In carbon-fiber-reinforced composites, hydroxyl and carboxyl groups are formed on the carbon fiber surface as a result of the oxidation process applied to the fibers. These groups strengthen the interfacial bond between the fibers and the epoxy resin. In addition, the silanization process chemically bonds amino and glycidyl groups to the fiber surface, further improving adhesion and thus optimizing the performance of the joint. In light of this, the primary objective of the present study is to optimize the performance of adhesive joints by applying oxidation and silane modifications to the fibers added to the adhesive and the bonded metal materials. In this study, carbon fibers underwent oxidation treatment for 5, 10, and 20 min, followed by silanization with 3-aminopropyltriethoxysilane (APTES) and glycidoxypropyltrimethoxysilane (GPTMS) silane agents. Additionally, the surfaces of the bonded aluminum materials were subjected to a 10 min oxidation process, followed by silanization with APTES and GPTMS silane agents. The tensile test performance of single-lap joints, bonded using chemically surface-treated aluminum and composite adhesives containing 2 wt.% chemically treated carbon fibers, was experimentally investigated. According to the contact angle measurement results obtained in this study, aluminum materials subjected to oxidation treatment exhibited superhydrophilic behavior, whereas materials subjected to silanization displayed hydrophilic behavior. A similar trend was observed in the fibers. The performance of adhesive joints increased by approximately 14% when only the aluminum materials underwent oxidation treatment. Moreover, the addition of 2 wt.% carbon fibers to the adhesive enhanced the joint performance by approximately 31%. However, when oxidation treatments of varying durations were applied to both the aluminum materials and the fibers, the joint performance improved by approximately 35% to 40%. When silanization treatments were applied in addition to the oxidation treatments on aluminum and fiber surfaces, the joint performance increased by approximately 68% to 70%. These findings were corroborated through analyses performed using 3D profilometry and Scanning Electron Microscopy (SEM) imaging.

In the present study, chemically surface-treated nanoparticles and nanofibers were added to the adhesive to improve the performance of the two-component structural adhesive. In the study, DP460 structural adhesive was used as adhesive, functionalized Multi Walled Carbon Nanotubes (MWCNT-COOH) with COOH and carbon fiber (CF) chemically surface treated with HNO3 solution were used as nanostructures. In the experimental study, eight different parameters were investigated as the nanostructure was (i) undoped, (ii) 1 wt% MWCNT-COOH added, (iii) 1wt%. untreated CF added, (iv) 0.5 wt% chemically treated CF added, (v) 1 wt% chemically treated CF added, (vi) 2 wt% chemically treated CF added, (vii) 0.5 wt% MWCNT-COOH and 0.5 wt% chemically treated CF added, and (viii) 1 wt% MWCNT-COOH and 1wt% chemically treated CF added. According to the results of the study, adding nanoparticles to the adhesive increases the performance of the adhesive by about 12%, while adding nanofibers increases the performance of the adhesive by about 18%. In addition, increasing the inertness and wettability of nanofibers by chemical treatment, as well as the use of nanoparticles and fibers together, significantly increases the performance of the adhesive. In addition, the obtained results were supported by fourier transform infrared spectroscopy (FT-IR) analysis and scanning electron microscopic (SEM) analysis.

In materials science, the increasing use of lightweight and multi-material structures has made improving the interfacial bonding characteristics of polymer-based adhesive systems increasingly important. Accordingly, chemical surface activation and interfacial engineering strategies have attracted considerable attention for enhancing polymer–fiber compatibility and adhesion performance. However, the combined effects of fiber content, surface treatment, and orientation on adhesion behavior remain insufficiently understood. In the present study, natural fibers obtained from the rachis part of the palm tree were chemically modified and incorporated into an epoxy adhesive matrix to investigate the effect of surface functionalization on polymer–fiber interfacial adhesion. In the first stage, the effects of fiber ratios (5–20 wt%) and chemical surface treatments (methanol cleaning and methanol +2–6% HNO₃) on adhesion behavior were evaluated. Tensile tests showed that specimens treated with methanol cleaning followed by 4% HNO₃ oxidation and containing 10 wt% fiber exhibited an approximately 48% increase in failure load compared to neat joints. In the second stage, the influence of fiber orientation (0–90°) was examined using the optimized parameters. The results indicate that interfacial load-transfer capability increased as the fiber orientation approached perpendicular alignment, reaching maximum performance at 90°. Based on SEM observations, nitric acid treatment was found to increase the surface roughness of the fibers and strengthen the polymer–fiber interfacial bond. FTIR, XPS and contact angle measurements suggested the development of oxygen-containing surface functionalities and improved wettability, consistent with enhanced interfacial adhesion. These findings demonstrate that appropriate chemical surface treatment, fiber content, and orientation can effectively enhance the interfacial adhesion and bonding efficiency of epoxy-based adhesive systems, providing practical guidance for the design of high-performance bonded structures.

Araştırmada geliştirilen aktif öğrenme etkinlikleri 5E modeli esas alınarak oluşturulmuştur. Etkinlikler, öğretmen adaylarının çözeltiler konusu başarılarına olan etkisini belirlemek amacıyla Bayburt Üniversitesi Bayburt Eğitim Fakültesi Fen Bilgisi Öğretmenliği Anabilim Dalı’nda öğrenim gören birinci sınıf öğrencilerine uygulanmıştır. Bu anabilim dalında birinci öğretimde öğrenim gören öğrencilerden rastgele seçimle deney (24) ve kontrol (25) grupları oluşturulmuştur. Deney grubunda çözeltiler konusu 5E modeline uygun olarak hazırlanan etkinliklerle, kontrol grubunda ise geleneksel yaklaşımla işlenmiştir. Daha sonra çalışmada konu ile ilgili olarak geliştirilen kavram başarı testi ön test–son test olarak uygulanmıştır. Deney ve kontrol grupları arasında istatistiksel olarak önemli bir farkın olup olmadığını belirleyebilmek amacıyla veriler bağımsız gruplar t-testi ile analiz edilmiştir. Sonuçlarının analizinden deney ve kontrol grupları arasında istatistiksel olarak anlamlı bir farkın olduğu görülmektedir (t= 4,542; p= 0,000). Uygulama sonrasında deney grubunda ortalama doğru cevaplanan soru sayısı 14,58 kontrol grubunda ise 10,08 olarak gözlenmiştir. Bu sonuçlar dikkate alındığında uygulama sonrasında deney grubunun kontrol grubundan daha başarılı olduğu söylenebilir. Yani çözeltiler konusu ile ilgili kavramların anlaşılmasında 5E modeli esas alınarak hazırlanan etkinliklerin geleneksel yaklaşıma oranla daha etkili olduğu ileri sürülebilir.