Browsing by Author "Ozmeral, Nimet"

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Citation - WoS: 5
Citation - Scopus: 6
Appraisal of Inorganic and Lignocellulosic Organic Shell Wastes as a Green Filler in Epoxy-Based Hybrid Composites
(Elsevier, 2025) Ahmetli, Gulnare; Kocaman, Suheyla; Soydal, Ulku; Kocak, Beril; Ozmeral, Nimet; Musayev, Nijat
Hybrid composites are now becoming increasingly important regarding economic and ecological compatibility. This study presented the research results that evaluate the feasibility of using cherry pit shell (CPSh) and chicken eggshell (ChESh) natural wastes as a new hybrid filler mixture for the first time. CPSh and ChESh can reduce the composite material cost and increase the biobased content. CPSh was treated with a 5 % NaOH alkali solution to enhance the lignocellulosic filler-matrix interfacial interaction. Hybrid green organic and inorganic fillers were used in the epoxy matrix (ER). Morphological, water absorption, thermal, and mechanical performance of hybrid composites were investigated. The tensile strength of ER increased max. by 5.73, 7.3, 17.98, and 14.27 % in the case of raw CPSh, ChESh, and hybrid filler mixtures at 1:1 and 1:3 wt mixing ratios of alkali-treated CPSh (NaOHCPSh) and ChESh, respectively. The composites' thermal stability and dynamic-mechanical properties in different aging environments (seawater and hydrothermal) were examined by thermogravimetric analysis (TGA) and dynamic-mechanical analysis (DMA). Hydrothermal was the most affected aging condition on the composite properties. In addition, ANOVA is applied to find the significant effect of different weight percentages of hybrid fillers on the mechanical properties of composites.
Citation - WoS: 2
Citation - Scopus: 2
Elastic and Acoustic Properties Determination of Epoxy/Polystyrene Mud Waste Hybrid Composites by Ultrasonic Method
(Wiley, 2025) Oral, Imran; Ozmeral, Nimet; Ahmetli, Gulnare; Guzel, Hatice
Ultrasonic methods are more sensitive to defects such as voids, pores, and discontinuities that can diminish the true elastic and acoustic properties of materials compared to destructive testing. Therefore, the elastic properties and some acoustic properties of the epoxy phenol novolac modified with polystyrene (EPN-PS) matrix-based nano- and hybrid composites were determined for the first time using ultrasonic method. Montmorillonite-type nanoclay (NC) and industrial red mud waste (RMW) at a rate of 1-4 and 15-35 wt% respectively, were used as fillers in the composite preparation. According to the results, the highest elastic coefficient values (L = 8.14 GPa, G = 1.76 GPa, K = 5.79 GPa and E = 4.80 GPa) were obtained in the EPN-PS/NC1 (with 1 wt% NC) nanocomposite sample compared to the elastic properties of pure EPN and EPN-PS, while the highest elastic coefficient values (L = 8.97 GPa, G = 2.19 GPa, K = 6.06 GPa, and E = 5.86 GPa) among hybrid composites (HC) were obtained for the HC35 containing 2 wt. % NC and 35 wt% RMW. Due to both its high elastic and good acoustic properties, wall panels and floors produced using HC35 hybrid composite can be used for sound insulation in noisy environments.Highlights First evaluation of the acoustic characteristics of epoxy phenol novolac modified with polystyrene-nanoclay/red mud waste (EPN-PS-NC/RMW) composites. NC4 with 4 wt% nanoclay showed the lowest elastic and acoustic properties. Nanoclay ratio above 1 wt% reduces elastic and acoustic properties. The increasing RMW ratio in hybrid composites increases elastic properties. High elastic and acoustic properties make HC35 ideal for sound insulation.
Citation - WoS: 6
Citation - Scopus: 6
Hybrid Epoxy Composites Based on Tire Waste-Derived Carbon Black and Eggshells With Enhanced Properties and Aging Life in Different Environmental Conditions
(Elsevier Science Sa, 2025) Ahmetli, Gulnare; Kocaman, Suheyla; Musayev, Nijat; Gasimov, Javidan; Ozmeral, Nimet
Chicken eggshells (ChESh), are an unusual type of biomaterial and huge biological waste because of their rapid formation. In addition, carbon black (CBpyr) recycled from tire wastes by pyrolysis is a significant raw material for obtaining valuable products. This study investigated the effects of the hybrid fillers (CBpyr and ChESh) on the composite properties. The hybrid filler mixture was created in different weight ratios and incorporated into the epoxy matrix (ER) at 15-35 wt%. The 25 wt% hybrid filler ratio proved to be the most suitable for enhancing the mechanical properties. The tensile strength was 104, 99, and 77 MPa for hybrid composites (HC) in the CBpyr: ChESh hybrid filler at 1:1, 1:3, and 3:1 wt ratios. A 1:1 hybrid filler wt ratio was more effective in enhancing fire resistance properties, while a 1:3 ratio was better for achieving thermal resistance of unaged HCs. All 25 wt% HCs had higher storage and loss modulus values than ER. The maximum weight gains over 30 days in pure water, seawater, and hydrothermal aging conditions were found to be 0.99-1.4 %, 0.86-1.18 %, and 1.64-2.63 % for ER and HCs. In contrast to the unaged composite, the composite with the hybrid filler at a 1:3 wt ratio (HC(1:3)) exhibited higher tensile strength under these aging conditions. The mechanical properties were most affected by hydrothermal aging. Also, a lower glass transition temperature (Tg) value reduction was found for the aged HC (1:3). This composite is the most resistant to UV rays.
Citation - WoS: 4
Citation - Scopus: 4
Multi-Walled Carbon Nanotubes and Graphene Oxide-Based Epoxy Hybrid Nanocomposites: Investigation of Nanofiller Modification Effect
(Elsevier, 2025) Ahmetli, Gulnare; Kocaman, Suheyla; Musayev, Nijat; Ozmeral, Nimet; Isik, Murat
Multi-walled carbon nanotubes (MWCNTs) are important nanomaterials utilized in various research and technological applications. Graphene oxide (GO) is another fascinating material that can be effectively applied in various fields, including nanocomposite materials, energy storage, biomedical applications, and catalysis. This study first examined the effect of hybridizing a 1:1 wt ratio mixture of modified carboxyl-functionalized MWCNTs (MWCNTCOOH) and graphene oxide (GO) nanofillers on the properties of novel epoxy resin (ER)based composites. GO was synthesized from graphite. The surface modification of both nanoparticles was performed using polyaniline (PANI) and/or ionic liquid 1-butyl-3-methylimidazolium bromide (IL). The hybrid reinforcement ratio in ER ranged from 0.5 % to 2 % by weight. At the reinforcement ratio of 1.5 wt%, the increase in tensile strength of all nanocomposites compared to ER varied between 22.2 % and 62.8 %. Modification with PANI showed improved mechanical, thermal, and electrical conductivity, as well as enhanced durability in hot water compared to IL. Additionally, PANI and IL further increased the chemical resistance of the hybrid nanocomposites. The highest and lowest glass transition temperatures (Tg) correspond to the 1.5 wt% PANIMWCNTCOOH/ GO (108.60 degrees C) and the IL-MWCNTCOOH/ GO (97.99 degrees C) hybrid nanocomposites, respectively. The electrical conductivity ranges in value from 6.9 x 10-8 to 1.22 x 10-4 S/cm, depending on the hybrid nanocomposite type. The nanocomposites demonstrated superior UV resistance compared to ER, showing an absorbance range of 0.305 to 1.391 a.u. Furthermore, the ANOVA test demonstrated the impact of the hybrid filler type and ratio on the nanocomposite's mechanical properties.
Citation - WoS: 1
Citation - Scopus: 2
Sustainable Biobased Composites: Fumaric Acid-Based Epoxy Resin Synthesis and Modified Natural Waste Reinforcements
(Elsevier, 2025) Kocaman, Suheyla; Ahmetli, Gulnare; Ozmeral, Nimet
The increasing demand for sustainable alternatives to petroleum-based polymers has accelerated the development of biocomposites to mitigate environmental impact. In this study, a novel bio-based epoxy resin (EFA) was synthesized via the reaction of fumaric acid (FA) and epichlorohydrin (ECH), and characterized using FT-IR, 1H NMR, viscosity, mass spectrometry, and epoxy group analysis. Apricot kernel shell (APKSh), an agricultural waste, was used as a natural reinforcement, modified with citric acid (CA) and levulinic acid (LA) to improve interfacial compatibility. Composites were produced with filler contents ranging from 5 to 30 wt% and tested for FT-IR, SEM, TGA, DMA, mechanical, thermal, and surface properties. The 15 wt% CA-modified composite exhibited a tensile strength of 105.7 MPa, an elastic modulus (e-modulus) of 8.7 GPa, and a Shore D hardness of 80, representing up to 222 % improvement in tensile strength and 107 % improvement in hardness compared to the neat ER-EFA (7:3 weight ratio). The LA-APKSh composites showed a char residue of 26.9 % at 800 degrees C and a Tg value of 106.01 degrees C. Contact angle (C.A.) measurements revealed enhanced hydrophobicity, with values exceeding 99.6 degrees for CAAPKSh composites. The weight gain data in seawater indicated that all composites had higher values compared to the neat ER-EFA matrix (7:3 weight ratio). ANOVA analysis highlighted the influence of filler type and content on composite properties. This study presents a promising approach to developing high-performance, eco-friendly epoxy composites using chemically modified lignocellulosic waste.