Browsing by Author "Soydal, Ülkü"

Now showing 1 - 13 of 13

Citation - WoS: 1
Badem Kabuğu Atığı Dolgulu Epoksi Biyokompozit Özelliklerinin İncelenmesi
(Pamukkale Univ, 2023) Özmeral, Nimet; Kocaman, Süheyla; Soydal, Ülkü; Ahmetli, Gülnare
Bu çalışmada biyobazlı kompozit malzeme elde etmek için dolgu malzemesi olarak badem kabuğu atığı (BK), saf (ER) ve atık polistirenle modifiye bisfenol-A tipi epoksi reçine (ER-PS) kullanılmıştır. BK'nin modifikasyonu, NaOH ve linoleik asit (LnA) ile gerçekleştirilmiştir. BK'nin karakterizasyonunda Fourier dönüşümlü kızılötesi spektroskopisi (FT-IR), taramalı elektron mikroskopisi (SEM), termogravimetrik analiz (TGA) ve partikül boyut dağılım analizleri kullanılmıştır. Kompozitler, döküm tekniği kullanılarak kütlece %10-20-30-40-50 dolgu oranlarında hazırlanmıştır. Kompozitlerin morfolojisi SEM ile karakterize edilmiştir. Epoksi matris tipi ve BK dolgu oranının kompozitlerin mekanik, termal ve su sorpsiyonu özelliklerine etkileri araştırılmıştır. ER-PS/BK kompozitlerinin çekme mukavemeti ve elastise modül (e-modül) değerleri daha düşük, çekme uzama değerleri ise ER/BK kompozitlerine göre daha yüksek bulunmuştur. En yüksek çekme dayanımı değerleri (95-129 MPa) LnA ile modifiye BK kompozitleri için elde edilmiştir. Hazırlanan ER matrisli kompozitlerin dolgu tipine göre çekme mukavemetleri sırası ile: linoleik asit ile modifiye edilmiş BK (LnA-BK) > NaOH ile muamele edilmiş BK (NaOH- BK) > modifiye edilmemiş BK’dir. En uygun BK oranı kütlece %30 olarak belirlenmiştir. Tüm modifiye BK kompozitlerinin e-modül değerleri epoksi matristen daha yüksek bulunmuştur. Sertlik testi sonuçlarına göre kompozitler arasında önemli bir fark belirlenmemiştir. Kompozitlerin su sorpsiyonu BK oranına bağlı olarak artmış ve mekanik özellikleri zayıflatıcı yönde etki etmiştir.
Coating and Flammability Properties of Modified Epoxy-Based Hybrid Composites
(IKSAD Publications, 2022) Özmeral, Nimet; Kocaman, Süheyla; Soydal, Ülkü; Ahmetli, Gülnare
In this study, phenolic novolac-type epoxy resin (EPN) modified with 4 wt% polystyrene (PS) waste, was used as the polymer matrix (EPN-PS) for the first time. Hybrid composites were prepared using red mud waste (RMW) waste at 15-35 wt% and montmorillonite-type nanoclay (NC) at a 2 wt% constant ratio. RMW was a waste material produced during the production of bauxite alumina with the Bayer process. The modification of NC has been made with tetramethylammonium chloride (TMAC). The NC and RMW particle sizes were determined by Particle Size Distribution Analysis. The average sizes were determined as 1631 d.nm and 1064 d.nm, for NC and modified NC (MNC), respectively. Chemical structures of nanoclays were elucidated by FTIR. The effect of the type and ratio of fillers on the coating and flammability properties of the composites were examined. The corrosion protection properties of the composite coatings were determined by immersion test in 5 wt% NaOH, HCl, and NaCl solutions. Surface morphologies of hybrid composites were examined by scanning electron microscopy (SEM) before and after corrosion tests. In addition, the changes in composite coatings in corrosive environments were also examined with a microscope. The modification of NC and the application of hybrid reinforcement were more effective in corrosion resistance of composite coatings in basic and salty environments. The maximum enhancement of corrosion resistance was achieved at 2 wt% MNC-35 wt% RMW. Combustion of the EPN-PS matrix (115 sec) decreased with adding NC/MNC and RMW, and these composites were extinguished in 69 sec and 47 sec, respectively.
Evaluation of Fatty Acid Waste in the Synthesis of Oligo(ether-Ester)s
(HINDAWI LTD, 2019) Kocaman, Süheyla; Cerit, A.; Soydal, Ülkü; Martı, M. E.; Ahmetli, G.
In this study, the waste of sunflower oil refinement was converted to a fatty acid glycidyl ester (FAGE). An unsaturated oligo(ether-ester) (OEE) was synthesized by ring-opening polymerization using propylene oxide (PO) and FAGE. Oligo(ether-ester) production was achieved with a high yield of 80% at 5 h and 0 degrees C when the mole ratio of PO : FAGE was 1 : 1. Synthesized OEE was characterized by FTIR and several chemical analysis methods. According to the TGA results, T-5, T-10, and T-50 values of OEE-styrene copolymers increased up to a 7 : 3 mole ratio then decreased. The weight losses of these copolymers changed in the range of 3-5%. The data of longitudinal and transversal wave velocities showed that copolymers with styrene had better elastic properties and impact resistances compared to those with pure polystyrene.
Evaluation of Rubber Wastes in Composites
(2022) Özmeral, Nimet; Türkben, Merve; Kocaman, Süheyla; Soydal, Ülkü; Ahmetli, Gülnare
The 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.
Citation - WoS: 26
Citation - Scopus: 26
Influence of Cotton Waste and Flame-Retardant Additives on the Mechanical, Thermal, and Flammability Properties of Phenolic Novolac Epoxy Composites
(SPRINGER, 2021) Kocaman, Süheyla; Soydal, Ülkü; Ahmetli, Gülnare
Phenolic novolac-type epoxy (EPN) resin composites were fabricated by reinforcing with cotton waste (CtW), along with aluminum hydroxide (AH), and boric acid (BA) particles under different filler loadings. For characterization, thermogravimetric analysis, scanning electron microscopy, differential scanning calorimetry, and water sorption tests were performed on the composites. The effects of the CtW, AH, and BA contents on the thermal, flame-retardant, and mechanical properties of the composites were investigated. The triple hybrid additive (CtW:BA:AH) with a ratio of 20:5:10 wt% exhibited the best mechanical and combustion properties. The tensile strengths of this composite and the neat EPN were determined as 95.7 +/- 6.92 and 96.6 +/- 4.77 MPa, respectively. The T-50 temperatures of the BA- and AH-doped composites were higher than that of neat EPN. The highest char percentages were observed in the triple composites, while the lowest were observed in the EPN/CtW composites. The combustion of the triple composite with a CtW:BA:AH ratio of 20:5:10 wt% was spontaneously extinguished in 37 s. Horizontal flammability testing also showed better fire resistance for the CtW/BA/AH composites over their CtW counterparts, with the highest estimated limiting oxygen index of 32.3 obtained for the 20:5:10 wt% composite. The water sorption test results show that the CtW composites had the highest hydrophilicity, especially those with 30 wt% CtW or higher, in the presence of water at room temperature.
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, Gülnare
Aloe 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.
Citation - WoS: 7
Citation - Scopus: 8
Methylene Blue Sorption Performance of Lignocellulosic Peach Kernel Shells Modified With Cellulose Derivative Chitosan as a New Bioadsorbent
(Elsevier, 2024) Soydal, Ülkü; Kocaman, Suheyla; Ahmetli, Gulnare; Avsar, Semra
In this study, adsorption isotherms (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) and thermodynamic properties of cationic methylene blue (MB) dye adsorption onto chitosan-coated peach kernel shell waste (CTS-PKSh) from wastewater were investigated. CTS was cross-linked with citric acid (CA) and glutaraldehyde (GA). The adsorbents were characterized by FE-SEM/EDS, FTIR, and particle size distribution. MB adsorption behavior onto the biosorbents was investigated concerning parameters such as adsorbent dosage (0.8-8 g/L), time (0-540 min), pH (3-10), initial dye concentration (50-700 mg/L), and temperature (25-55 degrees C). The Langmiur q(max) and experimentally q(e) MB adsorption capacities of the new adsorbents were found to be 227.27 and 201 mg/g for CA cross-linked CTS-PKSh (CA@CTS-PKSh) and 111.12 and 96.5 mg/g for GA cross-linked CTS-PKSh (GA@CTS-PKSh), respectively. The results of thermodynamic analysis showed that adsorption was feasible, exothermic, and spontaneous. According to adsorption and recyclability results, CA@CTS-PKSh was more effective for MB removal at a 2 g/L adsorbent dose for an initial dye concentration of 100 mg/L, 25 +/- 1 degrees C, contact time 60 min, and pH 7.
New Antibacterial Biocomposite Films and Evaluation of Their Properties
(IKSAD Publications, 2022) Soydal, Ülkü; Söylemez Günbattı, Fadim; Ahmetli, Gülnare
The rapid consumption of synthetic polymers and their products, as well as the widespread use of plastic waste, has become one of the major environmental problems. The use of bio-based polymers is increasing to reduce the use of petroleum-based plastics due to their negative effects on the environment. However, the use of biodegradable polymers is limited for reasons such as performance (such as brittleness, poor barrier properties), processing (such as low thermal withstand temperatures), and cost. The application of nanotechnology to polymers provides new advantages in both improving the properties of these materials and reducing their costs. In addition, technological developments have increased the quality standards of people and, in parallel, increased expectations about cleaning. Therefore, in recent years, the interest in the production and application of environmentally friendly and natural plant-based antibacterial materials has been increasing day by day. Research on the use of supplements such as nanoclay, different polymer combinations, antioxidant/antibacterial additives to improve or change the properties of biobased composite films has become more widespread. In this study, to produce fully renewable and biodegradable composite films; Bio-based acrylated epoxidized soybean oil (AESO) and two different reinforcement materials were used as polymeric matrix. First of all, the antibacterial properties of the films formed by adding thyme oil, a strong essential oil with proven antibacterial properties, to the matrix at different rates (0%, 1%, 2%, 3%, 4%, 5% by weight) were examined and the most appropriate ratio was determined. By keeping this ratio constant, nanocomposite films were prepared by adding different ratios of nanoclay (1%, 2%, 3%, 4%, 5% by weight) in the second stage of the study. The antibacterial activity tests of the obtained materials were carried out, and the effect of the reinforcement ratio on the pH, swelling-solubility-water content and thermal properties were investigated. In addition, the prepared films were characterized with FT-IR spectra to determine possible interactions of functional groups.
Phenolic Epoxy Resin/Cotton Waste Biocomposites Preparation and Characterization
(IKSAD Publications, 2021) Soydal, Ülkü; Kocaman, Süheyla; Ahmetli, Gülnare
In recent years, the increasing interest in the use of waste natural fillers in composites is due to desirable properties such as biodegradability, renewability, low density, environmental friendliness, and cost-effectiveness (Saba, Jawaid, Paridah, Al-othman, 2016). Cotton waste consisting of cotton stems, leaves, and husks, has a high cellulose content. Phenol novolac epoxy resins are multifunctional epoxy resins manufactured from phenol novolac resin and epichlorohydrin. When cured, they form cured materials that possess a mesh structure with a high cross-linking density. They also demonstrate excellent performance in heat and chemical resistance and are used in composite materials, resists, and laminates (Kocaman, 2020). In this study, cotton waste (CtW) was utilized firstly as raw waste filler material in phenolic novolac-type epoxy (EPN) resin to preparation of biocomposites. For characterization of biocomposites, scanning electron microscopy (SEM) analysis, tensile, hardness and water sorption tests were performed. The effect of the CtW dose on the mechanical, and water sorption properties of the composites were investigated. The tensile strength of the neat EPN was determined to be 96.64.77 MPa, while the composite with the appropriate amount of filler 20% by weight had a tensile strength of 95.66.20 MPa. CtW filler increased the water uptake percentage of the EPN matrix (0.85%) and it was determined as 3.39% at 20 wt% CtW during 30 day. Epoxies can absorb 0.1-5% water depending on its formulation and type (Licari, 2003). However, this trend and the slight decrease in mechanical properties are not critical obstacles for the use of CtW in the manufacture of inexpensive epoxy- and bio-based eco-friendly products.
Citation - WoS: 15
Citation - Scopus: 18
Polystyrene Waste-Modified Epoxy/Nanoclay and Hybrid Composite Coatings
(Wiley, 2023) Özmeral, Nimet; Kocaman, Süheyla; Soydal, Ülkü; Ahmetli, Gülnare
In this study, phenolic novolac-type epoxy (EPN) resin was modified with 4 wt% thermoplastic polystyrene (PS) waste and was used as the polymer matrix for the first time. Two types of composites were prepared: (i) nanocomposites with 1-3 wt% nanoclay (NC) and (ii) hybrid composites. Pristine (NC) and tetramethylammonium chloride modified nanoclays (MNC) were used at a 2 wt% ratio in hybrid composites with 25-35 wt% red mud waste (RMW). The corrosion protection properties of the coatings were determined by immersion test in 5 wt% NaOH, HCl, and NaCl solutions. The water sorption of hybrid composites varied between 1%-3.6% and 1%-5.3%, while it was between 0.82% and 1.02% in EPN-PS/NC nanocomposites. The weight gain percentage values of hybrid composites in corrosive media for the base and salt solutions were determined much lower (0.59%-0.75% and 0.46%-0.59%, respectively) than water sorption. Surface morphologies of hybrid composites were examined by scanning electron microscopy before and after corrosion tests. MNC-30 wt% RMW hybrid composite was found more suitable due to high corrosion resistance in basic and salty environments, storage modulus, loss modulus, and glass transition temperature (T-g) values (90.6 & DEG;C) as compared with NC-30 wt% RMW hybrid composite.
Citation - WoS: 13
Citation - Scopus: 14
Red Mud Waste/Nanoclay Epoxy Hybrid Composites: Mechanical, Thermal, and Flammability Properties
(Wiley, 2023) Özmeral, Nimet; Soydal, Ülkü; Kocaman, Süheyla; Ahmetli, Gülnare
In this study, bisphenol A-type epoxy (ER) and epoxy phenol novolac resins (EPN) with two amine-type curing agents (KH 816 and IPOX EH 2041) having different total amine values were selected. The mechanical properties and density of the EPN resin were found higher in the case of both curing agents. EPN was modified with polystyrene (EPN-PS) and used as a matrix using an IPOX hardener. Nano- and hybrid composites were prepared with pristine and modified with tetramethylammonium chloride nano montmorillonite (NC and MNC), and red mud waste (RMW). The chemical structure was elucidated by the Fourier transform infrared (FT-IR). The composites were characterized by scanning electron microscopy and x-ray diffraction. Appropriate PS and NC ratio was accepted as 4% and 2% by weight, respectively. Curing degrees calculated from the FT-IR spectra of ER, EPN, and EPN-PS were 99.3%, 99.9%, and 86.5%, respectively. A comparative study of the two binary systems; (i) 2 wt% NC-(15-35) wt% RMW; and (ii) 2 wt% of MNC-(15-35) wt% of RMW on the mechanical, thermal, and flammability properties of EPN-PS matrix was carried out. The appropriate RMW ratio was 30 wt%. Hybrid composites with 25-30 wt% RMW can be considered self-extinguishing materials.
Sour Cherry Kernel Reinforced Biocomposite Films and Investigation of Some Properties
(Selcuk University Faculty of Technology, 2021) Soydal, Ülkü; Yıldırım, Murat; Bul, Muhammed Melih; Ahmetli, Gülnare
Most of the polymers and polymer composites produced in the industrial field are of petroleum origin.The fact that these depleting petroleum-based resources are both expensive and bring environmental problems such as climate change and waste problems lead scientists to search for cheaper and renewable resources instead of petroleum-based resources. Therefore, in recent years, many research groups have been working on the synthesis of bio-based polymeric composites from different renewable resources such as oil-based resources [1][2]. On the other hand, evaluating waste and by-products in the food industry is an increasingly important issue today. The reason for this is that a large amount of solid and liquid waste materials are formed during the production, processing and consumption stages of foods. Especially since the wastes of the fruit and vegetable industry contain a high amount of water, microbial deteriorations that occur when they are thrown into the nature or toxic substances that occur during their disposal create environmental pollution[3]. For this purpose, in this study, sour cherry kernel (SCK), which is generated as waste from the fruit juice industry, was used as a filler for the preparation of composite film materials in biobased acrylated epoxidized soybean oil (AESO) resin matrix. Composite films were formed by adding different ratios of sour cherry kernel powder (0%, 10%, 20%, 30%, 40%, 50% by weight). and, the antibacterial, pH, swelling-solubility-water content and mechanical properties of the film composites were investigated. It was observed that the obtained SCK/AESO composite films were antibacterially effective against Gram-positive Staphylococcus aureus and Enterococcus faecalis) and Gram-negative (Escherichia coli and Klebsiella pneumoniae) bacterias.
Citation - Scopus: 23
Water Sorption, Thermal, and Fire Resistance Properties of Natural Shell-Based Epoxy Composites
(John Wiley and Sons Inc, 2022) Zamani, Kianoosh; Kocaman, Süheyla; Işık, Murat; Soydal, Ülkü; Özmeral, Nimet; Ahmetli, Gülnare
In this study, walnut shell (WSh), hazelnut shell (HSh), and mussel shell (MSh) waste as inexpensive reinforcements were recycled for the preparation of epoxy composite materials. Subsequent used inexpensive fillers are chars (WShC and HShC), which are the pyrolysis solid products of the natural WSh and HSh wastes. Three types of epoxy resins: bisphenol-A type (DGEBA), modified with polyurethane (MER with PU), and rubber modified (MER with rubber) epoxy resins were used as the matrix in MSh composites. Thermogravimetric analysis of the composites showed that the thermal strength of the epoxy matrix increased significantly with the MSh and chars. The best water sorption results were obtained with the MSh. The contact angle values of MSh composites prepared with DGEBA epoxy resin were quite high (111°–113.5°) and their water retention values ranged from 0.2% to 0.32%. The composites that were produced using 50 wt% chars and the same epoxy resin showed better flammability stability. The full extinction times were determined as 63 and 58 s for WShC and HShC composites, respectively. © 2022 Wiley Periodicals LLC.