Projects – Ayşe Çelik Bedeloğlu's Group

Graphene oxide and zinc oxide decorated chitosan nanocomposite biofilms for packaging applications

22 Ocak 20203 Şubat 2020 tarihinde gönderildi admin tarafından Bir yorum yapın

Abstract:

Recently, due to sustainable development and environmental protection policies, there is increasing interest in the development of new biodegradable polymer-based multifunctional composites. Chitosan is one of the most remarkable and preferred biopolymers, which is environmentally friendly as well as renewable, biocompatible, and inexpensive. Though it has a wide range of potential applications, the major limitation of chitosan – the problem of poor mechanical performance – needs to be solved. In this work, graphene oxide was first produced and then used to manufacture a chitosan/graphene oxide/zinc oxide composite film through a casting method. The properties of the chitosan film and the chitosan/graphene oxide/zinc oxide composite film were investigated using Fourier transform infrared spectroscopy, mechanical, thermal gravimetric, and ultraviolet (UV)-visible spectroscopy analyses. The results showed that the incorporation of graphene oxide and zinc oxide into the chitosan matrix resulted in enhanced mechanical properties and thermal stability of chitosan biocomposite films. The graphene oxide- and zinc oxide-reinforced chitosan film showed 2527 MPa and 55.72 MPa of Young’s modulus and tensile strength, respectively, while neat chitosan showed only 1549 MPa and 37.91 MPa of Young’s modulus and tensile strength, respectively. Conversely, the addition of graphene oxide decreased the transmittance, notably in the UV region.

Keywords: bio-nanocomposite; chitosan; graphene oxide; packaging film; zinc oxide

Published Online: 2020-01-13 | DOI: https://doi.org/10.1515/polyeng-2019-0240

Kauçuk Sektöründe Uygulanan Test Yöntemleri Semineri

14 Haziran 20193 Şubat 2020 tarihinde gönderildi admin tarafından Bir yorum yapın

Polyimide-Coated Fabrics with Multifunctional Properties: Flame Retardant, UV Protective, and Water Proof

21 Eylül 201826 Temmuz 2019 tarihinde gönderildi admin tarafından bir yorum

Multifunctional technical textiles are of great interest both by industry and academia and these products are considered as high value‐added products that contribute to the economies of countries. In this study, polyamic acid (PAA) was synthesized through polycondensation of pyromellitic dianhydride (PMDA) and 4,4′‐oxydianiline (ODA) in dimethyl acetamide (DMAc) at low temperature. Then, PAA was coated onto woven cotton and polyester fabric by padding technique. Finally, polyimide (PI)‐coated multifunctional cotton and polyester fabrics were obtained by an easy coating technique and low‐temperature imidization. Thus, low cost, easily accessible and widely used cotton and polyester fabrics were converted to high‐performance textile products, which are flame retardant, UV protective, acid resistant, and waterproof. The chemical, thermal, morphological, optical, mechanical, wettability, chemical resistance, and flame retardancy properties of developed fabrics were investigated. Optical results showed that both PI‐coated cotton and polyester fabrics are UV‐A protective compared to noncoated fabrics. Moreover, PI‐coated samples have high contact angles which are 111.43° and 113.40° for PI‐coated cotton (PI‐c‐C) and PI‐coated polyester (PI‐c‐PET), respectively. Young’s modulus of PI‐c‐PET fabrics increased four times more than noncoated polyester fabric. PI coating changed the burning behavior of both cotton and polyester fabrics in a positive way. All the test results showed that these developed multifunctional textile products might find an application in different industrial areas such as automotive, aerospace, protective clothing, and so on due to easy and inexpensive production techniques and also superior properties.

Hiçyılmaz, A., Y. Altin, and A. Çelik Bedeloğlu ,2019. 47616.

Link: https://onlinelibrary.wiley.com/doi/full/10.1002/app.47616

In Situ Graphene Oxide Reinforced Poly (Urea – Formaldehyde) Microencapsulation of Epoxy

21 Eylül 20185 Eylül 2019 tarihinde gönderildi admin tarafından bir yorum

In this study, graphene oxide (GO) reinforced epoxy loaded poly(urea-formaldehyde) microcapsules have produced by easy and cost-effective one step in-situ emulsion polymerization method without emulsifier agent. Low amounts of GOhas incorporated into microcapsules without pre-treatment or ultra-speed agitation step. The effect of GO reinforcement on microcapsule size, shell structure, morphology, and thermal behaviour analyzed with Fourier transform infrared spectrometer (FTIR), scanning electronic microscope (SEM) and thermal gravimetric analysis (TGA), respectively. Results revealed that obtained microcapsules are resistant up to 225 °C. Besides, also, the addition of a certain amount of GO (0.5%, wt/ wt) forms pretty small sized (3-4 µm) microcapsules with a smooth surface, since GO nanoparticles act as a surfactant material. On the other hand, by increasing the amount of GO up to 1% (w / w), higher shell thickness was caused due to the coating of the GO layers into the shell. Produced GO-reinforced epoxy loaded microcapsules could be used in self-healing composites and also anticorrosion coatings.

Hiçyılmaz, A. and A. Çelik Bedeloğlu, Vol. 16. 2019. 07-13.

Link: http://www.materialsciencejournal.org/vol16no1/in-situ-graphene-oxide-reinforced-polyurea-formaldehyde-microencapsulation-of-epoxy/

Reduction of Graphene Oxide Thin Films Using A Stepwise Thermal Annealing Assisted by L-Ascorbic Acid

21 Eylül 201826 Ağustos 2019 tarihinde gönderildi admin tarafından Bir yorum yapın

Tas, Mahmut, Yasin Altin, and Ayşe Celik Bedeloglu. “Reduction of graphene oxide thin films using a stepwise thermal annealing assisted by l-ascorbic acid.” Diamond and Related Materials 92 (2019): 242-247.

Link: https://www.sciencedirect.com/science/article/pii/S0925963518308537