Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleAçık Erişim2026Scopus SJRQ2Sustainable epoxy based biocomposites reinforced with Melilotus officinalis: Structural, mechanical, thermal, and dielectric performance evaluation
Solmaz, Adnan; Açar, Mikail; Demirel, Maruf Hurşit; Deniz, Şermin; Aydoğmuş, Ercan
The aim of this study is to investigate the manufacturability of Melilotus officinalis (L.) reinforced epoxy biocomposites as a renewable biofiller and to characterize the mechanical, thermal, and dielectric properties of these materials. For this purpose, composites containing biomass at 0, 3, 6, and 9 wt.% were prepared; the samples were examined by tensile testing, FTIR, SEM, EDX, XRD, Shore D hardness, thermal conductivity, and dielectric analysis. The findings showed that with increasing M. officinalis content, tensile strength, hardness, and density decreased, while ductility and elongation at break improved. The significant decrease in thermal conductivity revealed an increase in heat insulation efficiency. Dielectric analyses showed that strong interfacial polarization occurred at low frequencies, and the dielectric constant and loss values decreased as the frequency increased. SEM examinations confirmed that the plant-derived filler was homogeneously distributed and formed acceptable interfacial adhesion with the matrix. In conclusion, although the use of synthetic epoxy matrix and the decrease in mechanical strength limit load-bearing structural applications, M. officinalis is a promising biofiller for lightweight and partially bio-based epoxy composites thanks to its increased ductility and improved thermal insulation properties. © The Author(s) 2026. This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage).
- MakaleAçık Erişim2026Scopus SJRQ1Comparative Study of Enzymatic and Oxidative Polymerization of a Benzothiazole-Based Schiff Base and Its Antibacterial Properties
Kaya, İsmet; Solmaz, Adnan; Abuawad, Mohammed Majed Shible
In this study, the Schiff base 1-(((6-nitrobenzo[d]thiazol-2-yl) imino)methyl)naphthalen-2-ol (NBTIMN) was synthesized and subsequently polymerized by two different methods. Oxidative polymerization in the presence of organic (o-(NBTIMN)-O) and aqueous alkaline media (o-(NBTIMN)-A) was one of the techniques. The other was enzyme-catalyzed oxidative polymerization (o-(NBTIMN)-E), which was conducted at room temperature with hydrogen peroxide and the enzyme horse radish peroxidase (HRP). The structures of the obtained oligomers were characterized using FT-IR, 1H-13C-NMR, UV–Vis, CV, and GPC analyses, and their electrochemical and optical band gaps were determined as 2.68, 2.66, and 2.49 eV, and 3.08, 2.90, and 3.07 eV for o-(NBTIMN)-O, o-(NBTIMN)-A, and o-(NBTIMN)-E, respectively. Thermal analyses demonstrated that the o-(NBTIMN)-O and o-(NBTIMN)-A derivatives exhibited enhanced thermal stability, characterized by higher decomposition temperatures and LOI values. SEM analyses revealed distinct differences in surface morphologies depending on the polymerization conditions. Antibacterial assays showed that o-(NBTIMN)-O exhibited the strongest broad-spectrum inhibition, whereas NBTIMN displayed pronounced activity against S. aureus. In contrast, o-(NBTIMN)-A and o-(NBTIMN)-E were found to be inactive. These results highlight the critical influence of polymerization conditions on both the physicochemical characteristics and the biological activities of the synthesized structures. Importantly, the comparative design of enzymatic and chemical polymerization demonstrates the potential for environmentally friendly synthesis strategies. The distinct electrochemical and thermal properties suggest applicability in electronics and sensor-related fields, while the pronounced antibacterial activity of o-(NBTIMN)-O holds promise for biomedical and antimicrobial applications.
- MakaleAçık Erişim2026Scopus SJRQ2Oxidative polycondensation of phenylhydrazine-based Schiff base: structural, thermal, optical and dielectric investigations
Kaya, İsmet; Bayır, Erdal; Solmaz, Adnan
In this study, the Schiff base 3-((2-phenylhydrazono)methyl)benzene-1,2-diol (3-PHMB) was synthesized through a condensation reaction between 2,3-dihydroxybenzaldehyde (2,3-DHBA) and phenylhydrazine (PH). The obtained Schiff base was subsequently subjected to oxidative polymerization in a 10% KOH (w/v) aqueous medium using hydrogen peroxide (35% H₂O₂), sodium hypochlorite (6–14% NaOCl), and oxygen (O₂) as oxidants, yielding the oligomers o-(3-PHMB)-P, o-(3-PHMB)-H, and o-(3-PHMB)-O. The structural, morphological, thermal, optical, and electrochemical characteristics of the synthesized compounds were comprehensively investigated using FT-IR, NMR, SEM, TG-DTA, UV-Vis, CV, and GPC techniques. UV-Vis and CV analyses revealed that the optical band gaps (Eg) were 2.33 eV for 3-PHMB, 2.06 eV for o-(3-PHMB)-P, 2.16 eV for o-(3-PHMB)-H, and 2.02 eV for o-(3-PHMB)-O, while the electrochemical band gaps (Eg′) were calculated as 2.03 eV, 1.65 eV, 1.63 eV, and 1.50 eV, respectively. Thermal analysis showed that the char yields at 1000 °C were 41.43% for o-(3-PHMB)-P, 38.72% for o-(3-PHMB)-H, and 44.35% for o-(3-PHMB)-O. Dielectric measurements indicated that o-(3-PHMB)-O exhibited higher polarization capacity and energy storage ability compared to the other oligomers. Moreover, the electrical conductivity values increased steadily with frequency; at 100 kHz, the conductivity was recorded as 1.74 × 10⁻⁵ S cm⁻¹ for o-(3-PHMB)-O and 1.64 × 10⁻⁵ S cm⁻¹ for o-(3-PHMB)-P. These findings demonstrate that the synthesized Schiff base oligomers are promising candidates for dielectric and optoelectronic applications due to their high thermal stability, controlled molecular weight distribution, and semiconducting properties.
- MakaleYalnız künye2026Scopus SJRQ1Oxidative Polycondensation of Pyrazolone-Based Schiff Bases: Synthesis, Structural Characterization, Thermal and Electrical Properties
Solmaz, Adnan; Çakmak, Reşit; Kaya, İsmet
Schiff base derivatives, namely 3-(((2-hydroxynaphthalen-1-yl)methylene)amino)-1-phenyl-1-pyrazole-5-one (3-APPHNA) and 4-(((2-hydroxynaphthalen-1-yl)methylene)amino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3-one (4-APPHNA), were synthesized via the condensation reaction of 3-amino-1-phenyl-2-pyrazolin-5-one (3-APP) and 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one, (4-APP) with 2-hydroxynaphthaldehyde (2-HNA) in ethanol. Synthesized monomers were then converted into their oligomeric derivatives via oxidative polycondensation carried out using NaOCl. The structural, thermal, optical, electrochemical, and morphological properties of the obtained monomers were comprehensively characterized using fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H-NMR), carbon-13 nuclear magnetic resonance (13C-NMR), ultraviolet-visible spectrophotometer (UV–vis), thermogravimetry-derivative thermogravimetry (TG-DTG), and cyclic voltammetric analyses. Spectroscopic studies confirmed the successful synthesis of Schiff bases and the presence of stable azomethine bonds. Molecular weight, glass transition temperature, and surface morphologies of oligomers were determined by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and field emission scanning electron microscope (FE-SEM) measurements, respectively. The Mn values of oligo(3-APPHNA) and oligo(4-APPHNA) were found to be 3400 and 2900 Da, respectively. The results revealed an oxidative oligomerization process yielding relatively narrow molecular weight distributions. Oligo(4-APPHNA) has shown more pronounced semiconductor properties compared to other oligomers, considering its 2.30 eV optical band gap and frequency-dependent electrical behavior. Additionally, dielectric measurements showed that oligo(4-APPHNA) exhibited higher dielectric constant, dielectric loss, and AC conductivity values throughout the investigated frequency range. These findings suggest that the synthesized oligomers are promising candidate materials for future optoelectronic and semiconductor applications, but further research at the device level is needed.
- MakaleAçık Erişim2025Scopus SJRQ2Synthesis and characterization of oligomers contain phenylhydrazyne unit via oxidative polycondensation: Adsorption studies, kinetic modeling and validation methods
Bayır, Erdal; Solmaz, Adnan; Kaya, İsmet; Yağmur, Hatice Karaer
In this study, 4-((2-phenylhydrazono)methyl)benzene-1,2-diol (4-PHBD) Schiff base was obtained from the condensation reaction between 3,4-dihydroxybenzaldehyde (3,4-DHBA) and phenylhydrazine (PH). The obtained Schiff base (4-PHBD) was polymerized using H2O2, NaOCl, and O2 oxidants in an aqueous basic medium (10 % KOH) and 4-PHBD was converted to o-(4-PHBD)-P (by H2O2 oxidant), o-(4-PHBD)-H (by NaOCl oxidant) and o-(4-PHBD)-O (by O2 oxidant). The structures of Schiff base and oligomers were characterized with FT-IR, NMR, SEM, TGA, UV-Vis, CV and GPC measurements. The Cyclic Voltammetry and UV-Vis measurements were used to ascertain the compounds' optical (Eg) and electrochemical (Eg’) band gaps, respectively. The Eg values of o-(4-PHBD)-P, o-(4-PHBD)-O and o-(4-PHBD)-H were found be 2.99, 2.63 and 3.26 eV, respectively. o-(4-PHBD)-O was used as an adsorbent in the removal of methylene green (MG) from an aqueous solution. The obtained data were applied to pseudo-first order and pseudo-second order kinetic models. It was determined that the adsorption process obeyed the pseudo first order kinetic model. The kinetic model was validated with R2, RMSE, SSE, SD, Δqe (%), MSE and ARE validation methods. The activation energy (Ea) was calculated as 7.31 kJ mol−1 using the Arrhenius equation. It was determined that the adsorption of MG on o-(4-PHBD)-O was physical adsorption.
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İncele - MakaleAçık Erişim2025Scopus SJRQ2High thermal stability and dielectric performance of phenylhydrazine-based Schiff base oligomers obtained via oxidative polycondensation
Solmaz, Adnan; Kaya, İsmet; Bayır, Erdal
In this study, the 2-PHMBD Schiff base, synthesized through the condensation of 2,4-dihydroxybenzaldehyde (2,4-DHBA) with phenylhydrazine (PH), was subjected to oxidative polymerization in a basic medium using hydrogen peroxide (H2O2), sodium hypochlorite (NaOCl), and molecular oxygen (O2) as oxidizing agents. Three oligomers, designated as o-(2-PHMBD)-P, o-(2-PHMBD)-H, and o-(2-PHMBD)-O, were successfully obtained and comprehensively characterized by FT-IR, 1H-13C-NMR, UV–Vis, CV, GPC, SEM, TGA, and DSC analyses. Spectroscopic results confirmed the successful polymerization, while morphological and thermal analyses revealed the distinct physical characteristics of the oligomers. According to GPC data, o-(2-PHMBD)-H exhibited the highest average molecular weight of 4700 Da, and TGA analysis demonstrated that o-(2-PHMBD)-O had the highest thermal stability with a residue of 46% at 1000 °C. The DSC results showed the highest glass transition temperature of 132 °C for o-(2-PHMBD)-H. UV–Vis and CV measurements indicated reduced optical and electrochemical band gaps compared with the monomer, with the lowest optical band gap determined as 2.74 eV. Dielectric measurements revealed that o-(2-PHMBD)-H displayed the highest dielectric constant of 2.57 and conductivity of 2.49 × 10⁻7 S cm⁻1. These results demonstrate that phenylhydrazine-based Schiff base oligomers possess high thermal stability and favorable dielectric properties, making them promising materials for optoelectronic and dielectric device applications.
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