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Boron nitride-MWCNT/epoxy hybrid nanocomposites: Preparation and mechanical properties
(ELSEVIER SCIENCE BV, 2014) Ulus, Hasam; Ustun, Tugay; Eskizeybek, Volkan; Sahin, Omer Sinan; Avci, Ahmet; Ekrem, Mursel
In this study, production and mechanical properties of hybrid nanocomposites have been investigated. Hybrid nanocomposites are consisting of boron nitride nanoplatelets (BN) and multiwall carbon nanotubes (MWCNT) embedded in epoxy resin. The BN and MWCNT were mixed to epoxy resin in different weight fractions and mixtures were utilized for tensile test specimen production. The synthesized BN and produced hybrid nanocomposites were characterized by SEM, TEM, XRD, FT-IR and TGA analyses. The elasticity modulus and tensile strength values were obtained via tensile tests. The fracture morphologies were investigated after tensile test by means of scanning electron microscopy. (C) 2013 Elsevier B.V. All rights reserved.
CNT-PAN hybrid nanofibrous mat interleaved carbon/epoxy laminates with improved Mode I interlaminar fracture toughness
(ELSEVIER SCI LTD, 2018) Eskizeybek, Volkan; Yar, Adem; Avci, Ahmet
Interleaving laminated composites with electrospun nanofibrous mats comes out as a promising micro scale strategy to strengthen interlaminar regions of laminated composites. The aim of this study is to evaluate the synergetic contribution of nano- and micro-scale mechanisms on interlaminar delamination. For this, carbon nanotubes (CNTs) reinforced polyacrylonitrile (PAN) electrospun hybrid mats were successfully fabricated and utilized as interleaves within the interlaminar region of carbon/epoxy laminated composites. The Mode I interlaminar fracture toughness values were enhanced up to 77% by introducing CNTPAN nanofibrous interleaves. Specifically, the nano-scale toughening mechanisms such as CNTs bridging, CNTs pull-out, and sword-sheath increased the Mode I fracture toughness by 45% with respect to neat PAN nanofibrous interleaves. The related micro- and nano-scale toughening mechanisms were evaluated based on the fracture surface analysis. Atomic force microscopy was also utilized to quantify the magnitude of surface roughness changes on the interlaminar region with respect to multi scale interleaving reinforcement and correlate surface roughness changes due to crack deflection to increased fracture toughness. (C) 2018 Elsevier Ltd. All rights reserved.
Electrospun TiO2/ZnO/PAN hybrid nanofiber membranes with efficient photocatalytic activity
(ROYAL SOC CHEMISTRY, 2017) Yar, Adem; Haspulat, Bircan; Ustun, Tugay; Eskizeybek, Volkan; Avci, Ahmet; Kamis, Handan; Achour, Slimane
Electrospun polyacrylonitrile (PAN) nanofibers were decorated with TiO2, ZnO and TiO2/ZnO nanoparticles for the first time to prepare flexible multifunctional nanofibrous membranes. First, the arc-discharge process was utilized to prepare TiO2, ZnO and TiO2/ZnO nanoparticles and then the hybrid electrospun nanofibers were spun from PAN/nanoparticle colloids. X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to characterize the resulting nanoparticles and nanofiber loaded nanoparticles. The microscopic investigations revealed that the specifically TiO2 nanoparticles tend to agglomerate within the PAN nanofiber resulting increased surface roughness; however, ZnO nanorods with 1D morphology are aligned as parallel to the fiber axis. Photocatalytic activity of the hybrid nanofibers was performed by pursuing the degradation of malachite green (MG) dye under UV light irradiation. The fabricated TiO2/ZnO/PAN hybrid nanofibers showed excellent photocatalytic efficiency with at least two times higher reaction rates compared to the bare PAN nanofibers. The results suggest that the photocatalytically active TiO2/ZnO/PAN hybrid nanofibers can be considered as filtering materials for a variety of applications in the fields of wastewater systems without the need of post processing stages for separating catalysts from the liquid medium.
Enhanced fatigue performances of hybrid nanoreinforced filament wound carbon/epoxy composite pipes
(ELSEVIER SCI LTD, 2016) Ustun, Tugay; Eskizeybek, Volkan; Avci, Ahmet
In filament wound composite pipes matrix cracking, as an initial damage mechanism during fatigue loading, can initiate a damage sequence that can result in catastrophic failure of the pipes. Matrix modification using nanostructured fillers is an emerging approach to develop new fatigue-resistant composite materials. The aim of this study to investigate the fatigue performance experimentally, and observe macroscopic and microscopic damage mechanisms of carbon fiber/epoxy filament wound composite pipes toughened by carbon nanotubes ( CNTs) and boron nitride nanoplates (BNNPs). The effectiveness of nanofillers with different morphologies on fatigue damage development and their micro/nano reinforcing mechanisms were discussed. The fatigue tests with positive cycling pressure loading were performed at three different load levels as 50%, 60%, and 70% of the static burst strength of each samples. S-N curves were obtained according to fatigue test and lifetime of the fabricated hybrid composite pipes were evaluated. The addition of nanoscale reinforcements increase fatigue performance of the composite pipes for all cases. To analyze damage initiation and final damage, microscopic analyses of the fracture surfaces were utilized. The fractographic investigations revealed that the morphologies of nanofillers play a key role on improving mechanical performance by generating different nano- and micro-scale toughening mechanisms. (C) 2016 Elsevier Ltd. All rights reserved.
Evaluating the effectiveness of nanofillers in filament wound carbon/epoxy multiscale composite pipes
(ELSEVIER SCI LTD, 2016) Üstün, Tugay; Ulus, Hasan; Karabulut, Salim Egemen; Eskizeybek, Volkan; Şahin, Ömer Sinan; Avcı, Ahmet; Demir, Okan
The performance of filament wound (FW) composite pipes is considered to be fundamentally governed by fiber properties and winding angles; however, matrix dominated properties such as axial and hoop strengths are also responsible in design of FW composite pipes. This paper presents the experimental results of a project aiming to assess the benefits of addition of carbon nanotubes (CNTs) and/or boron nitride nanoplates (BNNPs) as nanofillers within epoxy matrix of FW carbon fiber composite pipes. The nanofillers enhance the burst and hoop strengths up to 17.0% and 31.7%, respectively, over the control samples. Failure analysis revealed that the morphologies of nanofillers play an important role on the matrix toughening and strengthening the fiber matrix interface. Highest mechanical performance of the multiscale composite pipes was obtained with the addition of CNTs and BNNPs within the epoxy matrix concurrently related with the synergetic effect of the two different nanofillers. (C) 2016 Elsevier Ltd. All rights reserved.
Fatigue Behavior and Damage Assessment of Stainless Steel/Aluminum Composites
(ASME-AMER SOC MECHANICAL ENG, 2011) Eskizeybek, Volkan; Avci, Ahmet; Akdemir, Ahmet; Sahin, Omer Sinan
Fatigue crack growth and related damage mechanisms were investigated experimentally in a stainless steel/aluminum laminated composite with middle through thickness crack, and two different fracture mechanics approaches applied to the composite to reveal their differences under fatigue loading. The laminated composite material, which has a unidirectional continuous AISI 304 stainless steel as fibers and Al 1060 as matrix, was produced by using diffusion bonding. Fatigue tests were conducted in accordance with ASTM E 647. The relationships between fatigue crack growth rate (da/dN), stress intensity factor (Delta K), and strain energy release rate (Delta G) were determined; and damage behavior was discussed. Both linear elastic fracture mechanics (LEFM) and compliance method were used, and the results were compared with each other. It is found that as the crack propagates, the LEFM overestimates the Delta G values. Interlaminar and fiber/matrix interface damage were evaluated by fractographic examination. [DOI: 10.1115/1.4003490]
Influence of flake size on the morphology of wet spun graphene oxide fibers
(Selçuk Üniversitesi Mühendislik Fakültesi, 2018) Eskizeybek, Volkan
For using graphene in practical applications, it is crucial to transform the unique and individual properties of graphene flakes into ordered macroscopic materials. The physical and chemical properties of macroscale graphene structures are closely related to the size of graphene flakes as building blocks. However, the chemical methods adopted to synthesize graphene oxide (GO) flakes offer no tight control on the dimensionality of the ensuring flakes sizes. The goal of this study is to investigate morphological evaluation of graphene based fibers fabricated using building blocks with different average size.. A facile and effective centrifugation method was carried out for size sorting of graphene oxide flakes. Macroscopic graphene oxide fibers were continuously spun from graphene oxide/water suspensions followed by chemical and thermal reductions to obtain reduced graphene oxide fibers. All wet spinning parameters such as suspension concentration, injection rate and nozzle diameter were fixed to investigate the effect of average building block size on the structural morphology of the fibers. Microscopic investigations revealed that the flake size have an enormous impact on the morphology of graphene oxide fibers. The increased average flake size results in the fibers with rectangular-like cross-section and increased amount of voids within the graphene oxide fiber.
Low-velocity impact behavior of carbon fiber/epoxy multiscale hybrid nanocomposites reinforced with multiwalled carbon nanotubes and boron nitride nanoplates
(SAGE PUBLICATIONS LTD, 2016) Ulus, Hasan; Ustun, Tugay; Sahin, Omer Sinan; Karabulut, Salim Egemen; Eskizeybek, Volkan; Avci, Ahmet
In this article, the mechanical properties and dynamic response of hybrid filler-modified epoxy/carbon fiber multiscale composites were investigated. The hybrid fillers composed of multiwalled carbon nanotubes and boron nitride nanoplates were dispersed in epoxy resin and used as matrix material. The multiscale hybrid laminated composites were stacked symmetrically consisting of 10 plies of woven carbon fibers and fabricated by vacuum infusion technique. The mechanical properties of the hybrid composites were investigated by tensile tests. Impact response and energy absorption capacity were investigated by using weight drop test method and the tests were performed according to ASTM-D-7136 standard with impact energies of 5, 10, and 15J. The impact force and displacement versus interaction time were measured. The impulsive force, energy absorption capability, and damage formation were also investigated. It is observed that when the resin is modified by nanoparticles, both strength and the % strain at fracture increase considerably. However, it is shown in the subject manuscript that the enhancement of mechanical has not fully transferred to dynamic response and energy absorption capacities of nanocomposites.
The Mode I interlaminar fracture toughness of chemically carbon nanotube grafted glass fabric/epoxy multi-scale composite structures
(ELSEVIER SCI LTD, 2014) Eskizeybek, Volkan; Avci, Ahmet; Gulce, Ahmet
A novel and simple chemical route was successfully applied to graft carbon nanotubes (CNTs) onto silanized plain weave glass fabric (PWGF) mats, as confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy. The CNTs grafted PWGF mats were used to reinforce epoxy matrix for multi-scale composite production due to their potential for increasing interlaminar fracture toughness by bridging the ply interfaces. Grafting CNTs onto PWGFs improved both initial and steady-state toughness more than double as measured by Mode I interlaminar fracture testing. Failed specimens were visualized to determine the failure modes using fractography. The key findings indicated that the covalent interactions created between CNTs and fibers lead fibers bridging the interface region like "barbed wires", which are mainly responsible for increased fracture toughness as a result of improved interfacial adhesion. (C) 2014 Elsevier Ltd. All rights reserved.
Modification of cellulose acetate nanofibers with PVP/Ag addition
(ELSEVIER SCI LTD, 2014) Kendouli, S.; Khalfallah, O.; Sobti, Nadjah; Bensouissi, A.; Avcı, Ahmet; Eskizeybek, Volkan; Achour, Slimane
in this work cellulose acetate (CA) nanostructures were synthesized using electrospinning process. Silver nanoparticles (Ag NPs) were synthesized using silver nitrate as the starting precursor, ethanol as solvent and polyvinyl pyrolydone (PVP) as capping agent. The Ag NPs were added to the cellulose acetate (CA) nanostructures before and after CA electrospinning. The obtained CA and Ag-CA composite were characterized by various techniques such as, Fourier Transform Infrared (FTIR) spectroscopy, Raman Spectroscopy, Scanning electron microscopy (SEM) and Differential Scanning Calorimetry (DSC). It was found that Ag NPs can be effectively coated on or embedded into the electrospun CA and the PVP can lead to noticeable change in morphology and structure. (C) 2014 Elsevier Ltd. All rights reserved.
Optical Constants of Thin Film Prepared by the Cd(OH)(2) Nanowires Synthesized Using the Arc Discharge Method
(AMER SCIENTIFIC PUBLISHERS, 2014) Akın, Ümmühan; Şafak, H.; Eskizeybek, Volkan; Avcı, Ahmet; Yüksel, Ömer Faruk
The optical constants of thin film prepared by cadmium hydroxide nanoparticles spray coated on the glass substrate held about at 100 degrees C temperature have been investigated using the optical transmission and reflection spectra. The transmission spectrum exhibits that the film has a high transparency (similar to 80%) at the infrared region. From standard optical analysis, direct band gap energy of Cd(OH)(2) was found as 3.13 eV, and also, it was seen that the calculated refractive index varies between 1.65 and 2.15 throughout the spectral region considered. The dispersion parameters such as oscillator energy, dispersion energy, and static and high frequency refractive index were determined in regard to the Wemple DiDomenico single oscillator model. Finally, some dielectric parameters of material such as relaxation time, dissipation (loss) factor, volume and surface energy loss functions and optical conductivity were calculated.
Paslanmaz çelik elyaf takviyeli alüminyum kompozit malzemelerde yorulma çatlak ilerlemesi
(Selçuk Üniversitesi Fen Bilimleri Enstitüsü, 2006) Eskizeybek, Volkan; Avcı, Ahmet
Bu çalışmada, paslanmaz çelik/alüminyum merkez çatlaklı levhaların yorulma davranışı ve kırılma parametreleri deneysel olarak incelendi. Kompozit malzeme, 2024 Al levhaların tek yönlü ve sürekli formda AISI 302 paslanmaz çelik teller ile takviye edilmesiyle sıcak pres yöntemi kullanılarak üretildi. Daha sonra ASTM E-647 standartlarına uygun olarak numuneler hazırlandı ve bu numuneler üzerine a/w=0.4 oranında merkez çatlağı farklı açılarda (0Âº,15Âº,30Âº,45Âº,60Âº,75Âº) açılarak yorulma yükü etkisi altında kırılma davranışı incelendi. Deneyler sırasında yorulma çatlak başlangıcı, yorulma çatlak büyüme hızı (da/dN), çatlak ağzı açılma miktarı, gerilme şiddet faktörleri ve enerji boşalma hızı araştırıldı. Çatlak büyüme hızı ve çatlak ağzı açılma miktarı çatlak geometrisi ile ilgili bir hasar parametresi olarak kullanıldı. Sonuçlarda, çatlak büyüme hızı; çevrimsel gerilim şiddet faktörü (â K) ve enerji boşalma miktarı (â G) ile kontrol edilmiştir. Lineer Elastik Kırılma Mekaniği (LEKM) ve Elasto-Plastik Kırılma Mekaniği (EPKM) ile bulunan sonuçlar karşılaştırıldı.
Physical deposition of carbon doped titanium nitride film by DC magnetron sputtering for metallic implant coating use
(ELSEVIER SCIENCE BV, 2014) Sedira, Sofiane; Achour, Slimane; Avci, Ahmet; Eskizeybek, Volkan
Alloys exposed to tissue environment are at risk to corrosive breakdown. The corrosion behaviour of carbon doped titanium nitride films was studied. The C-TiN films were deposited by DC magnetron sputtering. The obtained films were investigated to be used as protective layers for medical implants. The films were analysed using XRD, SEM with EDX, FTIR, Raman, UV-vis and potentiodynamic polarization. Analysis indicated that doping with carbon in low concentration led to form titanium carbide. The measured values of corrosion current densities (I-corr, (substrate) = 2.020 mu A/cm(2), I-corr, (coating) = 0.175 mu A/cm(2)) indicate that the deposited films improved the corrosion resistance of the pure titanium. Comparison between the corrosion current densities of two samples (uncoated and coated pure titanium) showed a reduction of 91% in corrosion current density for coated Ti compared to the uncoated one. (C) 2014 Elsevier B. V. All rights reserved.
Poli-o-fenilendiamin/CdO nanokompozitlerinin sentezi ve karakterizasyonu
(Selçuk Üniversitesi Mühendislik-Mimarlık Fakültesi, 2012) Akgül, Eda; Aktaş, Funda; Eskizeybek, Volkan
Bu çalışmada, poli-o-fenilendiamin polimeri (POPD) ve farklı mol oranlarında CdO nanoparçacıkları içeren POPD/CdO nanokompozitleri sulu dietilen glikol çözeltisi ortamında kimyasal polimerizasyon yöntemi ile sentezlenmiştir. Sentezlenen polimer ile nanokompozitler Fourier transform infrared spektroskopi, diferansiyel taramalı kalorimetre, UV-Görünür bölge spektroskopisi, taramalı elektron mikroskobu analizleri ile yapısal ve morfolojik olarak incelenmiş ve dört nokta yöntemi ile elektriksel iletkenlik ölçümleri yapılmıştır. Nanoparçacık varlığındaki kimyasal polimerizasyon ile elde edilen yapıların polimer ile nanoparçacığın basit bir karışımı olmadığı, polimer ile nanoparçacıklar arasında konjügasyonun ve elektron yoğunluğunun değişmesine neden olacak kuvvetli etkileşimlerin söz konusu olduğu nanokompozit yapıların sentezlendiği ve nanokompozitlerin iletkenlik değerlerinin polimerin iletkenliğinden daha yüksek olduğu belirlenmiştir. Ayrıca nanokompozitin sentezlenmesi sırasında kullanılan OPD/CdO oranlarına bağlı olarak termal kararlılığın değiştiği, bu oranın 2/1 olması ile maksimum termal kararlılığın elde edildiği görülmüştür. Taramalı elektron mikroskobu ile yapılan morfolojik incelemeler, POPD homopolimerinin küresel yapıya sahip CdO nanoparçacıkların etrafında birikerek nanoparçacıkları kapladığını göstermektedir.
Preparation and mechanical properties of carbon nanotube grafted glass fabric/epoxy multi-scale composites
(TAYLOR & FRANCIS LTD, 2017) Eskizeybek, Volkan; Avci, Ahmet; Gulce, Ahmet
In the present paper, carbon nanotubes (CNTs) were chemically grafted onto surfaces of the amino silane-treated glass fabric by a novel chemical route for the first time to create 3D network on the glass fibers. The chemical bonding process was confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy. The glass fabric/CNT/epoxy multi-scale composite laminates were fabricated with the CNT grafted fabrics using vacuum assisted resin infusion molding. Tensile tests were conducted on fabricated multi-scale composites, indicating the grafting CNTs on glass fabric resulted a decrease (11%) in ultimate tensile strength while toughness of the multi-scale composite laminates were increased up to 57%. Flexural tests revealed that the multi-scale composite laminates prepared with CNT grafted glass fabric represent recovering after first load fall. The interfacial reinforcing mechanisms were discussed based on fracture morphologies of the multi-scale composites.
Preparation of a New Polyaniline/CdO Nanocomposite and Investigation of Its Photocatalytic Activity: Comparative Study under UV Light and Natural Sunlight Irradiation
(AMER CHEMICAL SOC, 2013) Gulce, Handan; Eskizeybek, Volkan; Haspulat, Bircan; Sari, Fahriye; Gulce, Ahmet; Avci, Ahmet
Polyaniline (PANI)/CdO nanocomposite was prepared for the first time in aqueous diethylene glycol solution medium, by chemical oxidative polymerization, and its photocatalytical activity was studied. Optical analysis of the new PANI/CdO nanocomposite revealed that electron densities and bond energies of the PANI homopolymer decreased after modifying with CdO nanoparticles, due to interactions between PANI chains and CdO nanoparticles. The prepared PANI/CdO nanocomposite exhibits excellent photocatalytic activity under both UV light and natural sunlight irradiation. The photocatalytic decolorization rate was increased up to 7 times after CdO addition, compared to the decolorization rate of PANI homopolymer under UV light irradiation. During the photocatalytic activity investigations, methylene blue and malachite green dyes were photocatalytically decolorized under natural sunlight irradiation with 99% efficiency by the use of 0.4 mg/mL PANI/CdO nanocomposite as photocatalyst. Furthermore, the PANI/CdO photocatalyst retains its efficiency with slight decreases upon being reused up to five times.
Preparation of polyaniline/ZnO nanocomposites by using arc-discharge synthesized zno nanoparticles and photocatalytic applications
(Selçuk Üniversitesi Mühendislik-Mimarlık Fakültesi, 2012) Eskizeybek, Volkan; Gülce, Handan; Gülce, Ahmet; Avcı, Ahmet; Akgül, Eda
Polyaniline (PANI) and PANI/ZnO nanocomposites were synthesized by the chemical oxidative polymerization of aniline and aniline with the presence of ZnO nanoparticles, respectively. The ZnO nanoparticles synthesized by arc-discharge method were used in this study to produce PANI/ZnO nanocomposites. Aniline/ZnO nanoparticles molar ratio was changed to investigate the effect of ZnO nanoparticles to the characteristic of the PANI. The scanning electron microscope analysis showed that ZnO nanoparticles were completely dispersed in PANI matrix homogeneously. It is revealed that shifting to the higher wavenumbers occurred by the increasing ZnO nanoparticle content in fourier transform infrared spectroscopy analysis. Furthermore, degradation of malachite green in aqueous solution was carried out with the prepared nanocomposites under ultraviolet irradiation. The experimental results showed that 1.2 g/L of the nanocomposite could catalyze green solution above 98% after 180 min of irradiation.
Preparation of the New Polyaniline/ZnO Nanocomposite and Its Photocatalytic Activity for Degradation of Methylene Blue and Malachite Green Dyes Under UV and Natural Sun Lights Irradiations
(ELSEVIER, 2012) Eskizeybek, Volkan; Sarı, Fahriye; Gülce, Handan; Gülce, Ahmet; Avcı, Ahmet
A new polyaniline (PANI) homopolymer and PANI/ZnO nanocomposite have been successfully synthesized in aqueous diethylene glycol solution medium via the chemical oxidative polymerization of aniline. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, FTIR spectra, UV-vis spectroscopy measurements were used to characterize the resulting PANI homopolymer and PANI/ZnO nanocomposite photocatalysts. The photocatalytic activities of PANI homopolymer and PANI/ZnO nanocomposites were investigated by the degradation of methylene blue (MB) and malachite green (MG) dyes in aqueous medium under natural sunlight and UV light irradiation and the efficiency of the catalysts have been discussed in detail. Results indicate that the addition of the ZnO nanoparticles to the PANI homopolymer enhance the photocatalytic efficiency under natural sunlight irradiation and a little amount of PANI/ZnO nanocomposite photocatalyst (0.4 g/L) degrades both of the dye solutions (MB or MG) with 99% efficiency after 5 h of irradiation under natural sunlight.
Removal of chromium (VI) using activated carbon-supported-functionalized carbon nanotubes
(SPRINGER HEIDELBERG, 2015) Parlayici, Serife; Eskizeybek, Volkan; Avci, Ahmet; Pehlivan, Erol
The powdered activated carbon (AC) supported by carbonaceous nano-adsorbents were examined to remove hexavalent chromium [Cr(VI)] from aqueous solution The adsorption behaviour of micro-level concentration of Cr(VI) on those nano-adsorbents was investigated as a function of the experimental conditions such as the contact time, the pH, the dosage of adsorbent, and the initial concentration of Cr(VI). The structural characterization of the adsorbents was accomplished by Fourier transform infrared spectroscopy and scanning electron microscopy. Adsorption isotherms including Freundlich and Langmuir have been applied to study the equilibrium of the adsorption behaviour and identify the adsorption capacity of the activated carbon-functionalized multiwalled carbon nanotubes (AC/f-MWCNTs) and activated carbon-functionalized carbon nanospheres (AC/f-CNSs). Langmuir isotherm model showed that the adsorption process was monolayer type under working with an adsorption capacity of 113.29 and 105.48 mg/g, respectively, for AC/f-MWCNTs and (AC/f-CNSs).
Static and dynamic mechanical responses of CaCO3 nanoparticle modified epoxy/carbon fiber nanocomposites
(ELSEVIER SCI LTD, 2018) Eskizeybek, Volkan; Ulus, Hasan; Kaybal, Halil B.; Sahin, Omer S.; Avci, Ahmet
Matrix modification of carbon fiber reinforced polymer composites with nanoparticles is an effective way to improve its matrix dominated properties. After nanoparticle modification, understanding mechanical properties is important in structural applications, and improvement of such properties can lead to the usage in the wider fields. This study aimed to investigate experimentally static and dynamic mechanical behaviors of CaCO3 modified epoxy/carbon fiber nanocomposites. For this, we filled various amounts of CaCO3 nanoreinforcements into the epoxy matrix, and the nanoreinforced epoxy was used to impregnate carbon fabrics (CF) by utilizing vacuum assisted resin infusion method (VARIM). The prepared fiber reinforced nanocomposites were subjected to tensile, bending and low velocity impact loadings. As a result of all experiments, the tensile strength of CF/epoxy nanocomposites increased about 48% with the addition of 2 wt% CaCO3 nanoreinforcement. The flexural strength enhancements were also determined as 47% for the same CaCO3 nanoreinforcement loading. Besides, by utilizing low-velocity impact tests, we revealed that the CaCO3 nanoparticle reinforced CF/epoxy nano composites exhibited higher impact performances compared to neat CF/epoxy composites. The resulting fracture morphologies were examined by electron microscopy to disclose related mechanical toughening mechanisms. Based on the morphological analysis, crack pinning, crack deflection and debonding of nanoparticles were the primary reasons leading to the improvement of toughness. The authors concluded that the addition of the CaCO3 nanoreinforcements in CF/epoxy composites has significantly influenced the mechanical and physical properties of the nanocomposites.

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