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The most distinctive features of sound insulation structures are their flexibility and porosity. Therefore, the flexible epoxy matrix material was made cellular using a suitable foaming agent. In addition, hollow glass microspheres (HGMs) were added to the epoxy matrix. Thus, the sound wave refraction was increased by obtaining cavities in the cell walls. Structures with different densities and voids were created by changing the ratios of the filling material and foaming agents used in the sandwich. An aluminum (Al) honeycomb was used to protect the insulation materials\" structural integrity and ensure the homogeneous distribution of sound waves. The effect of density differences on sound insulation values was investigated. The mechanical properties of sandwich structures were determined using compression and three-point bending tests. The distribution of the filler in the matrix was visualized using SEM. TGA, DSC, thermal conductivity, dielectric, and flammability tests were also performed to determine their thermal, electrical, and flammability properties. During the formation of cells in the flexible epoxy, the HGMs were positioned in the cell wall by internal gas pressure. Low-density structures performed better at low frequencies, while high-density structures at high frequencies.

In this study, the synergistic effect created by adding Graphene (GE) nanoplatelets and carbon black (CB) fillers to the rubber matrix was used to determine the high stretchable sensor properties. GE and CB-filled rubber nanocomposite (HcN) strain sensors have been shown to detect and trace crack initiation and crack propagation of different sizes under cyclic loading. Tests were performed with four different crack sizes (0, 2.5, 5, and 10 mm) at five different strain levels (0%, 5%, 10%, 15%, and 20%) to determine the strain sensing performance of the specimens. The electrical response of HcNs under loading was measured with the four-point probe technique and recorded with a high-performance data acquisition system. The progression of external cracks created by scalpel on HcNs was examined by measuring electrical resistance changes caused by cyclic strain loading between 0% and 20%. The electrical response of 4 phr and 8 phr filled HcNs behaved qualitatively similar to each other, while 1 phr filled HcNs showed a significantly different response in terms of quality and quantity. In 4 phr GE-filled specimens, the resistance increase was changed steadily depending on the crack length, and unstable conditions occurred at 5 and 10 mm crack lengths at 1 and 8 phr GE filler ratios. The flexible and stretchable elastomer-based conductive strain sensing sensors, developed with the synergistic interaction of well-dispersed carbon-based fillers in the matrix, can detect and record damaged conditions caused by cyclic loading in many application areas.

Vinyl ester resins are widely used as matrix materials in particle and fiber reinforced composites. Nowadays, particles are also preferred in micron-sized microstructures to increase the mechanical properties of polymer matrix composites. In this work, vinyl ester matrix composites reinforced with aluminum oxide particles of 1-3 micron dimensions were produced. Mechanical properties such as tensile, 3 point bending, hardness, impact and wear properties of specimens prepared were investigated. Teflon mold was preferred to production of samples. In the reaction 50% active methyl ethyl ketone peroxide as initiator and 6% cobalt naphthalate as accelerator were used. Aluminum oxide was added to the vinyl ester resin at 0.5, 1, 1.5 and 2 wt% ratios. In order to disperse the particles in the mixture and prevent agglomeration, MEG (mono ethylene glycol) was added 5 times the amount of particles and the formulation was mixed in an ultrasonic mixer for 30 minutes. Tensile, % elongation, impact, hardness and wear properties were improved in 1.5% Al2O3 reinforced composite materials. A decrease in flexural strength was observed.

Vinyl ester resins are widely used as matrix materials in particle and fiber reinforced composites. Nowadays, particles are also preferred in micron-sized microstructures to increase the mechanical properties of polymer matrix composites. In this work, vinyl ester matrix composites reinforced with aluminum oxide particles of 1-3 micron dimensions were produced. Mechanical properties such as tensile, 3 point bending, hardness, impact and wear properties of specimens prepared were investigated. Teflon mold was preferred to production of samples. In the reaction 50% active methyl ethyl ketone peroxide as initiator and 6% cobalt naphthalate as accelerator were used. Aluminum oxide was added to the vinyl ester resin at 0.5, 1, 1.5 and 2 wt% ratios. In order to disperse the particles in the mixture and prevent agglomeration, MEG (mono ethylene glycol) was added 5 times the amount of particles and the formulation was mixed in an ultrasonic mixer for 30 minutes. Tensile, % elongation, impact, hardness and wear properties were improved in 1.5% Al2O3 reinforced composite materials. A decrease in flexural strength was observed., Vinil ester reçineleri, partikül ve fiber takviyeli kompozitlerde matris malzemeleri olarak yaygın olarak kullanılmaktadır. Günümüzde polimer matrisli kompozitlerin mekanik özelliklerini artırmak için mikron boyutlu mikro yapılarda da partiküller tercih edilmektedir. Bu çalışmada 1-3 mikron boyutlarında alüminyum oksit partikülleri ile güçlendirilmiş vinil ester matrisli kompozitler üretilmiştir. Hazırlanan numunelerin çekme, 3 noktada eğilme, sertlik, darbe ve aşınma özellikleri gibi mekanik özellikleri incelenmiştir. Numune üretiminde teflon kalıp tercih edilmiştir. Reaksiyonda başlatıcı olarak %50 aktif metil etil keton peroksit ve hızlandırıcı olarak %6 kobalt naftalat kullanılmıştır. Vinil ester reçinesine ağırlıkça %0.5, 1, 1.5 ve 2 oranlarında alüminyum oksit ilave edildi. Partiküllerin karışım içinde dağılması ve aglomerasyonun önlenmesi için partikül miktarının 5 katı MEG (mono etilen glikol) ilave edilmiş ve formülasyon ultrasonik mikserde 30 dakika karıştırılmıştır. %1,5 Al2O3 takviyeli kompozit malzemelerde çekme, % uzama, darbe, sertlik ve aşınma özellikleri iyileştirildi. Eğilme mukavemetinde bir azalma gözlendi.

Bu çalışmada ön ve arka kısımları kompozit yüzey plakalı sandviç bir levhanın balistik özellikleri sayısal analizler ile incelenmiştir. Tasarlanan balistik koruyucu malzeme ön ve arka plakaları karbon-aramid takviyeli epoksi kompozit malzemeden, orta çekirdek ise yüksek plastik şekil değiştirme özelliği ve hafif olması nedeniyle alüminyum plakadan oluşturulmuştur. Gerçekleştirilen bu tasarımda amaç; kompozit malzemenin enerji sönümleme mekanizmalarını kullanarak ön kompozit plakada mermi enerjisinin düşürülmesi, orta alüminyum plakanın plastik deformasyon ve sürtünme kabiliyetinden yararlanma ve arka kompozit plakada ise merminin nihai enerjisinin yayılarak tamamen yok edilmesi şeklindedir. Öncelikle mermi hareketi, hesaplamalı akışkanlar analizleri (CFD) ile incelenmiştir ve plaka ön yüzüne temas öncesi mermi hızı tespit edilmiştir. Mach sayısına göre değişen direnç katsayısı değerleri incelendiğinde CFD analizleri ile elde edilen sonuçların literatürdeki çalışmalar ile uyumlu olduğu görülmüştür. Bu çalışmada, kompozit plakalar ile balistik özellikleri artırılmış hibrit sandviç levhanın balistik performansları, NIJ 0108.01 standardı test prosedürüne göre LS DYNA yazılımı ile dinamik/eksplisit analizler gerçekleştirilerek nümerik olarak incelenmiştir. Mermi olarak 9x19 mm 8 gram ağırlığındaki Parabellum FMJ fişek seçilmiş ve farklı mermi hızlarında analizler gerçekleştirilmiştir. Kompozit plaka için malzeme kartı olarak MAT 22 malzeme kartı uygulanırken, hasar modeli olarak MAT59 kartı kullanılmıştır. Merminin herhangi bir deformasyona uğramayıp malzeme üzerinde meydana getirdiği hasarı gözlemlemek amacıyla mermi çekirdeği malzemesi için MAT 20 (MAT_RIGID) malzeme modeli kullanılmış ve çelik malzeme tanımı yapılmıştır. Yapılan simülasyonlar sonucunda tasarlanan kompozit plakalı sandviç panelin NIJ II-A ve NIJ II standardına göre mermi tarafından delinemediği ve balistik koruyucu malzeme olabileceği gösterilmiştir., In this study, the ballistic properties of a sandwich sheet with composite surface plate on the front and back were investigated by numerical analysis. The designed ballistic protective material front and back plates are made of carbon-aramid reinforced epoxy composite material, and the middle core is made of aluminum plate due to its high plastic deformation and lightweight. The aim of this design is to reduce the bullet energy in the front composite plate by using the energy absorption mechanisms of the composite material, to benefit from the plastic deformation and friction ability of the middle aluminum plate, and to completely destroy the final energy of the bullet in the back composite plate by spreading. First of all, the bullet motion was investigated by computational fluid analysis (CFD) and the velocity of the bullet before contact with the plate front was determined. When the resistance coefficient values varying according to the Mach number were examined, it was seen that the results obtained by CFD analysis were compatible with the studies in the literature. In this study, the ballistic performance of hybrid sandwich plate with enhanced ballistic properties with composite plates was investigated numerically by performing dynamic/explicit analyzes with LS DYNA software according to NIJ 0108.01 standard test procedure. Parabellum FMJ cartridge, 9x19 mm and 8 grams in weight, was chosen as the bullet, and analyzes were carried out at different bullet velocities. While MAT 22 material card was applied as material card for composite plate, MAT59 card was used as damage model. In order to observe the damage caused by the bullet without any deformation on the material, the MAT 20 (MAT_RIGID) material model was used for the bullet material and a steel material definition was made. As a result of the simulations, it has been shown that the designed composite plate sandwich panel cannot be perforated by the bullet according to the NIJ II-A and NIJ II standards and can be a ballistic protective material.

Composite materials are materialsobtained by combining materials with two or more different properties that areused by people for thousands of years to solve problems without being aware ofthem. Polymer based composite materials have recently been developed to improvethe properties of these materials, as they have many superior properties aswell as insufficient strength. Depending on technological developments, differenttypes of composites have been produced using different types of matrix andreinforcement.Thepurpose of this study, a new composite material using by polyesterfibers, acrylic fibers and polyamide fibers combining with araldite resinis produced and examined its mechanical properties. Thenew composites were produced by the method of hand lay-up . Themechanical properties such as tensile strength, impact strength, flexural strengthand interlaminar shear strength (ILSS) were performed. Based on the applications of themechanical tests of the composite samples, increasing of the fiber type andrate were seen an increase or decrease in mechanical properties.Keywords: Polyester Fiber, Acrylic Fiber, PolyamideFiber, Araldite Resin, Composite MaterialsPACS: 72.80.Tm 1. INTRODUCTIONThepolymers play very important role in our daily life. They can be combined withdifferent materials to achieve special properties according to end useapplications. Polymer based composites are being used more and more intensivelyin space, aviation, medicine, automotive, textile, construction, building andother developing technologies. Reinforcing fibers, which are generally used inpolymer composites, provide strength and other desirable properties to thecomposite material [1,2]. In parallel with these developments, working onfibers with better mechanical properties and higher heat-resistant,non-cracking, high impact strength and hard polymer matrices continue in theworld [3-7].Today, most of thesynthetic polymer fibers in use span applications such as clothing, carpets,ropes and reinforcement materials. Some of these fibers include polyamides suchas nylon, polyesters (as PET, PBT), PP, PE, vinyl polymers (as PVA, PVC), PUand acrylic fibers (e.g. PAN), [8,9].Polyamide refers to family of polymers called linear polyamides madefrom petroleum. The generic name polyamide fibre has the same meaning as nylonfibre, but nylon fibre is used principally in countries [10]. Polyamides generally are tough,strong, durable fibers useful in a wide range of textile applications. Thedistinguishing characteristics are high elasticity, tear and abrasion free, lowhumidity absorption capability, fast drying, no loss of solidity in a wetcondition, crease free, and rot and seawater proof. Application areas rangefrom underwear to outdoor sports clothing [11], from automotive to aerospace [12].PET is the world's most widely used fiber in a varietyof forms. PET is widely used in both fiber and filament forms as a strong,dimensionally stable fiber. Large quantities of PET fibers are also used forboth woven and nonwoven fabrics used for industrial and technical applications.Polyester fibers have many excellentproperties such as high strength, good stretchability, durability and easy carecharacteristics [13].Acrylic fiber is named asacrylonitrile containing at least 85% of its chemical structure according toISO (International Standards Organization) definition. Since acrylonitrile,which is predominantly homopolymerized with 100% acrylonitrile polymerization,is hard, brittle and difficult to paint, it has been converted into copolymersby the addition of a second monomer and is particularly suitably used intextiles. Acrylic fibers have a wide range of uses such as knitting, handknitting, carpet, blankets, velvet, socks [14]. Also acrylic fibre has beenextensively used in a number of industrial applications for example as a cursorfor carbon fiber, as substitute for asbestos in-fibre reinforced cement, and inhot gas and wet filtration [15]. 2. EXPERIMENTAL PROCEDURE2.1. Experimental Preparation and MechanicalAnalysisRENLAM LY113 aralditeresin (Huntsman) as the resin, Ren HY97 (Huntsman) as reaction initiator and Benzyldimethylamine(BDMA-Eastman) as accelerator were used in the composite matrix formulation.Acrylic fiber (Acrylic Tow, Type Extra / Gloss Dtex 2,2 - Lotno / Apre E-4316 /RA-01 Ktex 97) supplied from Aksa Acrylic Industry Company and polyester fiber andaramid fiber supplied from private sector were used as reinforcing materials.Composite materials using by polyester fibers, acrylic fibers andpolyamide fibers combining with araldite resin isproduced and examined its mechanical properties. Compositematerials were produced by the method of hand lay-up. The mechanicalproperties such as tensile strength, impact strength, 3-point bending strengthand interlaminar shear strength (ILSS) were investigated. In this study, two-piece semi-openmold made of stainless steel was produced to prepare standard tensile andimpact samples (Figure 1). Surfaces of the mold that are in contact with thecomposite are grind to prevent adhesion. Figure 1. Mold in which compositesamples are produced. 2.1.1. Tensile analysisThe tensile tests ofcomposite specimens were subjected to uniaxial tension with a constant tensilespeed of 5 mm/min and corresponding stress-strain values were recorded for maximumtensile strength determination with respect to fiber orientation. Tensileanalysis was applied on a Zwick Z010 universal tensile device. 2.1.2. Flexural analysisFlexural strength of thecomposite laminates were determined via 3-point bending tests done according toASTM D790-02 standart. Flexural analysis was applied with test speed of 5mm/min on a Zwick Z010 universal tensile device. Span to depth ratio was holdas 16:1. 2.1.3. Interlaminar shear strength (ILSS)analysisThe interlaminar shearstrength test samples (ILSS) according to ASTM D2344 standard was prepared andall of the tests made on a Zwick Z010 universal tensile device and applied witha test speed of 5 mm/min. 2.1.4. Impact analysisThe impact strength ofthe unnotched specimens was tested using a 5.4 J izod impact hammer on theZwick B5113.30 Izod Impact Device according to the ASTM D 256 standard. 2.2. Calculationof mold volume and resin formulationVolume of the mold: V = a x b x c= 11,5 x 19,5 x 0,4 =89,7 cm3 Resinformülation: 100 gr araldite resin (LY113) 32 gr hardener(HY97) 15drops BDMA (accelerator) 2.3. Densityof FibersTable 1. Densityof Fibers Polyester fiber Polyamide fiber Acrylic fiber Density (gr/cm3) 1,15 1,076 1,23 2.4. Calculation of the weights of the fibersin the mold2.4.1. Mass account for Acrylic Fibers%40Acrylic Fiber: %50Acrylic Fiber: %60Acrylic Fiber: m = d . v . 0,4 m = d . v .0,5 m = d . v .0,6m = 1,23 . 89,7 . 0,4 m = 1,23 . 89,7 .0,5 m = 1,23 . 89,7 . 0,6m = 44,132 gr. m =55,165 gr. m =66.199 gr 2.4.2. Mass account for Polyester Fiber %40Polyester Fiber: %50 Polyester Fiber: %60 Polyester Fiber: m = d . v . 0,4 m = d . v .0,5 m = d . v. 0,6m = 1,15 . 89,7 . 0,4 m = 1,15 . 89,7 . 0,5 m = 1,15 . 89,7 . 0,6m = 41,262 gr. m = 51,577gr. m = 61,893gr. 2.4.3. Mass account for PolyamideFiber %40Polyamide Fiber: %50 Polyamide Fiber: %60 Polyamide Fiber:m= d . v . 0,4 m = d . v . 0,5 m = d . v .0,6m= 1,076 . 89,7 . 0,4 m = 1,076. 89,7 . 0,5 m = 1,076. 89,7 . 0,6 m= 38,606 gr. m = 48,258 gr. m = 57,910 gr. Table 2. Weightsof Fibers In The Mold Materials Fiber Weights of Fibers In The Mold (gr) % 40 % 50 % 60 Polyester fiber 41,262 51,577 61,893 Polyamide fiber 38,606 48,258 57,910 Acrylic fiber 44,132 55,165 66,199 2.5.Preparation of the composite samplesThe prepared composite matrix resin consists of 100 grof araldite resin (Renlam LY113), 32% (32 gr) of Ren HY97 and 15 drops of BDMA.Composite samples were prepared by hand lay-up method. After addition of onecoat of resin into the open mold, the fibers cut according to the mold size toprovide the weights indicated in Table 2 were placed as shown in Figure 1. Theresin was applied to the intermediate layer and the top layer with the aid of abrush. The same procedures were applied to all fibers to produce compositeplatters containing 40%, 50% and 60% of individually polyester, acrylic andaramid fibers. Due to the difficulty of wetting the fibers of resin, it was notpossible to prepare samples with more than 60% by weight of fibers.The upper mold was closed and compressed withthe help of tacks to allow the resin to wet the fibers well and to remove airbubbles in the structure. After standing for 24 hours at room temperature, thecomposite layers removed from the mold were first of all edge trimmed, then thelayers were cut according to the standards specified in the relevant standardsand the burrs formed at the edges were sanded.3.RESULTS and DISCUSSIONIn this study, themechanical properties of the composite materials were investigated inconsideration of the weight and fiber volume fractions at different ratios. Foreach result given in the tables, five samples were produced for each test andaveraged.Table 3. and Figure 2.demonsrates tensile strength of composites molded at different rate. The fiberratio started at 40% and ended at 60%. In composite samples reinforcedpolyamide fiber and polyester fiber, the tensile strength increased withincreasing fiber amount. The maximum tensile strength value was reached in thecomposite sample of 50% polyamide fiber reinforced. After this, the tensilestrength was reduced. For polyester fiber reinforced composite samples, themaximum tensile strength value was observed in the sample with 60% polyesterfiber. In the acrylic fiber reinforced composite samples, the tensile strengthvalue decreased as the fiber ratio increased. The highest tensile strengthvalue was in the composite sample with 40% acrylic fiber. The tensiletest results show that the highest tensile strength in all composite sampleswas found in composite materials containing 60% polyester fibers. Table 3. Tensile test results ofcomposite materials Materials 40% Fmax (N) 50% Fmax (N) 60% Fmax (N) Polyamide fiber 140,82 144,4 111,3 Polyester fiber 95,27 172,63 177 Acrylic fiber 51,3 45,65 40,78 Figure 2. Tensile strength graphicsof composite materials Table 4. and Figure 3. show the flexural strength values obtained by the3-point bending test of all the composite samples. Composite samples withpolyamide and acrylic fiber reinforcement showed a decrease in flexuralstrength as the amount of fiber increased. Composite specimens with 40%polyamide fiber reinforcement and 40% acrylic fiber reinforcement showedmaximum flexural strength. At the 60% reinforcement ratio, the lowest flexuralstrength value was observed in both types of fibers. The maximum flexuralstrength value of polyester fiber reinforced composite specimens was 50%. 60%polyester fiber reinforcement showed lower flexural strength but higher than40%. Composite material reinforced 50% polyester fiber in all compositespecimens has the highest flexural strength value. Table 4. Three point bending testresults of composite materials Materials 40% σfm(Mpa) 50% σfm(Mpa) 60% σfm(Mpa) Polyamide fiber 86,69 85,49 82,94 Polyester fiber 92,00 140,01 131,13 Acrylic fiber 113,02 97,09 89,76 Figure 3. Flexuralstrengthgraphics of composite materials Table 5. and Figure 4. show the interlaminar shear strength (ILSS) ofthe composite specimens at the different rates. It has been observed that forevery 3 types of fibers used in this study, the ILSS strength is reduced byincreasing the amount of fiber. Polyamide, polyester and acrylic fiberreinforced composite samples with 40% ratio showed the highest ILSS strength,while 60% fiber reinforced composite samples had the lowest ILSS strengthvalue.The composite specimen reinforced 40% polyester fiber in all compositematerials showed the highest interlaminar shear strength value. Table 5. ILSS test results of composite materials Materials 40% σfm(Mpa) 50% σfm(Mpa) 60% σfm(Mpa) Polyamide fiber 199,51 125,03 110,66 Polyester fiber 205,24 148,87 111,29 Acrylic fiber 194,60 138,44 110,98 Figure 4. Interlaminar shear strength (ILSS) graphics of composite materials Table 6. and Figure 5. demonsrate impact strength obtained by the izodimpact test of all the composite samples. It has been observed that in all 3types of fibers used in this study, the increase in the amount of fiber alsoincreases the impact strength. Maximum impact strength was observed incomposite specimens reinforced 60% polyamide, polyester and acrylic fiber. In all composite specimens, the material with the highest impactresistance is composite material with 60% polyamide fiber reinforcement.Table6. Impact test results of composite materials Materials 40% (Kj/m²) 50% (Kj/m²) 60% (Kj/m²) Polyamide fiber 280,33 302,50 320,75 Polyester fiber 84,75 145,50 174,25 Acrylic fiber 44,50 108 158,75 Figure 5. Izodimpact strength graphics of composite materials 4. CONCLUSIONCompared tothe mechanical properties of composite specimens, composite specimensreinforced polyester fiber have the maximum tensile strength, flexural strengthand interlaminar shear strength. The polyamide fiber reinforced compositespecimen in all samples has the highest impact strength. In applications where tensile strength, flexural strength andinterlaminar shear strength are mentioned, polyester fiber reinforced compositematerial can be successfully used. It is clear that polyamide fiber reinforcedcomposites will be successful in many composite applications where tensile,flexural and ILSS strengths are not important at first but impact strength isimportant. Composite materials produced with acrylic fiber reinforcement at lowratios may also be preferred where tensile, flexural and interlaminar shearstrength is a concern.

Ates, Sabit Melih/0000-0001-7137-2096 WOS: 000441644300009 PubMed: 30074001 Objective: the aim of this study was to investigate the different surface treatments on the bond strength of self-adhesive resin cement to high-strength ceramic. Materials and Methods: Ninety aluminum oxide ceramic (Turkom-Ceramic Sdn. Bhd., Kuala Lumpur, Malaysia) specimens were produced and divided into nine groups to receive the following surface treatments: control group, no treatment (Group C), sandblasting (Group B), silica coating (Group S), erbium: yttrium-aluminum-garnet (Er: YAG) laser irradiation at 150 mJ 10 Hz (Group L1), Er: YAG laser irradiation at 300 mJ 10 Hz (Group L2), sandblasting + L1 (Group BL1), sandblasting + L2 (Group BL2), silica coating + L1 (Group SL1), and silica coating + L2 (Group SL2). After surface treatments, surface roughness (SR) values were measured and surface topography was evaluated. Resin cement was applied on the specimen surface, and shear bond strength (SBS) tests were performed. Data were statistically analyzed using one-way ANOVA and Tukey's multiple comparisons at a significance level of P < 0.05. Results: Group S, SL1, and SL2 showed significantly increased SR values compared to the control group (P < 0.05); therefore, no significant differences were found among the SR values of Groups B, BL1, BL2, L1, and L2 and the control group (P > 0.05). Group S showed the highest SBS values, whereas the control group showed the lowest SBS values. Conclusion: Silica coating is the most effective method for resin bonding of high strength ceramic, but Er: YAG laser application decreased the effectiveness.

ÖZETPOLİKARBONATIN YÜZEY ÖZELLİKLERİNİN IŞIKLA SERTLEŞEBİLEN SOL-JEL YÖNTEMİYLE İYİLEŞTİRİLMESİBu çalışmada herhangi bir bağlama ajanı ilavesine ihtiyaç duymadan organik-inorganik hibrid kaplamalarda faz ayrışımı problemini çözmek için yeni bir bifonksiyonel fotobaşlatıcı tasarımı amaçlanmıştır. Bu amaçla 1- hidroksisiklohekzil fenil-keton (Irgacure 184) ve 3-izosiyanatopropil trimetoksisilan (ICPTMS) arasındaki reaksiyonla yeni bir bifonksiyonel fotobaşlatıcı sentezlenmiştir. Sonrasında iyi dağılmış nano yapılı fazlar elde etmek için ağ formasyonunda ve fotobaşlatma prosesinde başlatıcının özelliklerini araştırmak amacıyla hibrid kaplamalar hazırlanmıştır. Hibrid kaplamalar sertlik, yapışma, aşınma, gerilme gibi çeşitli özellikleri karakterize edilmiştir. Kaplamaların termal ve morfolojik davranışları ayrıca değerlendirilmiştir. Bu yeni fotobaşlatıcı, organik ve inorganik fazlar arasında bağlama ajanı görevi de görmektedir. Yeni bifonksiyonel fotobaşlatıcı ve TEOS ile hazırlanan kaplamalar, polimerik filmlerin sertliğini dolayısıyla aşınma dayanımını arttırmıştır.ABSTRACTIMPROVEMENT OF SURFACE PROPERTIES OF POLYCARBONATE BY LIGHT CURABLE SOL-GEL METHODThe present paper focused on to design a new bifunctional initiator that was expected to solve the phase separation problem in organic–inorganic hybrid coatings without the need to add any coupling agent. To achieve this objective, first a new bifunctional photoinitiator was synthesized by the reaction between 1-hydroxy-cyclohexylphenyl-ketone (Irgacure-184) and 3-isocyanatopropyl trimethoxysilane (ICPTMS). Afterwards, the hybrid coatings were prepared to investigate the capability of the initiator in the photoinitiation process and in organic–inorganic network formation. The hybrid coatings were characterized by the analysis of various properties such as hardness, tape adhesion, abrasion, stress-strain. The thermal and morphological behavior of the coating were also evaluated. This new photoinitiator also acts as a coupling agent for inorganic and organic phases. The presence of the new bifunctional photoinitiator and TEOS, increased the hardness of the polymeric films and also improved the abrasion resistance.

ÖZET ENJEKSİYONLA KALIPLANMIŞ PLASTİK PARÇALARDA OLUŞAN YÖNLENME ve ARTIK GERİLMELERİN POLARİZE IŞIK MİKROSKOBU YARDIMIYLA İNCELENEREK KRİTİK NOKTALARIN BELİRLENMESİ Enjeksiyonla kalıplanmış bazı plastik ürünler, kullanım sırasında kırılarak kullanılamaz hale gelmektedir. Bunun sebebi, genellikle enjeksiyonla kalıplama sırasında oluşan artık gerilmeler ve gerilme yığılmalarıdır. Kalıplama sırasında oluşan artık gerilmeler ve gerilme yığılmalarının başlıca sebepleri imal edilen ürünlerde oluşan yönlenmeler ve soğuma sırasında meydana gelen büzülmelerdir. Yönlenme, malzeme içerisindeki yapısal ünitelerin (ki bizim konumuz itibariyle bu yapısal üniteler polimer zincirleri, polimer zincirlerinin segmentleri ve polimer içerisindeki kristalli bölgelerdir) bir dereceye kadar hizalanması anlamındadır. Bu çalışmanın amacı; yönlenme ve kalıntı gerilmelerin oluşum mekanizmalarının incelenmesi ve şeffaf plastik ürünlerdeki gerilmelerin gözlenmesi amacıyla basit bir polarize düzeneğin geliştirilmesidir. Temmuz 2001 Yalçın BOZTOPRAK vıı ABSTRACT DETERMINATION OF CRITICAL POINTS ON THE INJECTION MOLDED PARTS THROUGH INVESTIGATING ORIENTATIONS AND RESIDUAL STRESSES BY MEANS OF POLARIZED MICROSCOPY Some of the injection molded plastic products fail during service and become useless. The usual reasons for this are residual stresses and stress intensifications occuring during injection cycle. The origines of above problem are orientation and shrinkage of molded products. Orientation is the alignment of structural units of polymeric materials and very important in polymer processing. The aim of this study is to look into the mechanisms by which orientation and shrinkage occur and to develop a simple polarize equipment to observe the stresses present in the molded transparent plastic objects. Temmuz 2001 Yalçın BOZTOPRAK Vlll 134

Bu çalışmada, farklı oranlarda %3yttria stabilize zirkonyum oksit (ZrO2) ilavesinin atık koyun femur kemiklerinden elde edilmiş olan hidroksiapatite (KHA) etkisi incelenmiştir. Bu amaçla 4 farklı kompozit hazırlandı ve preslendikten sonra 1100-1300oC arasında 4 saat süre ile sinterlendi. Saf koyun hidroksiapatit için artan sinterleme sıcaklıkları ile yoğunluk, kısmi yoğunluk, sertlik ve kırılganlık indeksi artarken, en yüksek yatay (8.23±0.28 MPa) ve dikey basma (82.48±5.50 MPa) mukavemeti ve kırılma tokluğu (0.70±0.11 MPam1/2) 1200oC’ de elde edildi. Saf KHA’ in 1300oC’ de sinterlenmesi beta trikalsiyum fosfat (β-TCP), alfa trikalsiyum fosfat (α-TCP) ve kalsiyum oksit (CaO) fazlarına dekompoze olmasına neden olmuştur. Bu sıcaklık için saf KHA’ daki dekompoze olma oranı %4.1 olarak hesaplandı. KHA-ZrO2 kompozitlerinde dekompoze olma oranı, artan sinterleme sıcaklığı ve ZrO2 oranı ile %48.1’ e kadar artmıştır. KHA-ZrO2 kompozitlerinde iki farklı kalsiyum zirkonat (CaZr4O9 ve CaZrO3) fazı dedekte edilmiş olup, bu kompozitlerde dekompozisazyonun artışının CaZrO3 fazından kaynaklandığı kanaatine varılmıştır. 1200oC’ de sinterlenen KHA-2.5ZrO2 kompozitinin KHA-ZrO2 kompozitleri içerisinde en iyi özelliklere sahip olduğu belirlendi. Bu kompozitin kırılma tokluğu 1.25±0.08 MPam1/2, dikey ve yatay basma mukavemeti değerleri ise 122.0±2.12 MPa ve 11.21±0.42 MPa’ dır. Ancak; KHA-ZrO2 kompozitinin yetersiz kırılma tokluğu özelliği nedeniyle insan vücudunda yüke dayanım gerektirmeyen uygulamalarda kullanılması önerilmektedir.

Mevcut birçok hekzaborür arasında lantan hekzaborür (LaB6), 2.4 eV ila 2.9 eV arasındaki düşük iş fonksiyonu, düşük direnci, yüksek erime sıcaklığı, yüksek kimyasal stabilitesi ve düşük buharlaşma sıcaklığı gibi özellikleri sayesinde endüstriyel uygulamalar için umut vaad etmektedir. LaB6 ve CeB6 sahip oldukları düşük iş fonksiyonu, yüksek akım ve gerilim kapasitesi ve düşük buhar basıncı özellikleri sayesinde geçirimli elektron mikroskobu (TEM), taramalı elektron mikroskobu (SEM) gibi elektron mikroskoplarında yüksek parlaklık ve uzun ömür sunan termiyonik elekton kaynağı olarak tercih edilmektedir. LaB6 elektrik alan yayıcıları aynı zaman da düz panel ekranlar, RF ve mikrodalga (MW) elektron tüplerinde, vakum elektroniği için mikron boyutlu elektron yayıcılarda da kullanılmaktadır. Bu tez çalışmasında, elektron mikroskoplarında elektron kaynağı olarak kullanılan LaB6 katotların magnetron sıçratma (MS) sistemi kullanılarak yüksek kaliteli ve düşük maliyetle ince film filament olarak üretilmesi hedeflenmektedir.Bu amaçla, öncelikle LaB6 kaplı filamentlerin üretilebilmesi için yapılacak olan kaplama deneylerinin tasarımı yapılarak Marmara Üniversitesin’de bulunan magnetron sıçratma sistemleri kullanılacaktır. Hedef malzeme olarak LaB6 kullanılacak olup alttaş olarak kullanılacak tungsten, molibden, tantal tellerin magnetron sıçratma sistemi kullanılarak kaplanması ve özelliklerinin analiz edilip geliştirilmesi üzerine çalışmalar yapılacaktır. Alttaşlar öncelikle ara katman kullanılmadan belirlenen deney parametreleri ile doğrudan olarak hedef malzemeyle kaplanacak olup alttaşlardaki yapışmanın yeterli olmadığı durumda ise alttaş üzerlerine ince karbon (C) veya ara katmanı eklenerek çalışmalar yapılacaktır. Elde edilen filmlerin kırılgan olması, kompozisyonlarının düzgün olmaması ve ölçülen değerlerin hedeflenen referans değerlerinden farklı olması halinde ise hedef kompozisyonu, magnetron sıçratma sistem parametrelerinin değiştirilerek istenilen kompozisyonda kaliteli filamentlerin üretilmesi amacıyla çalışmalar yapılacaktır. Çalışmalar sonucunda elde edilen LaB6 filamentlerin Taramalı Elektron Mikroskobu (SEM), X-Işını Kırınımı (XRD), X-Işını Fotoelektron Spektroskopisi (XPS) analizleri ve bant testi ölçümleri yapılacak olup çalışma parametreleri ve elektron emisyon değerleri belirlenerek karakterizasyon işlemleri tamamlanacaktır. Among many hexaborides, lanthanum hexaboride (LaB6), due to its low working function, low resistance, high melting temperature, high chemical stability, and the low evaporation temperature is promising for industrial applications. Thanks to their low operating function, high current and voltage capacity, and low vapor pressure properties, LaB6 and CeB6 are preferred as a thermionic electrode source that offers high brightness and long life in electron microscopes. Also, possible applications of LaB6 field emitters include flat-panel displays and micron-sized electron emitters for vacuum electronics. In this thesis, high quality and cost-effective production of LaB6 filaments, which are used as an electron source in electron microscopes are aimed to produce by magnetron sputtering (MS). For this purpose, the design of coating experiments will be done primarily for the production of LaB6 filaments which will be produced by using the magnetron sputtering system (MS) in Marmara University. Tungsten, molybdenum, and tantalum wires will be coated magnetron sputtering system by using LaB6 commercial target. Firstly, the substrates will be coated with target materials without using intermediate layers and if there is not enough adhesion on substrates, thin carbon (C) interlayer will be formed. If the films obtained are fragile, their composition is not smooth and the obtained values are different from the reference values, studies will be performed to produce high-quality films in the desired composition by changing the target composition, magnetron sputtering system parameters. LaB6 films obtained as a result of studies will be characterized by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) analysis, and tape-test measurements. In addition, by determining the working parameters and work function, characterization procedures will be completed.

Tarihin ilk dönemlerinden bugüne insanlık, kendini ve yaşadığı yeri savunmayı hedefleyen bulgular aramış ve bu doğrultuda sürekli yeni şeyleri geliştirmeyi hedeflemiştir. Zırh malzemelerinin, ateşleyici silahların ve hatta kompozit malzemelerin temelleri dahi bu doğrultuda atılmış ve günümüze dek ilerlemiştir. Üretim endüstrisinde ise metal olmayan kompozit malzemeler; çelik ve diğer metallerinyerine alternatif olarak kullanılmaya başlanmıştır. Bu tez ile ülkemizde çok önemli bir yeri olan ve kullanımı gittikçe artan kompozit malzemeler hakkında çalışma yürütülmüştür. Gelişmekte olan ve gelecekte çok daha önem kazanması öngörülen bu malzeme sınıfı hakkında geniş bir araştırma yapılarak önemli bilgilerin derlenmesi ve bir kaynak oluşturulması, ayrıca bu malzemeler hakkında diğer bilim insanlarının da faydalanacağı bir tez çalışması hedeflenmiştir.Günümüzde teknolojinin gelişmesi ile ortaya çıkan yüksek mukavemet ve elastikiyet özelliklerine sahip hafif kumaşların polimerlerle kombinasyonları, balistik panel ve zırh üretiminin temelini oluşturmaktadır. Ayrıca daha geniş bir malzeme seçimi ve üretim kolaylığı, onları mühendislik uygulamaları için ideal kılmaktadır. Askeri alanlar başta olmak üzere balistik alanında yapılan yatırım, akademik ve askeri çalışmalar bu konunun önemini ortaya koymaktadır. Bu tez çalışmasında karbon ve aramid fiberler dokuma tezgahında üç katmanlı olarak dokunmuştur. Dokuma kumaşlar 3 katmanlı olarak %100 karbon ve %100 aramidelyaflar şeklinde 4 farklı kombinasyonda tasarlanmıştır. Matris malzemesi olarak epoksi reçinesi seçilmiş ve 4 farklı kompozit malzeme tasarlanmıştır. Gerçekleştirilen dokuma tasarımlarına ait malzeme modelleri MSC/Digimat yazılımı kullanılarak hesaplanmış ve gerekli malzeme karakterizasyonları belirlenmiştir. Elde edilen malzeme verileri ile tasarlanan kompozit yapılar Sonlu Elemanlar Simülasyonları gerçekleştirerek incelenmiştir. Sonuçlar, tasarlanan kompozit yapılar için karşılaştırmalı olarak değerlendirilmiştir. From the first periods of history to the present, humanity has searched for findings aiming to defend itself and the place where you live, and in this direction, it has aimed to develop new things constantly. Armor materials, firearms, and perhaps even the foundations of composite materials were laid in this direction and progressed until today.Non-metal composite materials in the manufacturing industry; it has started to be used as an alternative to steel and other metals. With this thesis, a study has been carried out on composite materials, which have a very important place in our country and are increasingly used. It is aimed to compile important information and create a resource by conducting extensive research on this developing material class, which is expected to gain much more importance in the future and also to publish a study about these materials that other scientists will benefit from.Polymer composite materials have started to be used as alternatives in the manufacturing industry instead of steel and other metals. Polymers and polymer matrix composites are increasingly used due to their high strength and low density. Additionally, a wider selection of materials and ease of production make them ideal for engineering applications. Nowadays, polymer matrix composite armors are widely used as an armor material and the use of composite armor for ballistic purposes is becoming more and more widespread. The combination of lightweight fabrics with high resistance and elasticity, which has emerged with the development of technology nowadays, is the basis of ballistic panels and armor production. Additionally, a more comprehensive selection of materials and ease of production make them ideal for engineering applications. Investments made in the field of ballistics, especially in military fields, and academic and military studies reveal the importance of this claim.ixThe 3-layer fiber fabrics used in this study were wovens. Woven fabrics are woven in 4ways: 100% carbon fiber and 100% aramid fiber fabrics. Epoxy resin was chosen as the matrix material, and four different composite materials were designed. The material models of the realized weaving designs were calculated using MSC/Digimat software,and the necessary material characterizations were determined. Composite structures designed with the obtained material data were examined by performing Finite Element Simulations. The results were evaluated comparatively for the designed composite structures.

Son yıllarda inorganik partiküllerle takviyelendirilmiş polimer matrisli kompozitler yaygın bir şekildekullanılmaktadır. Yapılan çalışmaların birçoğu, polimer malzemelere inorganik yapıların ilavesiyle elde edilenhibrid malzemeler üzerine yoğunlaşmıştır. Bu çalışmada, bor nitrür partikül takviyeli vinil ester kompozitmalzemeler üretilmiştir. Matris malzemesi olarak vinil ester reçinesi kullanılmıştır. Takviye malzemesi olarakise ortalama 70 nm boyutlarında olan hegzagonal bor nitrür partikülleri kullanılmıştır. Farklı oranlarda üretilenbor nitrür takviyeli vinil ester kompozit numunelerin çekme dayanımı, eğilme dayanımı, darbe dayanımı, aşınmadayanımı ve sertlik özellikleri incelenmiştir. Test numunelerini hazırlamak için kalıp malzemesi olarak silikontercih edilmiştir. Reaksiyon başlatıcı olarak %50 aktif metil etil keton peroksit, hızlandırıcı olarak ise % 6’lıkkobalt naftalat kullanılmıştır. Partiküllerin homojen dağılımını sağlamak ve topaklanmayı engellemek içinpartikül miktarının 5 katı oranında MEG (mono etilen glikol) ilavesiyle elde edilen karışım, ultrasonik karıştırıcıiçerisinde 30 dakika karıştırılmıştır. Vinil ester reçine içerisine bor nitrür ilavesi işlemine ağırlıkça % 0,5oranından başlanmış ve % 2’ye kadar devam edilmiştir. Elde edilen kompozit malzemenin darbe ve sertlikdeğerlerinde artış görülmüştür. Çekme, % uzama ve eğilme özelliklerinde azalma gözlemlenmiştir. Aşınmamiktarında ise azalma, dolayısıyla aşınma dayanımında artış olduğu görülmüştür. In recent years inorganic particles reinforced polymer matrix composites have been widely used._x000D_ Many of the studies has focused on hybrid materials obtained by the addition of inorganic structures to polymer_x000D_ materials. In this work, boron nitride particle reinforced vinyl ester composite materials were produced. The_x000D_ vinyl ester resin as matrix material was used. Boron nitride particles having an average size of 70 nm were used_x000D_ as reinforcement material. Tensile strength, flexural strength, impact strength, abrasion strength and hardness of_x000D_ boron nitride reinforced vinyl ester composite specimens produced at different ratios were investigated. Silicone_x000D_ was preferred as a mold material to prepare the test specimens. 50% active methyl ethyl ketone peroxide was_x000D_ used as the reaction initiator and 6% cobalt naphthalate was used as the accelerator. The mixture obtained by_x000D_ adding MEG (mono ethylene glycol) at 5 times the amount of particles to ensure homogeneous distribution of_x000D_ the particles and to prevent agglomeration, was stirred in the ultrasonic mixer for 30 minutes. The addition of_x000D_ boron nitride into the vinyl ester resin was started with 0.5% by weight and continued until 2% by weight._x000D_ Impact and hardness values increased. A decrease in tensile,% elongation and bending properties was observed._x000D_ There was a decrease in the amount of wear and therefore an increase in wear resistance.

Özellikle son yıllarda mühendislik alanında yaşanan gelişmeler sayesinde yüksek dayanım/yoğunluk ve elastik modülü/yoğunluk oranı elde edilmesiyle daha üstün nitelikli kompozit malzeme üretimi ve performans özellikleri üzerine yapılan araştırma ve geliştirme faaliyetleri artarak devam etmektedir. Son yıllarda gelişen lif teknolojisi ile birlikte kırılgan malzemenin zayıf olan yönlerinin iyileştirilmesi, kırılganlığın giderilmesi, mukavemetinin arttırılması için karbon elyaf gibi üstün özelliklere sahip teknik liflerin kompozit malzemelerde çeşitli formlarda takviye malzemesi olarak kullanımı yaygınlaşmıştırSon zamanlarda bazalt lifleri, cam elyafların yerine iyi bir doğal ikame olarak kullanılmaktadır. Çünkü bazalt, kayalardan elde edilir ve bazalt liflerinin insan sağlığına zararsız ve biyoinert olduğu deneysel olarak kanıtlanmıştır. Bazalt lifleri, bazalt kayaçlarının yüksek sıcaklıklarda ergitilmesiyle kısa ve sürekli filamanlar olarak üretilmektedir. Bazalt liflerin proses teknolojisinin iyileştirilmesiyle yeni nesil bazalt lifleri ses yalıtımı özellikleri, mükemmel ısı direnci (camdan daha iyi), kimyasallara karşı dayanım ve düşük su emilimi gibi olumlu performans özelliklerini göstermektedir. Bu nedenle daha yüksek ısı direnci gerektiren uygulamalarda kullanılmaları önerilir. Bir başka önemli özellik ise daha düşük maliyetle birlikte cam elyaf ile karşılaştırılabilir bir yüksek mekanik performans göstermesidir.Bu çalışmada karbon prepreg ve cam prepreg ile birlikte bazalt elyaf kullanılarak sıcak pres (hot press) yöntemiyle uygun sıcaklık ve basınçta hibrit kompozit malzemeler elde edilecek ve elde edilen kompozit malzemelerin mekanik özellikleri incelenecektir.--------------------Especially in recent years, thanks to the developments in the field of engineering, high strength / density and elastic modulus / density ratio has been achieved and the research and development activities on the production of superior quality composite materials and performance properties are increasingly continuing. In recent years, with the developing fiber technology, the use of technical fibers with superior properties such as carbon fiber to improve the weaknesses of the brittle material, to improve brittleness, and to increase the strength have become widespread in composite materials in various forms.Recently, basalt fibers have been used as a good natural substitute for glass fibers. Because basalt is obtained from rocks and it has been experimentally proven that basalt fibers are harmless to human health and bioinert . Basalt fibers are produced as short and continuous filaments by melting basalt rocks at high temperatures . With the improvement of process technology of basalt fibers, new generation basalt fibers have sound insulation properties, excellent heat resistance (better than glass), resistance to chemicals and low water absorption. properties. Therefore, it is recommended to use in applications requiring higher heat resistance. Another important feature is the high mechanical performance comparable to that of glass fiber with lower cost.In this study, hybrid composite materials will be obtained by using hot press method at appropriate temperature and pressure by using basalt fiber together with carbon prepreg and glass prepreg and mechanical properties of the obtained composite materials will be examined.