Leak-Proof Fiber-Braided Membrane Production

Leakage-Resistant Fiber Woven Membrane Production In this study, membranes capable of addressing the sealing sector were obtained using nanotechnological electrospinning technique containing activated charcoal-reinforced polyvinylidene fluoride (PVDF) polymer. Activated charcoal was produced from waste materials from shoe manufacturers found as scrap in our environment. Waste materials were converted to suitable powder form through grinding following pyrolysis. Powders of appropriate size were added to PVDF polymer solution at 1%, 5% and 8% ratios to create composite solutions. Leakage-resistant membranes were obtained from the solutions with the aid of an electrical field. This method is simple, cost-effective and sustainable. It can be easily integrated into target applications for leakage-resistant and filtration purposes.

1. Introduction

The concept of leakage resistance is the absence of any seepage in areas clearly separated by boundaries. In this way, it will have served its purpose. For this purpose, sealing elements such as clamps, seals, pipes, plates and membranes are used in sectoral applications [1]. Leakage is an unwanted situation in most sectors. After a flow, product performance can decrease, causing tearing, poor quality, and unwanted problems. Furthermore, if leakage is considered vital, it can lead to electrocution and death of individuals [2]. While many production methodologies exist for leakage-resistant materials, the fact that raw materials to be used are expensive and imported from abroad partially prevents sustainability. However, the main emphasis in our work is to encourage the use of waste materials in many applications. This is because waste indirectly affects us negatively. Recovery of waste materials and creation of quality products through recycling is important. The most striking of these production systems is nanotechnological electrospinning [3]. Nanotechnological electrospinning is a nanofiber membrane production technique using polymeric solutions with the aid of an electrical field. It offers application opportunities suited to virtually all sectors including health, cosmetics, food, filtration and defense. The system simply consists of a syringe pump, power supply and collector plate. It is the simplest and most cost-effective fiber-forming technique. Nanotechnological production provides the most superior performance in sealing applications [4]. With targeted active substances, polymer use and production parameters, optimum membrane quality can be achieved, providing superior sealing. The Taylor cone and nanofiber image are shown in Figure 1.1. [caption id="attachment_157334" align="aligncenter"] Figure 1.1. Taylor cone and nanofiber image [5][/caption] Activated charcoal is a highly absorbent material thanks to its porous structure. It can be obtained from petroleum and coal types. Through a process called pyrolysis, activated charcoal has been obtained from many waste materials from the past to the present. Value-added activated charcoal can be obtained through pyrolysis from different waste materials such as hazelnuts, walnuts, and apricot pits [6]. In our nanotechnological membrane, activated charcoal reinforces the polymer, contributing to membrane strengthening, while allowing the structure to breathe and increasing the membrane's surface area to provide sealing performance. Polyvinylidene fluoride (PVDF) polymer is a hydrophobic water-repellent membrane. It is a polymer frequently preferred in filter applications with superior strength properties and capable of providing sealing performance. In sealing applications, it can adapt to its platform due to appropriate elastic properties. The chemical structure of PVDF is shown in Figure 1.2. [caption id="attachment_157335" align="aligncenter"] Figure 1.2. Chemical structure of PVDF [7][/caption] In this work, activated charcoal was obtained from waste shoe scraps through pyrolysis, the obtained activated charcoal was added to PVDF polymer solution at 1%, 5% and 8% ratios, and membranes were produced using nanotechnological electrospinning technique. Thus, superior performance will be provided with leakage-resistant and filterable membranes.

2. Materials and Methods

2.1 Materials

Waste shoe insoles were collected for activated charcoal production in our study. PVDF polymer was obtained from recycling companies in the sector. Oiled paper was preferred as substrate material in the nanotechnological electrospinning system. Dimethylformamide (DMF) solvent was used to dissolve PVDF polymer.

2.2. Methods

2.2.1 Collection of Waste Shoes

Waste shoe soles resulting from materials of a shoe sole manufacturer operating in Istanbul were collected. And transferred to the production area for pyrolysis. Waste shoe rubber insoles are shown in Figure 2.1.   [caption id="attachment_157337" align="alignleft"] Figure 2.1. Waste shoe rubber insoles[/caption]  

2.2.2 Pyrolysis of Waste Shoe Insoles and Activated Charcoal Production

The collected waste was placed in a pyrolysis machine and heated and burned. Following the burning process, charcoal particles were obtained. Charcoal particles were first ground in a ceramic mortar and then in a ball mill to suitable powder form. As time increased, sizes decreased and powder was reduced to 40 micrometers. Activated charcoal was obtained and prepared for membrane production. Pyrolysis of waste shoe insoles and activated charcoal production are shown in Figure 2.2. [caption id="attachment_157338" align="aligncenter"] Figure 2.2. Pyrolysis of waste shoe insoles and activated charcoal production[/caption]

2.2.3 Production of Nanotechnological Membrane Containing Activated Charcoal

The obtained activated charcoal was weighed on a precision scale at 1, 5 and 8 mg. 10 grams of PVDF was weighed and stirred in 100 ml DMF solvent at 60°C for 12 hours with a heated magnetic stirrer to create a solution. The weighed activated charcoal was added to the solutions to obtain composite solutions. In the nanotechnological electrospinning system, oiled paper was used as substrate material. Working parameters of 1-2.5 ml feed rate, 25-30 kV high voltage and 12-15 cm working distance were selected to obtain membranes. Figure 2.3 shows the stages of nanotechnological membrane production containing activated charcoal. [caption id="attachment_157339" align="aligncenter"] Figure 2.3. Stages of nanotechnological membrane production containing activated charcoal[/caption]

3. Results and Discussion

Surface properties and necessary physical tests of the produced activated charcoal were extracted. Filtration testing was performed as filter material. According to test results, 99.999% particle filtration was achieved. Activated charcoal size range was measured at 300 nm-1 micrometer. Measurement was performed using a scanning electron microscope (SEM) device. PVDF nanofiber thickness containing activated charcoal was examined with SEM and 150-500 nm fiber diameter was observed. According to filtration testing, 99.999% value was measured. Based on contact angle measurement results, 135° droplets were detected and it was determined to be superhydrophobic with super water-repellent properties. According to PVDF membrane mechanical properties, 45 MPa was measured; while with activated charcoal addition, mechanical properties improved. The highest value of 57 MPa was determined in the 8% activated charcoal-reinforced composition.

4. Conclusions

In our study, activated charcoal was successfully obtained from waste shoe insoles through pyrolysis. This ratio resulted in activated charcoal extraction of 75% from waste. Nanofiber membranes were successfully obtained using nanotechnological electrospinning technique. Useful products can be produced from waste. The aim is to produce quality products using our own domestic resources without external dependence. In our work, we chose to use waste materials that are serious problems for shoe manufacturers and the environment. Because these materials are thermoset and cannot be recycled, they do not melt and are a serious burden for the environment. They increase carbon footprint. For this purpose, we wanted to draw attention to this field and superior performance membranes that can be leak-resistant and filter were easily provided through the use of nanotechnology. There are organizations in our environment, such as shoe sole manufacturers, that significantly increase carbon footprint. With serious organization and quality project planning, waste materials can be converted to value-added products.   References [1] Akıncı, A. (1997). Structure and properties of sealing elements. [2] TOPAL, O. (2023). EMERGENCY RESPONSE APPROACHES FOR ELECTRIC AND HYBRID VEHICLES IN TURKEY. Environment City and Climate Journal, 2(3), 190-206. [3] Buluş, E., Buluş, G. S., & Yakuphanoglu, F. (2020). Production of polylactic acid-activated charcoal nanofiber membranes for COVID-19 pandemic by electrospinning technique and determination of filtration efficiency. Journal of Materials and Electronic Devices, 4(1), 21-26. [4] DOĞANCI, E., DOĞANCI, M. D., BULUŞ, G. S., & BULUŞ, E. (2023). Polylactic Acide-Activated Coal Electrospun Mat Production and Characterization. Düzce University Journal of Science and Technology, 11(3), 1365-1377. [5] Kausar, A., Ahmad, I., Aldaghri, O., Ibnaouf, K. H., & Eisa, M. H. (2023). Nanoclay-Reinforced Nanocomposite Nanofibers— Fundamentals and State-of-the-Art Developments. Minerals, 13(6), 817. [6] Kocabıyık, B. (2023). Removal of contaminants from aqueous solutions using adsorption method using activated carbon obtained from emmer (Triticum Monococcum L.) wheat husk. [7] Mohammadpourfazeli, S., Arash, S., Ansari, A., Yang, S., Mallick, K., & Bagherzadeh, R. (2023). Future prospects and recent developments of polyvinylidene fluoride (PVDF) piezoelectric polymer; fabrication methods, structure, and electro-mechanical properties. RSC advances, 13(1), 370-387.     Erdi Buluş Instructor / Material Technology Specialist Istanbul Arel University ArelPOTKAM (Polymer Technologies and Composite Application and Research Center) Transportation Services Department Civil Aviation Cabin Services Program / Vocational School   Gülseren Sakarya Buluş Expert Istanbul Provincial Health Directorate Bahçeşehir University Engineering Management Department Graduate Education Institute