Profile URL: https://hdl.handle.net/20.500.13091/11538
Job Title:Prof. Dr.
Email Address:gahmetki@ktun.edu.tr
Main Affiliation:02.01. Department of Chemical Engineering
Status: Current Staff
ORCID:
0000-0002-9381-4139
0000-0002-9381-4139Scopus ID:
35607815600
35607815600YÖK Akademik: 3A1E4AEF51ACCECE
Web of Science ID:
JVM-8971-2024
JVM-8971-2024Name Variants:
Ahmetli, G. Ahmetli, Gulnare
59 results
Scholarly Output Search Results
Now showing 1 - 10 of 59
Conference Object Evaluation of Rubber Wastes in Composites(2022) Özmeral, Nimet; Türkben, Merve; Kocaman, Süheyla; Soydal, Ülkü; Ahmetli, GülnareThe composition of solid waste is divided into several types, including rubber waste. About 17,000,000 tons of scrap tires are generated in the world every year, and this amount is around 180,000-300,000 tons per year in Turkey. Most of the rubber waste produced comes from automobile, truck, and motorcycle tires. Only 40% of rubber waste is recyclable, excluding energy recovery and landfill applications. In 2018, the amount of rubber waste burned for energy recovery and disposed of in landfills was 7.2% and 3.4%, respectively. Reliable industrial technology and processes are needed to reuse and recycle these wastes. Processed waste can be transformed into cheaper and more sustainable materials. The cycle of producing new tires from used, worn rubber waste increases sustainability. The use of worn tires and scrap tire granules in new products is significantly. It helps reduce the carbon footprint by one-third compared to products made without recycled materials. Using waste tires as filler material to create new composites seems to be one of the most important methods of sustainable management. In this way, it can contribute to the reduction of the waste tire rubber amount after consumption. In this study, two-type of rubber wastes: ground tire rubber (GTR) and ethylene propylene-diene monomer rubber (EPDM) was used as reinforcement in an epoxy matrix. Bisphenol A-type epoxy resin and its blend with polyurethane-modified epoxy in a 1:1 ratio were used as matrices. The effect of rubber and epoxy matrix type on composites’ mechanical properties was investigated. Also, the effect of water sorption and low temperature on mechanical properties was studied.Article Exploring the Influence of Various Filler Modification Techniques on the Biocomposites Properties Derived From Lignocellulosic Hazelnut Waste Shells(Elsevier, 2025-12-01) Ahmetli, Gulnare; Kocaman, Suheyla; Yuksel, Busra Donmez; Ulusoy, Pinar; Musayev, Nijat; Dönmez Yüksel, BüşraBiocomposites exhibit a wide range of properties and can compete with non-biodegradable polymers across various industrial fields. This study presented research results using hazelnut shell waste (HShW) as a biofiller in an epoxy matrix. HShW was modified using sodium hydroxide and several acids, including ethylenediaminetetraacetic (EDTA), acetic (AA), acrylic (AcA), and linoleic (LA). The modification process increased cellulose content, while lignin and hemicellulose contents decreased. This study explored the effects of filler content and modification type on the composites' mechanical, thermal, dynamic mechanical, water sorption, chemical resistance, and hygrothermal aging properties. The distinct X-ray diffraction (XRD) peaks around 22 degrees confirm that Cellulose I retains its original crystal structure within the composites. All modifications improved the tensile strength of the biocomposites, particularly at 20-30 wt%, ranging from 4.65 % to 53.49 %. The LA-HShW composites displayed the highest tensile strength (101-132 MPa), thermal stability, and glass transition temperature (Tg) values of 101.1 degrees C (DMA) and 66.4 degrees C (DSC). The AcA-and LA-modified HShW composites exhibited the lowest mass loss rate at 379.2 degrees C among the composite materials. All composites demonstrated greater resistance to alkali and acids such as hydrochloric and sulfuric, while showing lower resistance to acetone. In addition, hygrothermal aging increased moisture uptake (2.45-5.68 %) in biocomposites and reduced Tg values. A decrease in the Tg values of DMA and DSC was between 4.80 and 18.71 % and 7.01-18.29 %, respectively. The 20 wt% LA-HShW composite demonstrated significantly greater stability to aging, exhibiting the highest storage modulus (0.85 GPa), loss modulus (0.06 GPa), and DSC Tg (58.2 degrees C) compared to the other composites.Master Thesis Lastik ve Epdm Kauçuğu Atıklarının Kompozit Malzemede Kullanımı(Konya Teknik Üniversitesi, 2019) Türkben, Merve; Ahmetli, GülnareBu çalışmada 4 farklı atık lastikten (araba, traktör, otobüs, kamyon) elde edilen atık lastik tozu (LA) ve EPDM kauçuğu tozu (EPDM) epoksi reçinede dolgu malzemesi olarak seçilmiştir. Çalışmada 3 tür epoksi reçine: NPER 450 (kauçukla modifiye), NPEK114 (bisfenol-A), NPER 133L (poliüretanla modifiye)'nin 1:1 oranında karışımları matris olarak kullanılmıştır. LA ve EPDM, epoksi reçineye kütlece % 10-50 oranlarında ilave edilmiş, dolgu maddesi miktarının ve epoksi reçine türünün kompozit özelliklerine etkisi incelenmiştir. Kompozitlerin morfolojisi ve yapısı Taramalı Elektron Mikroskobu (SEM) ve X-ışını Kırınımı (XRD) ile karakterize edilmiştir. Kompozitlerin mekanik özellikleri(çekme dayanımı, çekme uzaması, elastisite modülü ve sertlikleri) tayin edilmiştir. LA kompozitlerinin mekanik ve termal özellikleri EPDM kompozitlerinden yüksek bulunmuştur. Reçine karışımlarında ise en iyi sonuçlar NPER 133L-NPEK 114 ile elde edilmiştir. Dolgu olarak EPDM için en uygun oran %20, LA için %30 belirlenmiştir.Article Citation - WoS: 37Citation - Scopus: 47Behaviour of Waste Polypropylene Pyrolysis Char-Based Epoxy Composite Materials(SPRINGER HEIDELBERG, 2019-12-10) Soğancıoğlu, Merve; Yel, Esra; Ahmetli, GülnareIn this study, polypropylene (PP) plastic wastes were pyrolysed. Solid pyrolysis product (char) was used as filler material for the preparation of epoxy composite. 300, 400, 500, 600 and 700 degrees C were selected as final pyrolysis temperatures. Solid pyrolysis product (char) was analysed by elemental, FTIR, SEM, BET and TGA analysis. The epoxy composite samples were prepared with char obtained from pyrolysis. Mechanical properties of composites were analysed by hardness, tensile strength, elongation at break, electrical conductivity tests to explain the effects of pyrolysis temperature and char doses over composite properties. Thermogravimetric properties of composites were determined by TGA analyses. The water absorption behaviour of composite samples was determined by water adsorption test. Epoxy composite produced from PP char obtained under 300 degrees C showed the most ideal behaviour.Article Citation - WoS: 50Citation - Scopus: 55Effects of Various Methods of Chemical Modification of Lignocellulose Hazelnut Shell Waste on a Newly Synthesized Bio-Based Epoxy Composite(SPRINGER, 2020-02-12) Kocaman, Süheyla; Ahmetli, GülnareIn this study, a novel bio-based epoxy resin (ESA) with curable double bonds was synthesized by esterification reaction between sebacic acid (SAc) and epichlorohydrin (ECH). Its chemical structure was confirmed by FT-IR and H-1 NMR. Untreated, alkali treated, acrylic acid (AcA)- and acetic anhydride (AA) modified hazelnut shell waste (HSh) were used as inexpensive reinforcing materials in the ESA matrix system. The composites were prepared with HSh in varied per cent values (10-50 wt%) using the casting technique. The effects of chemical modification and amount of reinforcement materials on the properties of the composites were investigated. The composites were characterized using mechanical tests, as well as SEM, XRD, TGA, and contact angle measurement. The morphological results indicate an improvement in adhesion between the HSh fillers and ESA matrix upon chemical treatments. The modified HShs reinforced composites showed an increase of 7.7-46.2% in elongation at break when compared to the untreated HSh reinforced composite at more appropriate 20 wt% of filler. Also, tensile strengths of all chemically modified HSh composites are higher than that obtained with neat ESA and untreated HSh composites. It was observed that 20 wt% AA-modified HSh composite exhibited higher tensile strength (66 MPa) and elasticity modulus E (6.72 GPa) values. The TGA analysis showed that the HShs can significantly improve the thermal stability of neat ESA. Vicat softening temperature (VST) of composites was obtained higher than epoxy matrix. Additionally, all composites exhibited hydrophobic surfaces. The incorporation of HSh fillers reduces the wetting and hydrophilicity of synthesized epoxy resin.Article Citation - WoS: 5Citation - Scopus: 6Appraisal of Inorganic and Lignocellulosic Organic Shell Wastes as a Green Filler in Epoxy-Based Hybrid Composites(Elsevier, 2024) Ahmetli, Gulnare; Kocaman, Suheyla; Soydal, Ulku; Kocak, Beril; Ozmeral, Nimet; Musayev, NijatHybrid 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.Article Citation - WoS: 10Citation - Scopus: 13Preparation and Ultrasonic Characterization of Modified Epoxy Resin/Coconut Shell Powder Biocomposites(WILEY, 2021-10-18) Oral, İmran; Kocaman, Süheyla; Ahmetli, GülnareA new bio-based epoxy resin (BER) is produced by the esterification reaction between sebacic acid (SAc) as bio-based acid and epichlorohydrin (ECH). The epoxy resin (ER) is modified with the BER. The biocomposites are prepared using untreated coconut shell powder (CSP), modified coconut shell powder (MCSP), and MER. The CSP and MCSP particles are mixed with MER in varied compositions (10-50 wt%) for preparation of the MER/CSP and MER/MCSP biocomposites. The influences of CSP and MCSP bio-fillers amounts on the physical properties (density, elastic constants, acoustic impedance, ultrasonic micro-hardness, and attenuation coefficient) of biocomposites are investigated using the ultrasonic pulse-echo overlap method (PEOM). It was seen that the densities, both ultrasonic longitudinal and shear waves' velocity values of obtained biocomposites were higher than those of the MER. All elastic moduli of the MER/MCSP biocomposites have higher values than of the neat MER and MER/CSP biocomposites.Article Citation - WoS: 7Citation - Scopus: 7New Biobased Chitosan-Modified Peach Kernel Shell Composites and Examining Their Behavior in Different Environmental Conditions(Elsevier B.V., 2024-11-01) Ahmetli G.; Soydal U.; Kocaman S.; Özmeral N.; Musayev N.; Ozmeral, Nimet; Musayev, Nijat; Soydal, Ulku; Ahmetli, Gulnare; Kocaman, SuheylaBisphenol A-type epoxy (ER) is a versatile synthetic polymer preferred for composite materials but non-biodegradability raises challenges for composites recycling in particular. The present study first investigated the potential usability of peach kernel shells (PKSh) waste as fillers in ER to decrease the cost of composite materials and increase their bio-based content. Different chemical modifications were performed to increase the poor compatibility between the hydrophilic lignocellulosic filler and the hydrophobic polymer matrix. The modified PKShs were obtained by alkali treatment (NaOH-PKSh), coating with biopolymer chitosan (CTS-PKSh), and cross-linking of CTS with glutaraldehyde (GA@CTS-PKSh). The aging of composites is a highly topical subject given the increasing use of composites in structural applications in many industries. The composites' thermal stability and dynamic-mechanical properties in different aging environments (water, seawater, and hydrothermal) were examined. The order of the aging conditions in terms of their effects on the composite properties was: hydrothermal > water > seawater. The ER/GA@CTS-PKSh composite was the most resistant to all environmental conditions. The tensile strength of epoxy matrix (ER) increased max. by 7.78 %, 21.11 %, 42.22 %, and 45.46 % in the case of raw, NaOH-PKSh, CTS-PKSh, and GA@CTS-PKSh fillers, respectively. Composites showed higher absorption in both UV and visible regions. © 2024Article Citation - WoS: 1Citation - Scopus: 2Sustainable Biobased Composites: Fumaric Acid-Based Epoxy Resin Synthesis and Modified Natural Waste Reinforcements(Elsevier, 2025-08-01) Kocaman, Suheyla; Ahmetli, Gulnare; Ozmeral, NimetThe 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.Conference Object Investigation of Properties of Renewable Films Prepared With Aloe Vera Gel(Faculty of Engineering and Architecture at Erzurum Technical University, 2021) Soydal, Ülkü; Yıldırım, Murat; Okçuoğlu, Merve Ceren; Ahmetli, GülnareAloe vera plant, known as yellow patience in Turkey, is a plant known for centuries in many ancient civilizations and used in various diseases and skin problems due to its healing power. Among its many health benefits, wound healing mainly, hypoglycemic or antidiabetic, hepatoprotective, anti inflammatory, immune-boosting and gastroprotective, antioxidant, antimicrobial, antiviral and antifungal properties have also been reported. On the other hand, most of the monomers of polymer films produced in the industrial field are of petroleum origin. The fact that the depleting petroleum resources are both expensive and bring environmental problems such as waste problems lead scientists to seek cheaper and renewable resources. Therefore, synthesis studies of bio - based polymeric materials from different renewable sources such as oil - based sources are becoming increasingly important. In this study, aloe vera plant gel (AV), was used as a modifier for the preparation of film materials in biobased acrylated epoxidized soybean oil (AESO) resin matrix. Films were formed by adding aloe vera gel at different ratios (0 %, 10 %, 20 %, 30 %, 40 %, 50 % by weight). The effect of AV amount on pH change, swelling – solubility - water content, antibacterial and mechanical properties of the films were investigated. The prepared AV / AESO films were effective against Gram - positive (Staphylococcus aureus and Enterococcus faecalis) and Gram - negative (Escherichia coli and Klebsiella pneumoniae) bacteria. Finally, from the pH tests performed on the films, values between 7.23 and 7.35 were obtained. Accordingly, it showed that the films were compatible with the skin.
Research Topics
Domains
Physical Sciences
Fields
Materials ScienceEngineering
Subfields
Polymers and PlasticsMechanical Engineering
Specific Research Areas
Polymer Nanocomposites and Properties
Natural Fiber Reinforced Composites
Epoxy Resin Curing Processes
Polymer composites and self-healing
Fiber-reinforced polymer composites
Sustainable Development Goals
12RESPONSIBLE CONSUMPTION AND PRODUCTION
10
Research Products
7AFFORDABLE AND CLEAN ENERGY
9
Research Products
9INDUSTRY, INNOVATION AND INFRASTRUCTURE
9
Research Products
6CLEAN WATER AND SANITATION
6
Research Products
11SUSTAINABLE CITIES AND COMMUNITIES
3
Research Products
14LIFE BELOW WATER
2
Research Products
2ZERO HUNGER
2
Research Products
3GOOD HEALTH AND WELL-BEING
2
Research Products
13CLIMATE ACTION
2
Research Products
4QUALITY EDUCATION
1
Research Products
Documents
85
Citations
1806
h-index
23
Documents
85
Citations
1798
Publication Collaboration
| Affiliation Name | Count |
|---|---|
| Selçuk University | 66 |
| Konya Technical University | 43 |
| Necmettin Erbakan University | 9 |
| Konya Food and Agriculture University | 3 |
| Yeditepe University | 1 |
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Data obtained from OpenAlex
| Journal | Count |
|---|---|
| Industrial Crops and Products | 4 |
| Journal of Applied Polymer Science | 4 |
| International Journal of Biological Macromolecules | 4 |
| International Journal of Environmental Science and Technology | 3 |
| JOURNAL OF APPLIED POLYMER SCIENCE | 3 |
Current Page: 1 / 6
Scholarly Output
59
Articles
43
Views / Downloads
175/144
Supervised MSc Theses
6
Supervised PhD Theses
0
WoS Citation Count
460
Scopus Citation Count
527
Patents
0
Projects
0
WoS Citations per Publication
7.80
Scopus Citations per Publication
8.93
Open Access Source
18
Supervised Theses
6
Scopus Quartile Distribution
Competency Cloud
