LEE- Polimer Bilim ve Teknolojisi-Yüksek Lisans

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http://hdl.handle.net/11527/19429

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Konu "akustik özellikler" ile LEE- Polimer Bilim ve Teknolojisi-Yüksek Lisans'a göz atma
  • Öge
    Electromagnetic shielding and acoustic properties of recycled carbon black enhanced polyurethane
    (Graduate School, 2025-01-03) Özçelik, Ethem Gökhan ; Karagöz, Bünyamin ; 515211019 ; Polymer Science and Technology
    Polyurethanes are a group of polymers with various forms, that can be easily modified according to their usage area and are widely preferred in the industry. They are materials that can meet the needs of the industry for various application areas thanks to their superior mechanical properties, insulation performance, durability, low density, and easy production capabilities. In recent years, the automotive industry has been transitioning to systems that can operate with more environmentally friendly resources, in line with the sustainability targets accepted by the world and the net zero carbon emission targets accepted by the Paris 2050 agreement. Electric vehicles are designs that most automotive companies put on their agenda and offer in the markets to achieve these determined goals. Still, like every new technology, these technologies have some points that are open to improvement. The goal of increasing the driving range of electric vehicles is one of the main issues open to development. According to research, weight reduction achieved by using materials with lower density but the same properties in cars leads to fuel savings and decreased emission values while also allowing for increased driving range. Studies indicated that every 10% weight reduction in automotive results in 7% automobile fuel savings. One of the main issues discussed is vehicles N.V.H. (Noise, Vibration, Harshness) problem. Due to the operating principles of traditional vehicles, they produce sounds at low and medium frequencies and thus dampen sounds at the same and lower frequencies coming from outside the car. Since electric vehicles do not have a sound source at these frequencies, materials with acoustic barrier properties have become very important in electric vehicle designs so that the sounds originating from the wheels and traffic coming from outside the vehicle do not disrupt the comfort of the drivers. The negative effects that arise with the electrification of vehicles are another problem that is tried to be eliminated with the right material choices. Frequencies produced by electrical devices can interfere with the frequencies of other devices and thus potentially cause loss of function in devices and pave the way for data leakage, which is one of today's biggest problems. Not only the functions of the devices but also exposure to these frequencies for a very long time affects human health physically and psychologically. While materials with electromagnetic shielding properties minimize these effects, they have become another material group used in electric vehicles. These materials eliminate negative effects by damping the frequencies produced by electronic devices, thanks to the conductive metal or carbon-based additives they contain in their structures. Generally, carbon-based additives (Carbon Fiber, Carbon Black, Graphene, Carbon Nanotube, etc.) can be preferred with polymer matrixes instead of metal additives due to their high density and dispersion problems. In this thesis, the study aims to develop a polyurethane material that can be an alternative to the problems mentioned above. The semi-integral skin of the polyurethane material creates a thick surface on the outer layer, providing the low-density material with a transmission loss feature against sound waves while also providing electromagnetic shielding properties thanks to the carbon black it contains. The carbon black used in this study was obtained from ICARBON company and was obtained by pyrolysis of end-of-life automotive tires at 550C for 2 hours under the N2 atmosphere. In the first phase of the study, the electromagnetic performances of semi-integral polyurethane materials containing 2% and 5% recycled carbon black by weight, mixed with standard type mixer, were examined and compared with semi-integral polyurethane material which has 0.5% recycled carbon black by weight which was dispersed with stator type homogenizer reaching high speeds, to understand the importance of dispersion of additives in the polymer matrix. Electromagnetic shielding properties were analyzed by the waveguide method, and by determining the S21 properties of the materials, shielding efficiency in the 12.4-18 GHz Ku band was calculated for each material group. The result pointed out that the electromagnetic properties of the material produced by stator-type homogenizer were better than the other experimental groups. In the second phase of the study, the ratio of 0.5% by weight was constant, and semi-integral polyurethane materials were mixed by stator-type homogenizer with a constant amount of conductive PANI additive with the same process parameters. DSC, TGA, FTIR, mechanical, acoustic, and electromagnetic shielding properties were compared for each sample group.