https://hdl.handle.net/20.500.12809/41 2026-04-08T16:08:06Z 2026-04-08T16:08:06Z Durmaz, Sefa Özgenç Keleş, Özlem Aras, Uğur Avci, Erkan Atar, Ilkay https://hdl.handle.net/20.500.12809/10869 2023-08-09T08:59:22Z 2023-01-01T00:00:00Z

Improvement of weavdthering and thermal resistance of wood-plastic composites with iron oxide nanoparticles Durmaz, Sefa; Özgenç Keleş, Özlem; Aras, Uğur; Avci, Erkan; Atar, Ilkay This study comprehensively investigated the effect of iron-oxide nanoparticles (NPs) on weathering durability and thermal resistance of wood-plastic composites (WPCs). The hydrophobic nature of NPs improved the dimensional stability of WPCs. The small size of NPs deposits the voids in the matrix, which helps to increase the mechanical properties, even after weathering test. The decrease of modulus of rupture (MOR) reached up to 16% for control samples, while it was 2% for IO40-1. Despite the intensive weathering conditions, NPs cover the surface of materials like a UV shield, improving WPCs' UV resistance. Moreover, the increase in the wood and NPs content limited the UV degradation, which resulted in lower color changes. The attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) analysis also proved that there were nearly no changes in the characteristic bands of polymer (2916 and 2846 cm−1) and wood (1512 cm−1). The microscopic investigation, however, revealed the deterioration on the surface of WPCs after weathering exposure. Even though UV degradation is inevitable, iron oxide NPs significantly preserved the WPCs surface. However, there were also crack formations, which were also inhibited. On the other hand, NPs decelerated the thermal degradation by acting as a heat barrier. Thermogravimetric analysis (TGA) analysis revealed an increase in the degradation temperature. Limit oxygen index (LOI) values also increased up to 27.6%, which demonstrated an improvement against flammability

2023-01-01T00:00:00Z Keleş, Özlem Özgenç Durmaz, Sefa https://hdl.handle.net/20.500.12809/10745 2024-04-04T08:41:50Z 2023-01-01T00:00:00Z

A Synergic Effect of Water-Based Acrylic Resin with Boric Acid on Leachability Keleş, Özlem Özgenç; Durmaz, Sefa In this study, the Scots pine wood samples were impregnated (single treatment) with boric acid combined with two types of water-based acrylic resin (pure acrylic and semi-translucent acrylic emulsion) to limit the boron leaching and improve the decay resistance. The results showed dimensional stability in anti-swelling efficiency and water absorption improved in wood specimens treated with boric acid and acrylic types. While the leachability was over 90% for only 3% boric acid-impregnated wood (control), it was calculated at 36% for acrylic emulsions-impregnated wood. Although there were no weight losses for the unleached woods, it was up to 9% for leached woods impregnated with acrylic resin and emulsion. The 25% acrylic emulsion had no weight losses after the leaching test for Coniophora puteana and Trametes versicolor. The boric acid combined with acrylic resin can improve the leaching resistance with the synergic effect, enhancing resistance against biological threats.

2023-01-01T00:00:00Z Durmaz, Sefa, Aras, Uğur https://hdl.handle.net/20.500.12809/10558 2023-02-28T08:23:10Z 2023-01-01T00:00:00Z

Effect of Short Glass Fiber Reinforcement on Physical, Mechanical Properties and Fire Performance of Wood Plastic Composites Durmaz, Sefa,; Aras, Uğur Aim of study: This study aimed to improve some physical, mechanical properties, and fire resistance of wood-plastic composites (WPCs) with short glass fiber reinforcement (SGFR). Materials and Methods: The WPCs were reinforced with different ratios of short glass fiber (SGF). The effect of reinforcement on the water absorption (WA), thickness swelling (TS) as physical properties, flexural strength, modulus of elasticity, and tensile strength as mechanical properties were determined. The fire resistance performance was also evaluated by the limit oxygen index (LOI) test. Main results: The reinforcement improved the physical properties. The WA and TS values decreased with increasing glass fiber content. Flexural strength increased up to 28%, while 24% for tensile strength. There was a substantial enhancement in the modulus of elasticity (up to 122%). The glass fiber reinforcement also improved the fire performance of WPCs. Highlights: The higher properties could be obtained by synthetic fiber reinforcement for WPCs.; Çalışmanın amacı: Bu çalışma kısa cam lif güçlendirmesi ile odun plastik kompozitlerinin (OPK) bazı fiziksel, mekanik özelliklerini ve yanma direncinin arttırılmasını amaçlamıştır. Materyal ve Yöntem:OPK’lar farklı oranlarda kısa cam lifleri ile güçlendirilmiştir. Güçlendirmenin fiziksel özellikler olarak su alma, kalınlığa şişme, mekanik özellikler olarak eğilme direnci, elastikiyet modülü ve çekme direncine olan etkisi belirlenmiştir. Yangın direnci performansı ayrıca limit oksijen indeksi (LOI) testi ile değerlendirilmiştir. Sonuçlar: Güçlendirme fiziksel özellikleri iyileştirmiştir. Su alma ve kalınlığa şişme değerleri artan cam lif içeriği ile azalmıştır. Eğilme direnci %28'e kadar yükselirken, çekme mukavemeti %24’e kadar artmıştır. Elastikiyet modülünde önemli bir iyileşme olmuştur (~%122). Cam elyaf takviyesi ayrıca OPK’ların yangın performansını da iyileştirmiştir. Önemli vurgular: OPK’lar için sentetik elyaf takviyesi ile daha yüksek özellikler elde edilebilir

2023-01-01T00:00:00Z Durmaz, Sefa Keleş, Özlem Özgenç Aras, Uğur Erdil, Yusuf Ziya Mengeloğlu, Fatih https://hdl.handle.net/20.500.12809/10485 2023-01-16T08:31:23Z 2022-01-01T00:00:00Z

The effect of zinc oxide nanoparticles on the weathering performance of wood-plastic composites Durmaz, Sefa; Keleş, Özlem Özgenç; Aras, Uğur; Erdil, Yusuf Ziya; Mengeloğlu, Fatih In recent years, wood-plastic composites (WPCs) have become among the most popular engineering materials. Most of their usage areas are outdoors, where they encounter various damaging factors. The weathering conditions cause significant deterioration to WPC surfaces, which negatively influences their service life. In this study, zinc oxide nanoparticles at different concentrations (1%, 3%, 5%, 10%) were added to a high-density polyethylene-based WPC matrix. The effect of zinc oxide nanoparticles on the weathering performance of WPC was evaluated after 840 hours of an artificial weathering test. The highest colour changes (∆E*) were monitored with control samples exposed for 840 hours. Adding zinc oxide nanoparticles improved the ultraviolet (UV) resistance and decreased the colour changes. The wood flour content also affected the colour changes on the WPC surface. A combination of 10% zinc oxide nanoparticles and 50% wood flour content provided the lowest colour changes. The barrier effect of nanoparticles protected the WPC surfaces from UV light. Zinc oxide nanoparticles also positively affected the load transfer, which restricted the reduction in mechanical properties after the weathering test. The degradation on the surface of WPCs was also investigated using attenuated total reflectance-Fourier Transform–infrared analysis. The changes in the characteristic bands of polymer and wood indicated that surface degradation was inevitable. Light and scanning electron microscopy images also demonstrated micro-cracks and roughness on the surface of WPCs. It is concluded that UV degradation is unavoidable, but zinc oxide nanoparticles can improve surface resistance against weathering conditions.

2022-01-01T00:00:00Z