Search

Polimer kompozitlerde matris malzemesi olarak termoplastikler daha yaygın olsa da epoksi ve polyester gibi termosetlerin kullanımı da mevcuttur. Bu çalışmanın amacı, endüstride yaygın bir şekilde kullanılan polyester reçinesi içerisine kalsit ilavesinin yanı sıra doğal bir atık malzeme olan çam talaşını ilave ederek üretilen kompozit numunelerin aşınma özelliklerini incelemektir. Kalsit (kalsiyum karbonat), inorganik dolgu maddesi olarak endüstride yoğun kullanıma sahiptir. Çam talaşı ise özellikle mobilyacılık sektöründe doğal atık olarak çıkmaktadır. Bu iki dolgu malzemesi matrise farklı oranlarda ilave edilmiştir. Elde edilen karışım açık teflon kalıba dökülerek kompozit numuneler hazırlanmıştır. Numunelerin 22 saat suda bekletilmesiyle su absorbsiyonu, pin on disk yöntemi uygulanarak aşınma özellikleri ve Shore D yöntemiyle sertlik özellikleri incelenmiştir. Kırık yüzeyler için SEM analizi yapılmıştır. Aşınma testi sonuçları talaş miktarının artmasıyla aşınmanın arttığını, kalsit miktarının artmasıyla aşınmanın azaldığını göstermiştir. Shore D sertlik testinde ise özellikle kalsit miktarının artışına bağlı olarak sertliğin arttığı görülmüştür. Su absorbsiyon testinde ise kompozit numunelerde kalsitin azalması ve talaş oranının artmasıyla su absorbsiyonunun arttığı gözlenmiştir.

Kompozit rezinler günümüzde anterior dişlerin restorasyonlarında uygulandığı gibi posterior dişlerin restorasyonlarında da gittikçe artan bir kullanım alanına sahiptir. Civa içeren restoratif materyallerin hastalarda tedirginliğe sebep olması ve estetik restorasyonlara artan ilgi kompozit rezin restorasyonlara olan talebin artmasına neden olmaktadır. Geleneksel kompozit rezinlerin tabakalı olarak yerleştirilme gerekliliği hem tedavi süresini uzatmakta hem de teknik hassasiyetin gerekliliğini artırmaktadır. Bu gibi dezavantajların önüne geçebilmek amacıyla 4-5 mm kalınlıkta tek bir tabakayla yerleştirmeye imkân sağlayan bulk fill kompozit rezinler piyasaya sürülmüştür. Bulk fill kompozit rezinlere ışık uygulanması sırasında ışığın daha derin kısımlara nüfuz edebilmesi materyalin ışık geçirgenliğinin artırılmasıyla sağlandığından estetik açıdan problem oluşturmaktadır. Materyal yapısında bazı güncellemeler yapılarak bu problemin önüne geçilmeye çalışılmaktadır. Bulk fill kompozit rezinler viskozitelerine göre; yüksek viskoziteli bulk fill kompozit rezinler ve akışkan bulk fill kompozit rezinler olmak üzere ikiye ayrılırlar. Akışkan bulk fill kompozit rezinlerin düşük mekanik özellikleri sebebiyle geleneksel bir kompozit rezinle örtüleme yapılması önerilmektedir. Bu derlemenin amacı restoratif diş hekimliğinde kullanılan bulk fill kompozit rezinler ile ilgili güncel literatür bilgilerinin sunulmasıdır.

There is great interest in using natural materials in production, and this is due to ecological concerns. The two main pillars in developing natural composites are waste utilization and ensuring good economic returns. The biodegradability of natural fillers is one of the factors in expanding their use in natural fiber-reinforced composites. Naturally added composites, which are effectively used in different applications such as automotive, aviation, and maritime as well as design and construction industries, offer improved mechanical and tribological properties to the material. In the study where the mechanical effects of natural additives on the polymer were examined, waste banana peel powder and rice peel powder were added to polypropylene at different concentrations. After melt mixing of the components forming the composite, injection molding was performed. To determine the mechanical properties, tensile, hardness, Izod impact strength and density tests were carried out, and the microstructure examination of the composites was carried out with a scanning electron microscope. As a result of the studies, adding natural additives to the polymer caused the impact properties, elongation amount and tensile strength to deteriorate. In addition, with the increase in the reinforcement ratio, the density, hardness and elastic modulus of polymer composites increased. [ABSTRACT FROM AUTHOR]

In the present study, wear and friction behavior of Al6061-based composites reinforced with carbon nanotube (0.1, 0.3, 0.5wt.%) fabricated via the powder metallurgy and hot-pressing were investigated. Production process consists of the process steps of mixing powders, filtering, drying, pressing, sintering and hot pressing. The wear and friction behavior of the produced samples were examined with the help of a pin-on-disc wear test device. The worn and fracture surfaces of the samples were researched by scanning electron microscopy. As a result of the tests conducted, the highest hardness value (118 HV), minimum wear rate (5.1×10-7 mm³ /(Nm)), and minimum mass loss (0.0033 g) were obtained in the Al6061-0.1%carbon nanotube composite structure. It was determined that the hardness and wear rate of the Al6061- 0.1%carbon nanotube improved by 10.2% and 17.6% compared to the Al6061 alloy. It has been determined that carbon nanotube reinforcement up to 0.1wt.% amount improves the tribological properties of Al6061 matrix composite. Hardness and wear rate of the composite were decreased due to the clustering of carbon nanotube after 0.1wt.% reinforcement ratio. [ABSTRACT FROM AUTHOR]

Copyright of Informacije MIDEM: Journal of Microelectronics, Electronic Components & Materials is the property of MIDEM Society 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.)

In parallel with technological developments, the need for affordable, functional and sustainable materials is increasing day by day. At this point, wood composite materials, which provide many economic and environmental advantages compared to traditional polymer matrix composites, attract great interest due to their functionality in a variety of engineering applications. In this study, the structural properties of functional wood plastic composites were examined before the sustainability analysis and the current market analysis was made by evaluating the usage areas of these materials Furthermore, information about these materials' production methods is presented, and approaches for improving material properties are evaluated. The literature review compiled integrated information on the recent progress of these composites and the development of material properties. Thus, by emphasizing the importance of wood-plastic composite materials in terms of sustainability, it is aimed to provide researchers with a basis for the structural properties, production technologies and sectoral trends of these materials. [ABSTRACT FROM AUTHOR]

Copyright of Turkiye Klinikleri Journal of Dental Sciences is the property of Turkiye Klinikleri 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.)

Copyright of Gazi Üniversitesi Fen Bilimleri Dergisi Part C: Tasarım ve Teknoloji is the property of Gazi University 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.)

Copyright of Current Research in Dental Sciences is the property of Ataturk University Coordinatorship of Scientific Journals 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.)

Background: Aim of this study is to assess the color matching in class III restorations made with single-shade resin composite after bleaching with different carbamide peroxide concentrations. Methods: In this study, 20 human incisors that were free of caries or enamel abnormalities and freshly extracted for periodontal or orthodontic reasons were cleaned of blood, debris, and calculus. Mesial and distal surfaces were restored with single-shade composite (Omnichroma, Tokuyama, Japan). All samples were randomly divided into two groups, all of the mesial surfaces were isolated, and distal surfaces were coated with %10 and %15 carbamide peroxide (Opalescence PF; Ultradent Products, Inc, USA). Polishing discs (Zenit Flex, President Dental, Germany) were used the composite restoration. Color matching was evaluated on photographs with a digital colorimeter. SPSS software program was used to perform statistical analysis (IBM Corp., Armonk, NY, USA). Results: Statistically significant difference was found between the color matching of the restorations after the 5th treatment with 15% carbamide peroxide (p = 0.004), and at the end of 10th treatment with 10% carbamide peroxide (p = 0.028). Depending on the carbamide peroxide concentration, after the 5th treatment a statistically significant difference was found between 15% and 10% carbamide peroxide (p = 0.000), but no statistically significant difference after the 10th treatment (p > 0.05). Conclusions: After carbamide peroxide bleaching, hard tissue color became lighter. Since there is no color pigment in single-shade composites, color might be lighter after bleaching. Therefore, these composites may be considered safer in bleaching. Keywords: Bleaching, Color Match, Composite

The use of fillers in fiber-reinforced epoxy matrix composites to enhance the wear performance of the composite is a widely employed method nowadays. In this study, the effect of incorporating graphite filler into a glass fiber-reinforced composite structure on the tribological properties of the composite was investigated. Composite materials produced using the hand lay-up method with three different levels of graphite filler were compared to unfilled composites in terms of wear behavior under different loads (7 N, 10 N, 15 N) and sliding distances (200 m, 400 m). The influence of load, filler content, and sliding distance on the friction coefficient and wear rate was discussed. When the results are examined, the significant effects of graphite filler on wear volume and friction coefficient are clearly observed. In the composite containing 12% graphite, the wear volume has decreased by almost 96%; this ratio has been around 93% for the composite with 4% graphite filler. As the reinforcement of graphite and force increase, the friction coefficient decreases, whereas with the increase in sliding distance, the friction coefficient declines. Microstructural analysis revealed that the filled composites exhibited less abrasion compared to the unfilled composites, and the surface porosity and craters were shallower.

Eco-friendly materials receive more attention due to the necessity of addressing pollution and resource depletion in the face of exponential industrial expansion. Natural fibers provide a sustainable substitution, especially in green composites. This study investigated the feasibility of Allium fistulosum L. (Scallion) as a fiber resource for composite applications by using its tassel. Allium fistulosum L. is derived from a widely available plant and its waste tassels of the plant provide fiber properties and have the potential to be a reinforcing component in composites. The investigation involves characterizing Allium fistulosum L. (AfL) fibers through various analyses. The density of the AfL was determined approximately 1.35 – 1.45 g/cm3. The percentages of lignin, hemicellulose, and cellulose were found to be 24.31%, 29.73%, and 38.36%, respectively. FTIR and XRD analysis affirm AfL's cellulose, hemicellulose, and lignin presence. SEM images indicate a rough surface, necessitating modification for better matrix compatibility. TGA shows suitable thermal stability, majorly degrading beyond 267°C. Tensile testing demonstrates a tensile strength of 22.19 ±3.75 MPa and 0.87 ±0.16 GPa modulus, exceeding some natural fibers like aerial banyan tree roots and Cordia dichotoma. Results show promising features, indicating the viability of AfL fibers in composites with reduced environmental impact and economic benefits.

Copyright of International Journal of Engineering Research & Development (IJERAD) is the property of International Journal of Engineering Research & Development 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.)

Although thermoplastics are more common as matrix materials in polymer composites, thermosets such as epoxy and polyester are also used. The aim of this study is to investigate the wear properties of composite samples produced by adding pine sawdust, a natural waste material, as well as calcite into polyester resin, which is widely used in the industry. Calcite (calcium carbonate) is used extensively in the industry as an inorganic filler. Pine sawdust is especially produced as a natural waste in the furniture sector. These two fillers were added to the matrix at different rates. The resulting mixture was poured into an open teflon mold and composite samples were prepared. Water absorption was examined by keeping the samples in water for 22 hours, wear properties were examined by applying the pin-on-disc method and hardness properties were examined by using the Shore D method. SEM analysis was performed for fractured surfaces. Wear test results showed that wear increased with the increase in the amount of sawdust and decreased with the increase in the amount of calcite. In the Shore D hardness test, it was observed that hardness increased especially due to the increase in the amount of calcite. In the water absorption test, it was observed that water absorption increased with the decrease of calcite and increase of sawdust ratio in composite samples. [ABSTRACT FROM AUTHOR]

In this study, Si3N4 (1-12% by weight) and graphene (0.15-0.45% by weight) reinforced Al6061 matrix composites were produced by the induction heat treatment and powder metallurgy methods. The density, hardness, compressive strength, wear rate, microstructure, and phase structure of the produced composite materials were investigated, respectively. As a result of the tests performed, the densest microstructure, and the best mechanical/tribological properties were obtained in Al6061-9%Si3N4-0.15%graphene composite structure. As a result of the heat treatment studies, it was determined that the mechanical and tribological properties of the induction hot pressed samples after the sintering process improved by ~15% compared to only sintered samples. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Textiles & Engineers / Tekstil ve Mühendis is the property of Union of Chambers of Turkish Engineers & Architects, Chamber of Textile Engineers 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.)

The purpose of the construction of metal matrix composite materials was to combine the desirable properties of metals and ceramics. Metal matrix composites can be considered as advanced materials that have low weight, high strength, high modulus of elasticity, low coefficient of thermal expansion and suitable abrasion resistance. However, one of the problems with making these composites is the unsuitable wettability of the reinforcing particles in aluminum melt, which creates limitations in the construction of these composites. At first, using the ANFISPSO compound, suitable conditions for casting were investigated and then, using the results, the conditions of the composite in terms of dimensions and weight percent of SiC nano particle, the preheating temperature of the mold and powder, the melt stirring time, the rotation velocity of the impeller and the casting temperature for achieving the desirable properties for casting parts, were determined. According to the results, it can be seen that the use of the Gaussian membership function causes the least error in the training time. Also, the comparison of this model with the experimental results shows the efficiency of this model. [ABSTRACT FROM AUTHOR]

Copyright of Fogorvosi Szemle is the property of Hungarian Dental Association 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.)

Nano-sized PPy/CrOx composite was deposited on a graphite foil (GF) surface using multi-cyclic voltammetry via simultaneous synthesis of PPy and CrOx from an acetonitrile/HBF4/LiBF4/solution containing pyrrole and Cr(BF4)3. The electrochemical properties of the composite were examined using CV and EIS techniques in a Li2SO4 solution, and it was characterized by FESEM, EDX, TEM, and XPS methods. This study revealed that oxygen-deficient CrOx containing Cr(II), Cr(III), and Cr(VI) oxidation states could be synthesized in acetonitrile, unlike in aqueous medium. CrOx with a 6% ratio was encapsulated within the partially oxidized PPy clusters thanks to the simultaneous synthesis of components. The specific capacitance of the PPy/CrOx composite-coated electrode with a mass loading of 4 mg cm-2 was 150 F g-1 at 50 mV s-1, which was higher than that of PPy. Thus, it could be revealed that a small amount of nano CrOx provided a considerable pseudocapacitive contribution to the composite. An asymmetric supercapacitor cell was constructed with PPy/CrOx composite- and PVC/carbon-coated GF electrodes in a polyvinyl alcohol (PVA)/Li2SO4 gel electrolyte. The cell exhibited an energy density of 20.1 Wh kg-1 and a power density of 3.50 kW kg-1 at 5 A g-1. [ABSTRACT FROM AUTHOR]

The use of fillers in fiber-reinforced epoxy matrix composites to enhance the wear performance of the composite is a widely employed method nowadays. In this study, the effect of incorporating graphite filler into a glass fiber-reinforced composite structure on the tribological properties of the composite was investigated. Composite materials produced using the hand lay-up method with three different levels of graphite filler were compared to unfilled composites in terms of wear behavior under different loads (7 N, 10 N, 15 N) and sliding distances (200 m, 400 m). The influence of load, filler content, and sliding distance on the friction coefficient and wear rate was discussed. When the results are examined, the significant effects of graphite filler on wear volume and friction coefficient are clearly observed. In the composite containing 12% graphite, the wear volume has decreased by almost 96%; this ratio has been around 93% for the composite with 4% graphite filler. As the reinforcement of graphite and force increase, the friction coefficient decreases, whereas with the increase in sliding distance, the friction coefficient declines. Microstructural analysis revealed that the filled composites exhibited less abrasion compared to the unfilled composites, and the surface porosity and craters were shallower. [ABSTRACT FROM AUTHOR]

Eco-friendly materials receive more attention due to the necessity of addressing pollution and resource depletion in the face of exponential industrial expansion. Natural fibers provide a sustainable substitution, especially in green composites. This study investigated the feasibility of Allium fistulosum L. (Scallion) as a fiber resource for composite applications by using its tassel. Allium fistulosum L. is derived from a widely available plant and its waste tassels of the plant provide fiber properties and have the potential to be a reinforcing component in composites. The investigation involves characterizing Allium fistulosum L. (AfL) fibers through various analyses. The density of the AfL was determined approximately 1.35 - 1.45 g/cm3. The percentages of lignin, hemicellulose, and cellulose were found to be 24.31%, 29.73%, and 38.36%, respectively. FTIR and XRD analysis affirm AfL's cellulose, hemicellulose, and lignin presence. SEM images indicate a rough surface, necessitating modification for better matrix compatibility. TGA shows suitable thermal stability, majorly degrading beyond 267°C. Tensile testing demonstrates a tensile strength of 22.19 ±3.75 MPa and 0.87 ±0.16 GPa modulus, exceeding some natural fibers like aerial banyan tree roots and Cordia dichotoma. Results show promising features, indicating the viability of AfL fibers in composites with reduced environmental impact and economic benefits. [ABSTRACT FROM AUTHOR]

Buckling phenomenon is a common failure mode for composite materials under the effect of compressive loading which is mainly investigated in two stages as pre – buckling and post – buckling. At the pre – buckling phase, the deformations take place temporarily in elastic range. However, load carrying capacity of a member can be increased by regarding the post – buckling process. Therefore, it is important to determine the final and maximum load carrying ability of the structure. Since, at the end of the post – buckling, the body cannot carry load and crippling failure takes place. In this review article, crippling behavior of the composite structures is investigated. After describing the crippling phenomenon, this study mainly investigates both experimental and theoretical points of views. In this scope, affecting parameters such as stacking sequence, geometrical properties and boundary conditions are determined. Then, the improved theoretical approaches are stated. The compatibilities of the test results are assessed with theoretical studies. [ABSTRACT FROM AUTHOR]

Copyright of Erzincan University Journal of Science & Technology is the property of Erzincan Binali Yildirim Universitesi 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.)

Copyright of Current Research in Dental Sciences is the property of Ataturk University Coordinatorship of Scientific Journals 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.)

Copyright of Selcuk Dental Journal is the property of Selcuk Dental Journal 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.)

The purpose of this work is to improve mechanical properties of rigid polyurethane (RPU) composites used in traditional ceramic casting industry. Therefore, monofilament (mono) and fibermesh (fibril) polypropylene (PP) fibers with various lengths (3, 6, 12 and 18 mm) were incorporated to polymer matrix at different rates (0.5, 1.0, 1.5 and 2% by weight). Effects of fiber type and content on flexural strength, bending strength and compressive strength of composites were investigated. Surface morphology and thermal characteristics of composites were evaluated by SEM and TGA analysis, respectively. Bulk densities of specimens with and without PP fibers vary between 72,15-146 kg/m3. Compared to pure rigid polyurethane foam, bulk density of monofilament PP reinforced composites significantly increased and the highest density value (146,86 kg/m3) was reached in M6/2.0 sample. On the other hand, incorporation of fibrilmesh caused a decrease in bulk density. While the increase in percentage of mono PP increased flexural strength, the presence of fibril PP had a negative effect on strength. Compressive strength of all mono PP reinforced composites is higher than that of pure RPU, except for M6/0.5 sample. Besides, SEM analysis revealed that the presence of PP fibers generally reduced number of closed cells in composite structure. Experimental findings indicate that fiber type, content and length affect mechanical performance of RPU composites. In addition, it is possible to use mono PP fiber reinforced RPU composites as support apparatus in ceramic casting industry.

In this article, the optimum stacking sequence with maximum buckling load factor of a plate made of M91/IM10 unidirectional prepreg material, which has a very high strength compared to the materials used in the aerospace industry, is obtained by genetic algorithm method. The composite plate in question is simply supported at 4 edges and subjected to biaxial in-plane compressive loads. With the computer code developed using the genetic algorithm method, stacking sequences that provide maximum buckling strength at certain fiber angle ranges and certain number of layers for various load cases and various plate aspect ratio combinations are obtained. The laminate is assumed to be symmetrical and balanced. The results are compared with the results obtained from graphite/epoxy composite material, which has been studied in the literature. The comparison reveals that a plate made of M91/IM10 prepreg material can provide the same buckling performance with lighter structures than graphite epoxy. [ABSTRACT FROM AUTHOR]

Bu çalışmada lignoselülozik dolgu maddesi olarak atık gazete kâğıdı lifi, bitkisel atık yağ kullanılmış, polimer olarak da geri dönüştürülmüş polipropilen kullanılmıştır. Atık gazete kâğıdı öğütülüp ve yaklaşık 24 saat boyunca 60˚C˚'de kurutma fırınında bekletildikten sonra %10, %20 ve %30 oranlarında geri dönüştürülmüş polipropilen ile karıştırılmıştır. Atık bitkisel yağ ise %2.5 oranında ilave edilmiştir. Karışımlar 170°C,175°C,180°C,185°C ısı kademelerinde ayarlanmış olan ekstrüzyon makinasına konulmuştur. Ekstrüzyon yöntemiyle üretilen kompozitlerin mekanik ve termal özellikleri belirlenmiştir. Atık gazete kağıdı lifi oranının ilkin eğilme mukavemetini azalttığı, daha sonra ise arttırdığı gözlenmiştir. Termal özelliklerde atık bitkisel yağ kullanımının olumlu etkisi olup ısıl direnci arttırmıştır. DSC analiz sonuçları incelendiğinde, atık gazete kağıdı lifinin kristalenliği arttırdığı sonucuna varılmıştır. Bu çalışma ile tümüyle atık olan bileşenlerin kompozit üretiminde kullanılabilir olduğu ve vaks gibi atık bitkisel yağların kullanılabileceği sonucuna ulaşılmıştır.

In recent years, many different polymer and/or polymer-based composite materials have been used in industrial areas such as machinery, food, textile and aircraft/space industries as machine elements, in bearing cages, felt, gasket and gears. One of these materials is graphite and poly-tetra-fluoro-ethylene (PTFE) filled polyamide-imide (PAI) polymer composite. It can be an alternative to traditional materials such as polyamide, poly-oxy-methylene, poly-ether-ether-ketone with its low expansion coefficient, high strength, high thermal resistance such as 275oC and chemical resistance. In this study, the wear and friction behavior of graphite and poly-tetra-fluorine-ethylene (PTFE) filled polyamide-imide composite were investigated. Wear and friction tests were carried out on a pin-disc tester. The experiments were carried out under constant pressure of 1.06 MPa and at four different speeds (1.0, 2.0, 3.0 and 4.0 m/s). As a result of the experiments, the wear rate, friction coefficient, pin and steel disc surface temperature of the graphite and PTFE filled PAI composite (PAI-Graphite/PTFE) were determined. With increasing sliding speed, the specific wear rate of the composite increased while the friction coefficient decreased. In addition, the composite pin and steel disc surface temperatures increased up to about 46.8 oC. The lowest wear rate of the composite was determined as 2.69x10-15 m²/N, while the highest wear rate was determined as 9.2x10-15 m²/N. The friction coefficient of the PAI-based composite was determined as the lowest 0.31 and the highest 0.36. In addition, the wear surfaces of the composite were examined by optical and scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

Background. Despite the significant increase in the need for energy in the world due to industrialization, high economic growth, modern transport technology systems and the development of the energy sector, due to the limited reserves of oil or fossil fuels, their use is 26-27% of the total need. Therefore, meeting strict standard requirements of fuel quality, using modifiers to obtain high-quality fuel is important in the production of gasoline and diesel fuel. Purpose. It consists in the development of a technology for obtaining multifunctional additives that improve the mechanical properties of gasoline and diesel fuels. Methodology.The subject of the research is to study the optimal conditions of the process of obtaining multifunctional modifiers based on metal and nitrogen-containing compounds, to obtain modifiers that increase the octane number of gasoline, and to develop the technology of obtaining metal-containing antidetonators. Originality. E-1, E-2 and E-3 organic esters containing oxygen as additives to increase the octane number of petroleum fuels, the effect on the octane number of the directly driven gasoline fraction compared to analogues is 0.4-1.82 units in the motor octanerating (MOR) method, 0 in the research octane rating (ROR) method. 7-2.5 units improved, and the effect of the gasoline fraction of the reformate sample on the octane number improved by 0.2-1.3 units in the ROR method, and by 0.1-1.1 units in the MOR method; Findings. According to the obtained preliminary results, the improvement of the octane number of the proposed modifiers with an effective effect on the octane number compared to their analogues allows the use of these modifiers as synergistic additives for increasing the octane number on the properties of petroleum fuels. [ABSTRACT FROM AUTHOR]

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology 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.)

Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design 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.)

In this study, almond shell waste (ASW) as filling material, pure (ER), and waste polystyrene modified bisphenol-A type epoxy resin (ER-PS) were used to obtain biobased composite materials. The modification of ASW was carried out with NaOH and linoleic acid (LnA). Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and Particle size distribution analyses were used in the characterization of ASW. Composites were prepared at filling ratios of 10-20-30-40-50% by mass using the casting technique. The morphology of the composites was characterized by SEM. The effects of epoxy matrix type and BK filling ratio on composites' mechanical, thermal, and water sorption properties were investigated. Tensile strength and modulus of elasticity (e-modulus) values of ERPS/ASW composites were lower, and tensile elongation values were higher than ER/ASW composites. The highest tensile strength values of 95-129 MPa were obtained for LnA modified ASW composites. The order of the tensile strength of the prepared ER matrix composites according to the filler type is: linoleic acid-modified ASW (LnA-ASW)>NaOH treated ASW (NaOH-ASW) > unmodified ASW. The most suitable ASW ratio was found as 30% by mass. e-modulus values of all modified ASW composites were higher than the epoxy matrix. According to the hardness test results, there was no significant difference between the composites. The water sorption of the composites increased depending on the ASW ratio and had a weakening effect on the mechanical properties. [ABSTRACT FROM AUTHOR]

In order to improve the resource generation level of forest and agricultural wastes, it was aimed to use fibrous organic isolation components by choosing pinecones whose seeds have been removed to be used in planting saplings and sunflower stems which need to be removed from the field in order to plant the next crop of sunflower after completing harvesting process. A lot of research is carried out to take advantage of the raw material potential of composite panel products. This study aims to produce an environmentally friendly composite low-density insulation board which can be utilized in structural activities by recycling pinecones and sunflower stems with sustainable vegetable fiber from forestry and agricultural wastes. The highest coefficient of thermal conductivity was found as 147,67 W/mK in samples with a thickness of 40 mm in pinecones with added sunflower stems; the thermal conductivity coefficient was determined as 2,94 W/m²K in samples with a thickness of 50 mm in pinecone. The highest adhesive strength was determined as 162,21 N/mm² in samples with a thickness of 40 mm in the pinecone with added sunflower stems. The modulus of elasticity was found as 292,05 MPa in samples with a thickness of 40 mm in the pinecone with added sunflower; vertical adhesive strength of the pinecone was determined as 81.89 N/mm² in samples with a thickness of 50 mm; screw withdrawal resistance was determined as 68,89 N/mm² in samples with a thickness of 50 mm in pinecones with added sunflower stems. [ABSTRACT FROM AUTHOR]

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology 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.)

Copyright of International Journal of Engineering Research & Development (IJERAD) is the property of International Journal of Engineering Research & Development 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.)

Copyright of Journal of Textiles & Engineers / Tekstil ve Mühendis is the property of Union of Chambers of Turkish Engineers & Architects, Chamber of Textile Engineers 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.)

Kompozit restorasyonların zaman için uygulayıcı hataları, hastanın kişisel alışkanlıkları ya da travma benzeri nedenlerle estetik ve fonksiyonel bütünlüklerinde bozulmalar görülebilmektedir. Bu gibi durumlarda direkt kompozit uygulamaları ile estetik ve fonksiyonel bütünlük yerine getirilebilmektedir. Estetik sebeplerle mevcut diş aralıklarının da yine direkt kompozit uygulamaları ile kapatılabilmektedir. Posterior bölgede ise estetikten ziyade hastalar fonksiyonel şikayetlerle kliniğimize başvurmaktadır. Büyük kavitasyonlu dişlerde indirekt uygulanan kompozitler ile daha uzun ömürlü tedaviler yapılabilmektedir. Yanlış diş fırçalama sonucu görülen fırça abrazyonun tedavisi direkt kompozit restorasyonlar ile mümkündür. İleri kemik kayıplı mobilitesi olan dişler uygulanan fiber ile güçlendirilmiş splint var olan dişlerin ağızda tutulmasını sağlamaktadır. Diş eksikliğiyle birlikte görülen yaygın ileri mobilite varlığında da eksik dişin yeri kompozit pontik ile doldurulup dişlere fiber ile güçlendirilmiş splint uygulanabilmektedir. Bu olgu sunumunda, kliniğimize estetik ve fonksiyonel şikayetler ile başvuran hastalarda, dokuların yapısal ve estetik devamlılığının sağlanması için gereken işlemler klinik vakalar üzerinden anlatılmıştır.

Ön bölgedeki şekil ve pozisyon bozukluklarının tedavisinde direkt kompozit rezin restorasyonlar uygulanabilmektedir. Bu olgu sunumunun amacı, direkt yöntemle kompozit rezin kullanılarak ön bölgedeki estetik sorunların tedavisi ile ilgili bir olgu sunumunu anlatmaktır. Kliniğimize estetik şikâyetlerle başvuran 32 yaşındaki erkek hastanın özgeçmişinde sistemik bir hastalığı olmadığı öğrenildi. Hastaya tedavi yöntemleri anlatıldı ve direkt kompozit veneerler ile dişlerin estetik olarak restore edilmesine karar verildi. Restorasyon tamamlandıktan sonra bitirme ve cila işlemleri yapıldı. 10 gün sonra yapılan klinik değerlendirmede; restorasyonların fiziksel özellikleri, marjinal bütünlüğü ve estetik özellikleri kontrol edildi. Kontrol seansında yapılan restorasyonların hastanın estetik beklentilerini karşıladığı belirlendi. Bu olgu sunumundan elde edilen değerlendirmelere göre kompozit veneerler ortodontik tedavi düşünülmeyen hastalarda estetik olarak alternatif bir tedavi seçeneği olabilir.

Endodontik tedavi görmüş ve fazla madde kayıplı dişlerin restorasyonu günümüzde hala zorluk olmaya devam etmektedir.Bu dişler için en yaygın kullanılan restorasyon çeşidi kanal içi postlar ve kron kaplamalardır. Ancak kanal içi postlar diş yapısını zayıflatmakta ve köklerin kırılma riskini artırmaktadır. Adeziv tekniklerdeki ilerlemeyle birlikte ayrı bir post ve kron olmadan,kor yapısı ve kron restorasyonunu bünyesinde birleştiren, böylece tek bir parçadan oluşan endokron restorasyonların kullanımı daha minimal invaziv olmaları sebebiyle yaygınlaşmaktadır. Endokronlar çoğunlukla pulpa odasından ve gerektiğinde de kök kanallarından destek alarak tutuculuk sağlayan, adeziv sistemlerle yeterli stabiliteyi elde eden monoblok restorasyonlardır. Bu olgu sunumunda kanal tedavili dişlerin indirekt kompozit rezin kullanılarak üretilen molar endokron restorasyonlar ile rehabilitasyonu üç farklı vakada ele alınmıştır. Bu olgu sunumunun amacı endokron restorasyonların aşamalarının anlatılması ve klinik takip sonuçlarının aktarılmasıdır.

Bu olgu sunumunda kama şeklindeki lateral dişlerde bulunan şekil bozukluğunun ve diestemaların direkt kompozit restorasyonlar ile konservatif olarak tedavisi amaçlanmıştır. Sistemik hastalığı bulunmayan 18 yaşındaki hasta estetik şikayetlerle kliğimize başvurdu. Hastaya uygulanabilecek tedavi yöntemleri açıklandıktan sonra dişlerin estetik olarak restorasyonunda direkt rezin kompozit kullanılmasına karar verildi. Kama lateraller silikon anahtar kullanılarak kompozit rezin (Essentia Starter Kit Syringe, GC, Japonya) ile restore edildi. Restorasyon tamamlandıktan sonra bitirme ve cilaişlemleri yapıldı. 18 ay sonra yapılan klinik değerlendirmede; restorasyonların fiziksel özellikleri, marjinal bütünlüğü ve estetik özellikleri kontrol edildi. Kontrol seansında yapılan restorasyonların hastanın estetik beklentilerini karşıladığı belirlendi. Bu olgu sunumunda, konik diş anomalilerinin kompozit rezin restorasyonlar ile tedavisi fiziksel özellikler, marjinal bütünlük ve estetik özellikler açısından klinik olarak yeterli sonuçlar vermiştir.

Dental arktaki iki daimi dişin kendi aralarında yerlerinin değişmesi sonucu gelişen alışılmadık ektopik erüpsiyon türü ‘’diş transpozisyonu’’ olarak tanımlanmaktadır. Çok sık görülmeyen bu diş anomalisi en fazla üst çene daimi kanin dişleri tutmaktadır. Üst çene ön bölge dişlerde şekil ve görünüm bozukluğuna sebep olan bu durum, estetik kaygılarla diş hekimlerine başvuran hastalarda tedavisi en zor diş anomalilerinden biri olarak görülmektedir. Literatürde diş transpozisyonları ile ilgili çeşitli tedavi seçeneklerinden bahsedilirken, dişlerin ortodontik tedavi ile transpozisyonda hizalanması ve sonrasında protetik veya restoratif işlemlerle yerinde bulundukları doğal dişlere benzetilmeleri tedavi seçeneklerinden birini oluşturmaktadır. Bu olgu sunumunda sağ üst çene santral ve lateral dişleri ortodontik tedavi ile transpozisyonda konumlanmış olan kadın hastanın kompozit veneer ve zirkonyum destekli porselen tam kron ile estetik rehabilitasyonundan bahsedilmektedir.

Bu olgu sunumu; yaygın çürüklü dişlerde direkt kompozit materyallerle yapılan estetik restorasyonların değerlendirilmesi amacıyla yapıldı. 26 yaşında nöropsikotik bozukluğa sahip erkek hasta, kliniğimize yaygın çürükleri nedeniyle başvurdu. Hastanın çürük risk durumunun kontrol altına alınması için yeme alışkanlıklarında değişiklikler ve ağız hijyeni motivasyonu yapıldı. Adeziv diş hekimliğinde son yıllardaki olumlu gelişmeler dişlerdeki çürük, kırık ve anatomik malformasyonlar gibi sebeplerle oluşan görünüş bozukluklarında direkt kompozitlerle başarılı restorasyonları mümkün kıldı. Bu vakada periodontal tedaviyi takiben rutin randevu seanslarıyla alt üst anterior dişler ve birinci premolar dişlere direkt kompozitlerle estetik restorasyonlar yapıldı. Direkt kompozit materyallerle yapılan estetik restorasyonların bu vakada hem estetik hem fonksiyonel olarak başarılı olduğu gözlendi.

Mine demineralizasyonu ve beyaz nokta lezyonları, ortodontik tedavi sırasında, yetersiz ağız hijyenine bağlı bakteri plağına uzun süre maruz kalınmasından dolayı ortaya çıkabilir. Bu olgu sunumunun amacı, ortodontik tedavi sonrası ön dişlerinde demineralizasyon alanları oluşmuş olan ve eski dolgularından memnun olmayan hastanın dişlerinin tedavisini aktarmaktır. Sağlıklı, 20 yaşında kadın hasta kliniğimize ön dişlerinin görünümünden şikayetçi olduğunu belirterek başvurdu. Klinik ve ragyografik muayeneler sonucunda; hastanın eski kompozit restorasyonlarının altında sekonder çürükler ve kole bölgelerinde yaygın beyaz nokta demineralizasyon alanlarının bulunduğu görüldü. Beyaz nokta lezyon bölgeleri için rezin infiltrasyon yöntemi uygulandı. Ancak demineralizasyon alanlarının derin oluşu ve hastanın hızlı estetik beklentileri göz önüne alınarak, estetik rezin kompozitler ile restorasyonlara karar verildi. Eski rezin restorasyonlar kaldırılarak estetik olarak yenilendi. 10 gün sonra kontrol seansında estetik ve fonksiyonel olarak hastanın beklentilerinin karşılandığı gözlemlendi.

İletken polimerler ve karışımları, diğer iletken malzemelerle kıyaslandığında, düşük yoğunluğa sahip, korozyon direnci yüksek işlenmesi kolay, düşük maliyetli ve kullanılan katkılarla birlikte metal ile kıyaslanabilir özellikte iletkenlik değerine sahip olmaktadır. Son yıllarda, metal – plastik değişimi üzerine birçok Ar-Ge çalışması yapılmıştır. Bu çalışmalarda, havacılık, uzay ve savunma sanayi, otomotiv ve otomotiv yan sanayinde kullanılmak üzere önemli polimer ve karışımları geliştirilmiştir. Metallerin en önemli özelliklerinden elektrik iletkenliği, elektromanyetik kalkanlama ve radyasyon emme, geliştirilen polimer ve karışımları ile sağlanabilmektedir. Polimer malzemelerin diğer avantajları ile, gelecekte bu sektörlerde daha fazla metalin yerini alacaktır. Bu çalışmada, polimerler ve karışımlarının elektriksel özellikleri ile ilgili özellikle son yıllarda yapılan ulusal ve uluslararası araştırma makaleleri derlenmiştir.

This study investigates the impacts of various materials depending on the quadcopter's determined flight altitude reference. On Solidworks, three different material groups are assigned to the body of the quadcopter design created for this study, these are polystyrene, carbon fiber reinforced epoxy composite, and 7075 aluminum alloy. Regardless of the body material, polystyrene material is used in the arms carrying the wings and engines. Mass calculations are made in the quadcopter according to the determined materials. In line with the calculations, a fuzzy logic-based PD controller is used for quadcopter altitude control. The input-output gains of the fuzzy logicbased PD are adjusted manually according to the reference height values and tests are carried out in the Matlab- Simulink environment. Four different values are determined for the test reference heights; these are 1 m, 1.5 m, 2.5 m, and 5 m, respectively. The test results show that the model with the polystyrene material in the body part is more successful than the other materials for the specified reference values. [ABSTRACT FROM AUTHOR]

With the development of nanotechnology, the use of nano materials with specific features in the construction industry, especially in the field of building materials, attracts attention by many researchers. According to the literature, carbon nanotubes (CNTs) are among the highly usable nanomaterials in the mixtures of cementitious materials. Although there are many studies on multi-walled carbon nanotube (MWCNT) added concretes, there are limited studies investigating the behavior of single-walled carbon nanotubes (SWCNTs) on concrete. In the present study, the mechanical and electrical properties of ultra-high performance concretes (UHPCs) produced by using SWCNT at the ratios of 0.0125, 0.020 and 0.025 % of cement weight were investigated. By adding 4.2 % steel fiber to the same mixtures, a total of 8 mixes with the reference were obtained. Conductivity and bending tests were carried out on 12X3X2 cm specimens. For electrical resistance measurement, the two-point uniaxial method, which is common in measuring cementitious materials, was used. According to the results, positive effects of SWCNT on mechanical properties have been observed. With the addition of SWCNT and increasing its ratio, the electrical resistance decreased, but it was found that high rates of SWCNT were required to increase the current rate. In addition, the effect of SWCNT was more pronounced in steel fiber added mixtures. [ABSTRACT FROM AUTHOR]

Copyright of Dokuz Eylul University Muhendislik Faculty of Engineering Journal of Science & Engineering / Dokuz Eylül Üniversitesi Mühendislik Fakültesi Fen ve Mühendislik Dergisi is the property of Dokuz Eylul Universitesi Muhendislik Fakultesi Fen ve Muhendislik Dergisi 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.)