher surface after treatments that can be an advantage when used as reinforcement to enhance mechanical strength of the final composite.
In this study, polyurethane-carbon fiber composites were prepared with excellent interface with p... more In this study, polyurethane-carbon fiber composites were prepared with excellent interface with perfect adhesion of carbon fibers with the polyurethane matrix. The polyurethane was thermoplastic polyurethane and the carbon fiber was polyacrylonitrile based with 7 micron meter thickness. The composites were prepared with solvent casting technique. The composite materials were characterized with tensile testing, dynamic mechanical analysis, scanning electron microscope, and thermogravimetric analysis. The excellent adhesion of the carbon fibers in the polyurethane matrix was observed with scanning electron microscopy investigations. This adhesion creates huge improvements in the mechanical properties of the polyurethane. 300 % improvement in tensile strength was achieved with very low percentages of the carbon fiber such as 3 wt %. The hydrophilicity of the polyurethane matrix was confirmed with water contact angle measurements that led to better interaction.
Applied Science and Engineering Progress
The transportation industry with airways, road transportation, shipping, and railways is a huge m... more The transportation industry with airways, road transportation, shipping, and railways is a huge market for composites both military and civil applications. The need for sustainable and lightweight solutions triggered the need for composite materials. There are many different approaches for composite materials design and manufacturing to optimize the properties in strength, acoustic, and many more like such as ballistic, thermal management, and so onetc. The use of various reinforcing elements for various resins created endless options for materials scientists and designers. Among a variety of possibilities, the use of hybrid reinforcement has been quite a new approach for the composites, which is analogous to composite to optimize the performance of the final properties, such as impact, ultimate tensile strength, modulus value, thermal properties, and other properties. In this review article, the future of the transportation sectors, the advantages of railway transportation in this ...
CRC Press eBooks, Jun 23, 2022
Nanoparticle-Based Polymer Composites
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Papers by M.Özgür Seydibeyoğlu