Browsing by Author "Soydal, Ulku"

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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: 1
Citation - Scopus: 1
Synthesis of Epoxy Resin From Linseed Oil and Development of New Bio-Based Films Using Calendula Officinalis L. Oil
(Elsevier, 2025) Soydal, Ulku; Ahmetli, Gulnare; Orac, Aysun; Telli, Osman Berat
Epoxy resin thin films are widely used in applications such as anticorrosive coating materials, insulating and electronic packaging films, and adhesives; accordingly, research on new epoxy materials has become increasingly important. Developing new bio-based epoxy films or coatings is important to address this issue. This study synthesized epoxidized linseed oil (ELO) by epoxidation of linseed oil, and a novel bio-based matrix was formed with commercial epoxy resin (ER) at a weight ratio of 3:2. The characterization of ELO was performed using Fourier Transform Infrared Spectroscopy (FTIR), as well as by determining the iodine and epoxide groups. In addition, new films were formed by adding 1 %, 3 %, 5 %, 7 %, 10 %, and 15 % by weight Calendula officinalis L. oil (CldO). The effect of CldO on mechanical (thickness, tensile strength, and elongation at break), structural (Scanning Electron Microscopy (SEM) and FTIR), water barrier (WVP, water solubility, swelling), chemical resistance, antibacterial, and biodegradation properties was evaluated. ELO and CldO reduced the film's thickness. The film's water vapor permeability ratio (WVTR) was relatively low, ranging from 0.0153 g/(m2 center dot d) to 0.0661 g/(m2 center dot d). A 10 wt% CldO was selected as an appropriate ratio, especially regarding mechanical properties, water vapor permeability rate (WVPR), and opacity. Above 10 wt% CldO, tensile elongation sharply decreased, while water solubility and opacity significantly increased. Films containing CldO at 10 wt% and 15 wt % demonstrated enhanced antibacterial properties against certain pathogenic bacteria and biodegradation. In addition, all films showed resistance to 5 % NaCl, 3 % HCl, and 50 % ethanol solutions.