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Öğe A Novel Route to Glass Fiber-Reinforced Epoxy Matrix Composites: Visible Light Activated Radical Induced Cationic Frontal Polymerization(Wiley-V C H Verlag Gmbh, 2025) Kurtulus, Cenk; Ciftci, Mustafa; Tasdelen, Mehmet AtillaIn the current study, a novel radical-induced cationic frontal polymerization (RICFP) concept capable of rapid curing at room temperature via visible light irradiation is represented. Initially, the optimal formulation, which can be most effectively cured with visible light irradiation, is determined based on thickness, hardness, curing speed, and mechanical properties using FT-IR, DSC, TGA, and flexural test methods. Subsequently, the viability of the method is illustrated by fabricating glass fiber-reinforced composites through the hand lay-up technique, employing the optimized formulation and glass fibers in various forms (chopped strand mat and biaxial). Mechanical properties of the obtained composites, including bending, tensile, and shear tests, are carried out according to relevant international standards and compared with reference composites thermally cured with amine-based hardener by conventional method. A novel visible light curable epoxy resin for glass fiber-reinforced composites is developed, combining industrial-grade epoxy resin with a photoinitiator, photosensitizer, reactive solvent, and thermal initiator. Optimal formulation is identified by evaluating thickness, hardness, curing speed, and mechanical properties. The composites produced show mechanical properties comparable to thermally cured ones. imageÖğe Grafting of POSS Hybrid Nanoparticles onto Poly(Vinyl Chloride) via Diels-Alder Click Reaction(Wiley-V C H Verlag Gmbh, 2025) Ozdogan Tasci, Reyhan; Tasdelen, Mehmet AtillaIn this study, commercially available PVC was successfully modified with POSS hybrid nanoparticles at various molar ratios via catalyst-free Diels-Alder (DA) click chemistry, achieved by simple heating at approximately 80 degrees C. Furan and maleimide clickable groups were independently attached to PVC and aminopropyl isobutyl POSS through nucleophilic substitution reactions. However, furan functionalization of Poly(vinyl chloride) (PVC) led to partial chain scission and HCl elimination, confirmed by gel permeation chromatography (GPC) analysis, resulting in reduced molecular weight and mechanical properties. The furan functionalization degree was 3.67% (H-1-NMR) and 3.98% (elemental analysis). Among the modified samples, only PVC-g-POSS-1:0.25 (PVC:POSS molar ratio) was soluble in DMSO-d(6), with a grafting degree of 3.78% and DA reaction efficiency of 97.08%. Chemical grafting improved thermal and mechanical properties significantly. The glass transition temperature increased from 60.4 degrees C (neat PVC) to 84.1 degrees C, and the 50% degradation onset rose from 254.02 degrees C to 362.11 degrees C. Mechanical testing showed enhanced performance (yield stress: 14.2 MPa; elongation: 69.4%; elastic modulus: 300.6 MPa), outperforming physically mixed controls. SEM and TEM analyses showed that the best polyhedral oligomeric silsesquioxanes (POSS) dispersion occurred in PVC-g-POSS-1:0.25, with a relatively uniform distribution. As the POSS content increased in PVC-g-POSS-1:0.5, larger aggregates (>200 nm) formed, indicating stronger nanoparticle interactions and reduced dispersion.Öğe Improving the mechanical properties of fiber-reinforced polymer composites through nanocellulose-modified epoxy matrix(Budapest Univ Technol & Econ, 2024) Kuyumcu, Mustafa; Kurtulus, Cenk; Ciftci, Mustafa; Tasdelen, Mehmet AtillaIn this study, the potential use of nanocrystalline cellulose (CNC) modified epoxy nanocomposite as a matrix is investigated for both glass and carbon fiber-reinforced composites. Various amounts of CNCs (1, 2, 4, and 6 wt%) were added to bisphenol A diglycidyl ether-based epoxy resin (DGEBA), and the optimum CNC loading was determined as 4 wt% in terms of mechanical and thermal properties. Compared to the reference sample containing a neat epoxy matrix with the obtained carbon fiber/CNC-epoxy (CNC/epoxy/CF) and glass fiber/CNC-epoxy (CNC/epoxy/GF) hybrid nanocomposites, significant improvements have been determined in the in-plane shear modulus and strength, and flexural modulus, respectively. The mechanical properties improvements of CNC/epoxy/CF hybrid composites are approximately 0.9% higher than the CNC/epoxy/GF hybrid composites. Additionally, the distribution of CNC in hybrid nanocomposites is also investigated by scanning and transmission electron microscopies. It is noted that the homogenous dispersion of CNCs in the epoxy matrix and their diameters varied from 10 to 100 nm are detected at higher magnification.Öğe In-situ preparation of halloysite nanotube-epoxy thermoset nanocomposites via light-induced cationic polymerization(Elsevier Ltd, 2021) Bekin Acar, Seda; Çiftci, Mustafa; Bouharras, Fatima Ezzahra; Raihane, Mustapha; Tasdelen, Mehmet AtillaIn the present study, homogeneous mixtures of halloysite nanotubes (HNTs)-epoxy nanocomposites are prepared through chemical treatments. Naturally present halloysite nanotubes (HNT) are primarily modified by 3-(glycidyloxypropyl)trimethoxysilane and subsequently utilized as nanofillers in a mixture of bisphenol A diglycidyl ether and trimethylolpropane triglycidyl ether by varying weight % of modified HNT from 0 to 8%. Photoinitiated cationic crosslinking polymerization of this mixture facilitates the in-situ preparation of HNT/thermoset nanocomposites at room temperature. The covalent attachment of HNT in the thermoset matrix has been confirmed by monitoring the characteristic signals of the mixture, nanofiller, neat thermoset, and final nanocomposite using fourier transformed infrared (FT-IR) spectroscopy. Furthermore, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses proved the existence and distribution of HNT in the thermoset nanocomposites. Indeed, a combination of agglomerated/non-agglomerated HNTs in the thermoset matrix is also determined. On the other hand, mechanical properties of nanocomposites are significantly improved with increase in HNT loading up to 4% ratio. Adding 4% of modified HNT into epoxy increased its tensile strength and elasticity modulus by 6.9 times and 2.3 times than the corresponding neat epoxy thermoset, respectively, without scarifying thermal stability. Therefore, the HNT/epoxy thermoset nanocomposites are suitable candidates for various applications as an alternative of expensive carbon nanotube containing analogues.Öğe Orthogonal synthesis and modification of hyperbranched polymers via different colors of light(Wiley, 2024) Kokcu, Esra; Ciftci, Mustafa; Tasdelen, Mehmet AtillaA versatile and straightforward approach for the synthesis of functional hyperbranched polymers with tunable properties is represented utilizing a chromatic orthogonal protocol. The method involves the combination of photo-induced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) and self-condensing vinyl polymerization (SCVP) under visible light irradiation leading to the formation of hyperbranched polymers with well-defined properties possessing photo-caged diene moieties. Upon UV light irradiation, the remaining photoenol functionality was efficiently activated for the post-functionalization of the synthesized hyperbranched polymers with maleimide functional molecules via Diels-Alder photo-click chemistry. Both low molar mass and polymeric maleimide functional click components, namely N-phenylmaleimide, poly(ethylene glycol)-maleimide and polycaprolactone-maleimide were quantitively attached onto the hyperbranched polymers under ambient conditions. The results obtained from our protocol indicate high efficiency and convenience, offering a straightforward strategy for the design and synthesis of functionalized hyperbranched polymers. The chromatic orthogonal nature of the protocol enables precise control over the modification process, adding versatility to the materials obtained. Overall, this research lays the groundwork for novel pathways in material design, opening new possibilities for advanced materials with tailored properties. imageÖğe Photon-powered composite fabrication: Advancing fiber-reinforced composites with light-induced systems(Pergamon-Elsevier Science Ltd, 2025) Ciftci, Mustafa; Tasdelen, Mehmet AtillaFiber-reinforced composites (FRCs) are advanced materials combining fibers (e.g., glass, carbon, aramid) with a polymer matrix to provide high strength, stiffness, durability, and lightweight properties. Traditional FRC manufacturing methods rely on thermal curing, which involves high energy consumption (often exceeding 100 degrees C for several hours) and long processing times, increasing production costs and limiting sustainability. To address these limitations, light-induced polymerization has emerged as a promising alternative. Light-induced polymerization, a process in which monomers are transformed into polymers through photoinitiators, offers spatial and temporal control, significantly reducing curing times to minutes while minimizing energy consumption. Unlike thermal curing, this method enables precise polymerization using various wavelengths of light, from UV to visible range, while reducing the need for toxic chemicals or solvents. Studies have demonstrated that UV-cured FRCs can achieve mechanical properties comparable to thermally cured composites, depending on the fiber content and resin formulation. Recent advancements, such as stepwise UV curing and radical-induced cationic frontal polymerization (RICFP), have improved light penetration, enabling uniform polymerization even in thick laminates (up to 20 mm). However, challenges such as limited light penetration due to fiber absorption and optical interference remain key barriers to widespread adoption. This review uniquely consolidates recent advancements in light-induced polymerization for FRC fabrication and critically evaluates strategies to overcome these challenges, including photoinitiator selection, diluent optimization, and wavelength tuning. By systematically discussing the role of photoinitiators, fiber types, fillers, and irradiation wavelengths, this work provides novel insights into the chemistry, processing strategies, and future directions of this emerging technology.Öğe Polyester/clay nanocomposite synthesis via metal-free azide-alkyne click reaction(Taylor & Francis Inc, 2025) Ozdogan Tasci, Reyhan; Daglar, Ozgun; Durmaz, Hakan; Tasdelen, Mehmet AtillaA polyester/montmorillonite (MMT) nanocomposite is synthesized via metal-free azide-alkyne 1,3-dipolar cycloaddition (metal-free AAC) click reaction. An aliphatic polyester, poly(1,4-butane diol acetylene dicarboxylate), bearing electron-deficient alkyne groups and an azide-functionalized montmorillonite were prepared following literature procedures, then coupled at room temperature for 24 h at varied clay loadings (1, 5, and 10 wt.%) to yield the nanocomposites. Structural, thermal and morphological features of the nanocomposites are evaluated with various characterization techniques. Under nitrogen atmosphere, all nanocomposites showed enhanced thermal stability with one-step degradation, and the char yield increased by similar to 30% at the highest clay loading relative to the neat polyester. DSC revealed higher transition temperatures, with melting temperature up by similar to 3% and crystallization temperature up by similar to 11% at maximum loading, consistent with nucleation by silicate platelets. TEM and XRD evidenced mixed exfoliated and intercalated morphologies. Overall, the metal-free AAC click approach affords well-dispersed, thermally reinforced polyester/clay nanocomposites under mild, catalyst-free conditions.Öğe POSS-based hybrid nanocomposites(Elsevier, 2021) Bekin Acar, Seda; Özdoğan, Reyhan; Tasdelen, Mehmet AtillaHybrid nanocomposites have attracted considerable attention since they could combine superior advantages of two or more nano-fillers. Owing to the multifunctional properties of nano-fillers, they have emerged as a promising new class of materials for high-tech applications. Various nano-fillers including clay, carbon nanotubes, graphene, metal oxides, and polyoctahedral oligomeric silsesquioxane (POSS) have been extensively used for the preparation of hybrid nanocomposites. Among them, POSS derivatives have received significant attention due to their precisely defined hybrid structures with a variety of functional groups helping to chemically or physically combine with other nano-fillers to enhance stiffness performance and reduce the electrical conductivity of the material. In this chapter, hybrid nanocomposites prepared by POSS with other one-dimensional nano-clays, two-dimensional graphene and graphene oxides, carbon nanotubes and boron nitrides, and three-dimensional fullerenes, gold, silver, and iron nanoparticles, and titanium and silicon dioxides are explored in detail.Öğe Preparation and mechanical characterization of halloysite containing styrene-butadiene rubber nanocomposites(İdris Karagöz, 2023) Açar, Seda Bekin; Tasdelen, Mehmet Atilla; Karaağaç, BağdagülIn this study, different SBR nanocomposites were prepared by adding pure halloysite (HNT) and thiol- and vinyl- modified HNT nanofillers to styrene-butadiene rubber (SBR) compounds at 3 phr. These nanocomposites were characterized in terms of rheological, mechanical, and morphological properties. The aging process and crosslinking density of the prepared nanocomposites were also investigated in the presence of HNT nanotubes. The sulfur curing characteristics of SBR vulcanizates were determined by moving die rheometer. It was found that the SBR nanocomposite including thiol- modified HNT had higher crosslinking density than the other nanocomposites prepared with pure HNT and vinyl- modified HNT. Also, all SBR nanocomposites containing pure and functionalized HNT showed better mechanical properties compared to the reference sample without nanofillers. This result showed the reinforcement effect of HNT in the SBR matrix. In addition, the crosslink density and mechanical strength of SBR/HNT nanocomposites increased with thermal aging process. This confirmed the post-cure effect.Öğe Visible light-induced synthesis of polysulfone-based graft copolymers by a grafting from approach(Wiley, 2020) Çiftçi, Mustafa; Tasdelen, Mehmet AtillaThe synthesis of polysulfone (PSU) graft copolymers by a two-step "grafting from" approach is described. First, a chlorofunctional PSU (PSU-Cl) is formed via chloromethylation of a commercial PSU. The formed polymers are used macroinitiator for the dimanganese decacarbonyl assisted free-radical polymerization of tert-butyl acrylate, methyl methacrylate, and styrene to give the desired graft copolymers. Moreover, amphiphilic graft copolymers are also formed via posthydrolyzation of poly(tert-butyl acrylate) containing graft copolymers. The intermediates at various stages and the ultimate graft copolymers are characterized by various analysis techniques. (c) 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 412-416
