LEE- Yenilikçi Teknik Tekstiller-Yüksek Lisans
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ÖgeDevelopment and application of reactive dye microcapsules for cotton fabric dyeing(Graduate School, 2024-06-25)Hızla artan dünya nüfusuyla birlikte tüketici sayısı da artmaktadır. Tekstil sektörü dikkate alındığında diğer doğal liflere göre en yaygın kullanılan doğal elyaf pamuktur. Sunulan çalışmada, havlı kumaşların renklendirilmesinde kullanılan reaktif boyarmaddelerin mikrokapsül teknolojisi ile kapsüllenerek boyama banyolarında kullanılması, bu sayede de çevre dostu bir proses elde edilmesi amaçlanmaktadır. Tekstil sektöründe pamuk boyamada kullanılan reaktif boyarmaddeler genellikle üçlü karışımlar halinde uygulanmaktadır. Bu boyarmaddeler çoğunlukla otomasyona uygun olmayan toz halinde HT makinalarına beslenmektedirler. Reaktif boyamada uygulanan boyama reçetesinde kullanılan boyarmaddelerin %100'ü pamuğa bağlanamaz. Maksimum %70'i pamuğa bağlanır. Boyarmaddelerin geri kalan %30'u su fazına geçer. Bu su fazına geçen boyarmaddeler suda çözünmeyen ve arıtılması zor olan maddeler içermektedir. Aynı zamanda çevresel atık yükünü de artırmaktadır. Çalışma kapsamında reaktif boyaların mikrokapsül teknolojisi ile kapsüllenmesiyle hem kullanılan boya miktarının hem de çevresel atık yükünün azaltılması amaçlanmaktadır. Bu sayede boya tasarrufu sağlanacaktır. Tekstil endüstrisi, çevresel açıdan sürdürülebilir ve enerji açısından verimli yeni üretim yöntemleri geliştirmekte ve yenilemektedir. Bu yeni yöntemler sektörün çevresel etkisini azaltırken pazardaki rekabet gücünü de artıracaktır. Tekstil sektörü her ne kadar geleneksel yöntemlerden vazgeçmek istemese de günümüz teknolojisinde kullanıcı taleplerine cevap vermek ve pazar payının arttırılması önemlidir. Değişen dünyada, projenin başlangıcından itibaren ortaya çıkacak yeni ürün, sadece yeni ürünleri esas almak değil, aynı zamanda temiz enerji, temiz üretim, sürdürülebilir üretim, asgari düzeyde anlayışa sahip olmak açısından da tamamen bu kavramlara dayalı olacaktır. Proje kapsamında detaylı literatür araştırması yapılmıştır. Günümüzde pigment boyarmaddelerinin kapsüllenmesine yönelik çalışmalar oldukça nadirdir. Proje kapsamında gerçekleştirilecek çalışmanın ilklerden biri olması hedefleniyor. Projenin sonucu daha sürdürülebilir bir üretim yöntemi yani konvansiyonel boyama sırasında karşılaşılan enerji, su ve zaman kaybı nedenlerinden uzaklaşarak daha hedefe yönelik bir üretim elde edilmesidir. Projenin beklenen sonucu Avrupa ve ABD test standartlarına uygun, çevreye ve insan sağlığına zarar vermeyen yenilikçi bir üründür.
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ÖgeDevelopment and characterization of surgical locally oxidised regenerated cellulose hemostats(Graduate School, 2024-07-25)Blood is not only a special fluid that transports gases and nutrients but is also responsible for immune control and hemostatic response. Generally, mild bleeding can be stopped by congenital clotting. However, excessive blood loss can cause morbidity (illness) and even mortality (death). Therefore, when haemorrhage occurs, there is a critical time window in which effective treatment must be given to save lives. Uncontrolled excessive bleeding is a life-threatening emergency scenario that significantly impairs patients' survival within the first 48 hours and causes millions of deaths worldwide each year. Large-scale bleeding in battlefields, traffic accidents and during surgical operations can cause high blood loss, which adversely affects physiological processes in the body. With excessive blood loss, there is a decrease in the amount of blood carrying nutrients and oxygen necessary for the metabolic activities of cells in tissues and organs, and metabolic wastes produced by cells begin to accumulate in the intercellular space. If bleeding cannot be prevented for a long time, the blood necessary for the heart to function itself cannot be supplied and bleeding may result in death. In addition, uncontrolled bleeding in patients with coagulopathy is associated with massive bleeding in emergency situations. Excessive bleeding may disrupt the hemodynamics of patients and may require additional blood transfusion. Prolonged treatment may cost life. Therefore, it is critical to stop bleeding in emergencies, especially in cases of organ trauma. In addition, uncontrolled bleeding is not only a life-threatening situation for patients, but also a great financial burden for health services. In this context, hemostatic agents are vital for the rapid prevention of bleeding. Hemostatic materials are generally produced from natural materials such as chitosan, cellulose, starch. Existing hemostatic agents have disadvantages such as acidity, surrounding cell damage, acute/chronic inflammation, thrombogenic complications, non-biodegradability, limited application methods, short shelf life and high cost and impose a serious cost on health expenditures. In this respect, it is important to develop materials with low cost and hemostatic properties to stop bleeding at the time of injury. The main aim of this project is to produce an absorbable hemostatic agent from sustainable natural origin cellulosic fibres obtained from cellulose wastes and to quickly stop and prevent bleeding in tissues. These hemostatic agents produced from polysaccharides or other biopolymers are expected to have properties such as biodegradability, biocompatibility and non-exothermic reaction, and these issues have become the focus in the development of new generation hemostatic materials. In this study, it is planned to produce a non-woven, absorbable hemostatic material that accelerates plasmination for the first time by using TENCEL fibre, which is produced from polysaccharide type materials, sustainable regenerated cellulose obtained from cellulose wastes, provides more hygienic properties by creating an environment less favourable to bacterial growth and has the potential to reduce the risk of irritation and negative effects on the body by providing a smoother surface and softness. It is aimed to use TENCEL fibre as the main material in the production of cellulosic hemostatic agent and to develop surgical local hemostat by oxidation of the felt to be obtained. Thus, it is aimed to evaluate innovative natural origin sustainable fibres in the production of medical textile products and to transform them into value added products. As a start, Tencel fibre supplied by Göl Iplik, one of our project sponsors, was purchased in fibre form and delivered to Karınca Filter facilities, also one of our project supporters. Our Tencel fibre was taken to the Dilo machine in the facility where fiber preparation, carding, cross-laying, lap drawing and needling processes were carried out respectively. Firstly, 16 plies were tried in cross-laying, but since the thickness of the product was too high, the number of plies was also tried as 12 and 8. As the tencel fibre gains volume after passing through the carding machine, the product was also evaluated by needling at the same time. Two different drums of the needling section were evaluated and our 8-layer product was needled as 49K and 16K respectively and formed as 2 different samples. Finally, 4 types of samples were chosen for the subsequent studies: 12 layers un-needled, 8 layers un-needled, 8 layers 49K needled and 8 layers 16K needled. Afterwards, by comparing the samples chosen with their equivalents in the market, it was decided that the 8 ply 16K needled sample was the most suitable one with the properties required. 8 ply 16K needled sample, which is accepted as the optimum sample, has been oxidised. The oxidation process was carried out in a closed system in a stainless metal boiler in Yucel Medical facility. In the closed boiler, 250 grams of nitrogen dioxide (NOx) gas was given for 3 kg of nonwoven product and the trapped product was kept at a temperature of 20-25 C for 24 hours. Afterwards, it is removed from the boiler and placed in a container containing approximately 10 litres of ethyl alcohol by an operator using a mask as soon as it is removed. It is kept in the container full of ethyl alcohol for 30 minutes. Afterwards, the pH value is measured, if it is not suitable, ethyl alcohol washing is continued again. After washing 4 times with ethyl alcohol, the desired pH value is reached. The pH value is targeted between 2,8 and 4. The reason for this is the antibacterial effect of the product between these standards. Then it is left to dry in a clean environment in a laminal cabinet. It is dried and kept for about 12 hours. After nonwoven products of suitable texture formed by using Tencel fibre were oxidised under suitable ambient conditions, carboxyl ratios, optimum pH and solubility were achieved. Moreover, loss on drying test, nitrogen content, formaldeyhyde test is performed, and the results are in the standards according to USP28 (United States Pharmacopeia) Pharmacopoeia standard. Carboxyl test was applied on the dried product to determine carboxyl ratios. The purpose of this is to see whether the product complies with the USP28 (United States Pharmacopeia) Pharmacopoeia standard. The appropriate carboxyl amount indicates that the product can be absorbed in the body. Since pH is a crucial factor in determining a material's biological compatibility and functioning, pH test was applied. The degree of oxidation and the presence of acidic groups in oxidized regenerated cellulose might influence how the material dissolves or is suspended in water. Solubility testing of oxidised regenerated cellulose (ORC) is necessary to evaluate its performance in medical applications. Drying loss test was applied to the newly produced product and the product on the market. Specific weights of materials taken separately from both samples will be dried at specified temperatures for 2 hours. After drying, the weight of the materials will be measured again. Nitrogen content analysis on oxidised regenerated cellulose is a fundamental analytical technique that supports quality assurance, regulatory compliance and research efforts related to this important biomaterial. That is why we did the nitrogen content test. Formaldehyde testing on oxidised regenerated cellulose is essential to verify compliance with safety regulations, ensure patient safety and maintain the quality and integrity of the material for medical applications. For this reason, we performed the formaldehyde test. In the method used in the production of the hemostatic agent developed within the scope of the project, the information obtained from the literature was combined with the research experience of the project team and the process parameters were determined and optimised. In addition, tests of the produced hemostatic material and a commercial material were carried out in accredited laboratories and the potential for commercialisation was evaluated by comparing their performances.
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ÖgeFabrication, characterization and drug release behaviors of electrospun PEtOx/Flubendazole nanofibrous webs(Graduate School, 2024-07-11)Filarial infections in humans result in deteriorating health conditions for over a hundred million people, particularly in some low-income countries in Africa and Asia, notably sub-Saharan Africa. They lead to diseases like lymphatic filariasis and onchocerciasis, with 120 million people currently afflicted by this disease. Flubendazole is the most appealing benzimidazole drug for the treatment of filarial parasites. It is also licensed and marketed in Europe as Fluvermal to treat intestinal nematodes in humans. However, it is a benzimidazole methylcarbamate anthelmintic with poor water solubility and is included in the Biopharmaceutics Classification System (BCS) class IV compound. For this reason, it has poor solubility in the aqueous systems formed in the gastrointestinal tract, shows poor absorption in the blood circulation and therefore its bioavailability is extremely low. These drawbacks can be deal with by the use of amorphous solid dispersions (ASD), which is a promising approach to improve the oral bioavailability of poor water-soluble drugs. ASDs prepared with water-soluble polymeric carriers are used to enhance the dissolving ratio and potentially bioavailability of such hydrophobic drugs. Electrospun nanofiber-containing ASDs possess exceptional physical stability due to the molecular distribution of the drug within the fibers, and the polymer chains provide a steric barrier against the recrystallization of the drug. Further, it improves drug dissolving rates in aqueous conditions due of their three-dimensional construction and high interconnected porosities with configurable pore sizes, allowing for effective surface functionalization. The solvent used to prepare polymeric solutions has a crucial impact on achieving extremely high drug loading and electrospinnability. Over the past decades, poly(2-ethyl-2-oxazoline) (PEtOx) has found application as a polymer in biomedical and pharmaceutical fields, particularly for delivering hydrophobic drugs, proteins, and nucleic acids. It has exceptional biocompatibility, lack of toxicity and anti-fouling properties. Furthermore, various researches on PEtOx have stated that PEtOx has great stability in body, and no tissue destruction, being the polymer safe for use for body. In this thesis, ASDs were developed and fabricated by loading PEtOx with 40%, 45%, 50%, or 55% wt. flubendazole using the electrospinning method. The resulting nanofiber membranes were examined in detail in three different surface forms. Physical, morphological, and thermal characterizations of the surfaces were conducted, and the effects of using PEtOx, flubendazole ratio, and surface form on in-vitro drug release behaviors were investigated. Scanning Electron Microscope (SEM) analysis showed that homogeneous and continuous fibers were obtained on the membrane surfaces regardless of the flubendazole ratio. Crimped fibers were observed in the samples with the cut surface form, while flattened fibers were seen in the ground samples. The fiber diameter measurements indicated that the fiber diameter tended to increase with a higher flubendazole ratio, and although no difference was observed in the cut samples, flattening was noted in the grinded samples. When examining the results of Differential Scanning Calorimetry (DSC) analysis, it was found that glass transition temperature (Tg) values were between the Tg of pure flubendazole and PEtOx. This indicates that both components are blended at a molecular level. On the other side, it was found that Tg values increased with the flubendazole ratio, regardless of the surface form. The surface form did not show a significant affect on Tg values. Evaluating the drug release profiles revealed that the release rate was decreased by the increasing flubendazole ratio, whereas the fastest release obtained in the cut surface form. Additionally, while crystalline flubendazole achieved a release rate of 2.12 mg/mL at the 60-minute mark, the ASDs produced with different flubendazole concentrations exhibited drug release in the range of 7.46-14.48 mg/mL which showed that PEtOx loaded with flubendazole exhibited a higher release amount. In this context, it is thought that ASD systems developed within this thesis represent an innovative design with promising potential for the release of poorly soluble drug.
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ÖgeDevelopment of a gas sensing nanofibrous membrane for asthma detection(Graduate School, 2024-01-09)In this study, a membrane consisting of zinc oxide nanofibers was formed through electrospinning process in order to be used in gas sensing tests for determining the nitrogen oxides (NOx) gases which exist in the exhaled breath of asthma patients more than those of healthy people. Various attempts had been made to get the best result concerning the ease and continuity of the process at production step. Polyvinyl alcohol (PVA) and Zinc acetate dihydrate (Zn(OAc)2·2H2O) were used as precursor substances for membrane formation. Zinc oxide (ZnO) nanofibers-based membranes were obtained after calcination process. In order to determine the best polymer concentration for electrospinning solutions; PVA solutions at concentrations ranging from 7% to 20% (w/v) were prepared, firstly. According to the rheological study results, 15% PVA (w/v) was found the most proper concentration among them in terms of the level of the polymer chain entanglement that provided sufficient viscosity. Four different mass ratio of Zn(OAc)2·2H2O with respect to the polymer concentration; 1:0.5, 1:1, 1:1.5 and 1:2 were introduced to the solutions for finding the most proper electrospinnable solution for ZnO formation. Some physicochemical and rheological analyzes such as pH, conductivity, viscosity and surface tension measurements were carried out in order to evaluate the electrospinnability of each solution and also to suggest the possible reactions of intermediate products formed in aqueous medium. The conductivity, surface tension and viscosity values of the solutions increased with an increase in Zn(OAc)2·2H2O concentration; however, a decrease in pH was observed. This was probably due to the consumption of the hydroxide ions in PVA / Zn(OAc)2·2H2O solutions, in order to form an aqueous intermediate product, zinc hydroxide Zn(OH)2. Moreover, thermogravimetric analysis (TGA) was carried out for defining suitable thermal parameters for calcination process. The scanning electron microscopy (SEM) analysis was employed to the membranes prepared both before and after calcination processes. As far as the all analyzes and measurements were concerned, it was estimated that the formation of ZnO overlapped with the late decomposition of PVA during the thermal process, around 600°C. The formation of ZnO proceeded through the transformation of Zn(OH)2 by loss of water molecule. Among the prepared samples, 15% PVA solution with equivalent amount of Zn(OAc)2·2H2O showed the best performance considering the fineness of nanofibers and the amount of products or reactants produced or used; however, the continuity and stability at the region of taylor cone and jet were not found satisfactory enough. That is the reason why, various attempts were applied to all samples in order to get more optimized electrospinning process. In the last part of the study, the solutions were re-prepared and investigated in acidic and basic medium, in water:ethanol binary solvent system and in the presence of surfactant. After conducting all necessary analyses, it was concluded that adding 1% (w/v) non-ionic surfactant to the solution of 15% PVA: 15% Zn(OAc)2·2H2O provided more stable and continuous electrospinnability predominantly thanks to the decrease in surface tension of the solution.
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ÖgeInvestigation of physical performance of denim fabrics washed with sustainable foam washing(Graduate School, 2024-01-16)Denim fabrics, which have a great importance in the textile industry, are always developing from past to present. Denim fabrics, which have been used for a long time and have not lost their popularity, have a very wide usage area today. Even if the perception of fashion changes, denim products have always maintained their place in the industry. Although denim fabrics are most frequently used as trousers in the textile industry, they are also widely used in products such as dresses, skirts, bags, home accessories and shoes. In addition to its product diversity, it is highly preferred in the textile industry due to its durability. The most important stage that makes denim fabrics visually appealing to the fashion industry is the washing process. The final appearance of the denim is achieved by giving the desired effects to the product with the washing processes carried out at the final stage. With different washing methods, denim is given many visual effects such as worn, vintage, faded, shiny etc. A lot of water and chemicals are being used during denim washing processes, and this problem has been a subject of many researches for a long time. Re-using the waste obtained from denim washing causes another energy loss. This problem exists not only in denim manufacturing but also in many areas of the textile industry. When the damage caused to the environment by the textile and apparel clothing industry is examined, many concepts such as sustainability, ecological production and waste-free production have come to the fore. For this reason, many companies, factories and organizations are looking for new researches and initiatives to do their production using less water, chemicals and energy. Denim production is one of the process that consume much water and chemicals in the textile industry. Many denim manufacturers and brands are still looking for new solutions to reduce this damage. Today, alternative and sustainable searches still continue. Stone washing is one of the most common washing methods used in the denim industry for many years. Stone washing is being processed in industrial washing machines by using pumice stones. Washing times vary depending on the effect desired to be achieved. With the rotation inside the industrial washing machines, dyestuff on the garment wears off due to the friction between garment and stones and the desired effect is achieved. During this process, a lot of water is being consumed and the pumice stone damages the garment when friction is high. Therefore, after the washing process is completed, pumice stones must be carefully removed from the garment and should be cleaned. The process of removing pumice stone requires another rinsing process, and pumice stone that is not completely cleaned from the garment can be harmful for human health and the product. In addition, pumice stone becomes unusable by shrinking or decomposing after a few washing processes. Unusable stones causes waste problem, and also recycling or stock processes of these left stones causes another workload and energy loss. For this reason, washing processes that can be an alternative to stone washing have been the subject of many searches since the past. There are methods that have been developed and are still being developed by many researchers to reduce the use of water and chemicals or to prevent the use of pumice stones. The aim of this thesis, in cooperation with Ereks Blue Matters Factory, is to offer a new sustainable method in which less water and chemicals are being used and the use of pumice stones is eliminated, as an alternative to stone washing. For this purpose, a new technology, the foam washing method, was investigated and washing experiments were carried out. Washing trials were carried out to obtain the effects given by friction of the pumice stone on the fabric in industrial washing machines, by spraying foam on the same washing machines. In the study, firstly stone washing and foam washing recipes and washing process stages were compared. Secondly, the physical properties of the fabrics obtained from stone washing and foam washing were analyzed and compared with each other. For this study, 7 different denim fabrics with different compositions and weights, which are most commonly used in production at the Ereks Blue Matters factory, were selected. Two of the same fabrics were produced, processed as same until washing stage. For the washing process, one fabric was washed with stone while the other fabric was washed with foam. Washing trials were carried out separately for 30, 60 and 90 minutes for each fabric type. As a result of the washing trials, a total of 42 washed denim fabric samples were obtained, 21 stone washed and 21 foam washed. In order to compare the physical performances of obtained samples, color fastness to domestic and commercial washing, color fastness to rubbing, abrasion resistance according to the Martindale method, color analysis with spectrophotometer, stiffness of fabric by the circular bend procedure, tear and tensile strength tests were carried out in Istanbul Technical University Textile and Apparel Quality Control Laboratory. With James H. Heal Titan machine, tear strength test according to TS EN ISO 13937-2 and tensile strength test according to TS EN ISO 13934-2 were evaluated. Abrasion test according to Martindale method was evaluated in James Heal Martindale & Pilling Tester according to TS EN ISO 12947-2. Color fastness to rubbing test was evaluated in SDL Atlas Crockmeter according to TS EN ISO 105-X12. Color fastness to washing test was evaluated in Linitest machine according to TS EN ISO 105-C06, stiffness of fabric by the circular bend procedure was evaluated in A&T Machine according to ASTM D4032 and color analysis was evaluated with Datacolor 650ᵀᴹ spectrophotometer. Test results were compared according to washing durations 30, 60 and 90 minutes for foam and stone washed fabrics. When the test results were evaluated, it was seen that less water was used during the foam washing process compared to stone washing. When the test results were compared, the tear strength test results were higher in all fabrics washed with foam for both weft and warp yarns. Tensile strength test results varied and no generalizable result could be determined for foam or stone washed fabrics. When the wet/dry rubbing fastness and washing fastness test results were evaluated, it was observed that the rubbing and washing fastness values of foam washed fabrics were generally better than stone washed fabrics. As a result of the evaluation, it was determined that the rubbing and washing fastness values of foam washed fabrics were better or the same as stone washed fabrics. After abrasion resistance test according to the Martindale method, no yarn breakage was observed for foam 40,000 cycles. For all fabrics, weight loss was observed as the rpm increased, but a regular rate was not detected in decreasing weights. In most of the tested fabrics, it was seen that the weight loss after 15,000 rpm was less for foam washed fabrics than for stone washed. It was determined that only for 4 types of foam washed fabrics, the weight loss was higher than stone washed, but this difference was less than 3%. When all test results were evaluated, it was determined that the physical properties of denim fabrics washed with the foam washing method were preserved or better. Therefore, it has been proven that the new method can be used in the industry. Although the test results of foam washed fabrics are not significantly superior to stone washed ones, the difference in the ratio of water and chemicals used is quite high. Also, the use of pumice stones is eliminated with the foam washing process, and energy consumption in the process of removing pumice stones or stock waste will be prevented. When these results were evaluated, it was determined that the foam washing method can be used as a sustainable alternative to the stone washing method. Thus, an environmentally friendly method has been developed which can be accepted in the textile industry.