Person: ORHAN, MEHMET
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ORHAN
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MEHMET
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Publication Development of polycaprolactone-based electrospun ph-sensitive sensors as instant colorimetric indicators for food packaging(Wiley, 2023-06-01) Güçlü, Nihal; Düzyer Gebizli, Şebnem; DÜZYER GEBİZLİ, ŞEBNEM; Orhan, Mehmet; ORHAN, MEHMET; Mühendislik Fakültesi; Tekstil Mühendisliği Bölümü; 0000-0003-3737-5896; 0000-0001-8043-4148; AAG-8034-2021; AFO-0698-2022In the present study, polycaprolactone/polyethylene glycol (PCL/PEG) electrospun nanofibres with different anthocyanin (1%, 2%, 3%, and 5%) were fabricated for the instant measurement of pH, especially for applications-such as food freshness detection-where quick response is required. The solution, surface, chemical, thermal, wettability, mechanical, and release properties of the samples were evaluated by viscosity measurements, scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), contact angle measurements, and tensile tests, respectively. The colorimetric analyses were also investigated against the solutions at different pH values and bacterial solutions. Finally, the on-site performance of the sensor was evaluated. Anthocyanin addition initially lowered the solution viscosity, resulting in thinner fibres with a diameter of 288 nm. The diameters were increased up to 395 nm with the increasing anthocyanin. Anthocyanin addition enhanced the wettability and the mechanical properties, and the contact angles decreased to 43 degrees. The highest modulus was observed for 1% anthocyanin, with a value of 6.162. The release experiments revealed that the anthocyanin-loaded samples released a large amount of anthocyanin (between similar to 12% and 38%) in the first 15 s. The colorimetric analyses showed that PCL/PEG nanofibre mats with 2% and 3% anthocyanin concentrations were the most capable pH-sensitive sensors for detecting pH changes from 2 to 8. As a result, it can be concluded that 3% anthocyanin is the threshold value for the production of the anthocyanin-loaded nanofibre mats, and these structures are promising for the instant detection of pH proved by the on-site application.Publication Wrinkle recovery and performance properties of viscose surface treated with different crosslinking agents(Gazi Üniversitesi Mühendislik Mimarlık Fakültesi, 2021-01-01) Orhan, Mehmet; ORHAN, MEHMET; Mühendislik Fakültesi; Tekstil Mühendisliği; 0000-0001-8043-4148; AAG-8034-2021Cellulosic-based surfaces, such as viscose and linen, tend quickly to wrinkle, and this is an undesirable property during uses. In this study, it is aimed to investigate their effects on formaldehyde amount, color, tear and tear resistance, modulus of elasticity, softness, and wrinkle recovery angle of viscose surface after applying three different cross-linking chemicals. It has been observed that cross-linking agents had bound to viscose surface, and cross-links were formed between adjacent fibers. Although free formaldehyde values were positively below 75 ppm in all applications, it was seen that color difference and yellowing continued to be a problem. Considering the physical properties, which is one of the other negative results, the improvements in breaking and tearing strength were obtained compared to the untreated surface. While lower bending rigidity values were measured for all applications, surfaces had a softer handle after treatments. At the same time, the higher wrinkle angle values were achieved on the surfaces with an increase in concentration. It was determined that imidazoline gave the best wrinkle angle values among cross-linkers. The results showed that cross-linkers made a positive contribution to the wrinkle property of the viscose surface.Publication Improving the effectiveness of finishing agents by calendering(Amer Assoc Textile Chemists Colorists-aatcc, 2004-10-01) KUT, YAŞAR DİLEK; Güneşoğlu, Cem; Orhan, Mehmet; ORHAN, MEHMET; Mühendislik Fakültesi; Tekstil Mühendisliği Bölümü; 0000-0001-8043-4148; AAH-4335-2021; AAG-8034-2021; M-2463-2018The mechanical properties of a calendered fabric may vary according to the process parameters. This study evaluated the effects of calendering on the finishing agents and examined the effectiveness of finishing agents after calendering. For this purpose, fabrics impregnated with softener, water repellent, or crease resistant agents at three different concentrations were calendered under optimal process conditions, and the finished properties of the fabrics were measured. The calendering effect on the fabric structure improved the effectiveness of finishing agents even at decreased concentrations.Publication Supercritical carbon dioxide application using hydantoin acrylamide for biocidal functionalization of polyester(Elsevier, 2020-11-01) Orhan, Mehmet; Demirci, Fatma; Koçer, Hasan B.; Nierstrasz, Vincent; ORHAN, MEHMET; Tekstil Mühendisliği Bölümü; Mühendislik Fakültesi; 0000-0001-8043-4148; AAG-8034-2021Biocidal functionalization in polyester fibers is a really tough challenge because of the lack of tethering groups. This study indicated supercritical carbon dioxide application using N-halamine would be an alternative solution for obtaining antibacterial function on the polyester surface. Firstly, N-(2-methyl 1-(4 methyl-2,5-dioxo-imidazolidin-4 yl)propan-2-yl)acrylamide was synthesized and applied to the polyester in supercritical carbon dioxide medium, at 120 degrees C, 30 MPa for different processing times. The addition of N-halamine on the surface significantly brought antibacterial activity against E. coli. The chlorine loadings showed that 6-h exposure time was critical to obtain sufficient antibacterial activity. This treatment caused a reasonable and tolerable loss in color and mechanical properties. But, the durability to abrasion, stability, and rechargeability of oxidative chlorine, and the durability of N-halamine on the surface were remarkably good. Conclusively, it can be available to work on polyester surfaces with resource-efficient and eco-friendly supercritical carbon dioxide technique for getting more functionalization and modification. (C) 2020 Elsevier B.V. All rights reserved.Publication Investigation of poly(lactic acid) nanocapsules containing the plant extract via coaxial electrospraying method for functional nonwoven applications(Sage Publications Inc, 2021-01-25) İbili, Hatice; Daşdemir, Mehmet; Çankaya, I. Irem Tatlı; Orhan, Mehmet; Güneşoğlu, Cem; Anul, Serap Arabacı; ORHAN, MEHMET; Tekstil Mühendisliği Bölümü; 0000-0001-8043-4148; AAG-8034-2021This study focuses on the development of functional nanocapsules via the coaxial electrohydrodynamic atomization (electrospraying) method. These nanocapsules can manipulate nonwoven surface functionality in terms of antibacterial characteristics for medical textile purposes. Electrosprayed nanocapsules were produced from Poly(lactic acid) (PLA) polymer and Plumbago europaea plant extract. Here, we employ optimized solution and process parameters (needle to collector distance, electrical field, application time, and needle dimension) for the coaxial electrospraying process. Different Plumbago europaea extract concentrations and co-fluids' flow rates were investigated as part of the study. Also, the effect of these parameters on capsule morphology and dimension were investigated. After the formation of PLA nanocapsules, morphological and dimensional characteristics were analyzed through SEM, FESEM, TEM images in addition to FTIR and nanosize measurements. According to our findings, a lower co-fluids' flow rate gives the smaller nanocapsules with narrow-sized distribution and desired spherical morphology. Antibacterial efficiency doesn't show any significant difference except the lowest plant extract concentrations. After characterizing the nanocapsules' structures, the core-sheath structure can be clearly identified. Consequently, the desired capsule morphology and size for nanocapsules were accomplished. The antibacterial efficiency of covered surfaces with nanocapsules is up to 80% for Staphylococcus aureus and about 31% for Escherichia coli, even with low pick-up ratios. Even for a very low amount of extract usage, good antibacterial efficiency can be achieved. The application has endless potential in terms of higher concentration and a wide range of chemical usage.