Poliamid-6 ile yüzeyi kaplanmış kenevir lifi takviyeli poliüretan kompozitlerin özelliklerinin araştırılması
Küçük Resim Yok
Tarih
2025
Yazarlar
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Cilt Başlığı
Yayıncı
Bursa Teknik Üniversitesi
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Kompozitlerin darbe dayanımı, ozona dayanımı, korozyona dayanımı, termal iletkenliği, tasarım esnekliği, hafifliği ve üretim çeşitliliği potansiyeli gibi ayırt edici özellikleri tüm sektörlerde kullanımını günden güne arttırmaktadır. Kompozit ailesinin en fazla tercih edileni polimer matrisli kompozitler; havacılık ve uzay sanayii, otomotiv sektörü, inşaat ve altyapı sektörü, savunma sanayi, spor ekipmanları ev elektrik-elektronik sektöründe kullanılmaktadır. Polimer matrisli kompozitlerde takviye fazında doğal ve sentetik lifler tercih edilmekte ancak küresel ısınma, daha düşük karbon ayak izi, biyobozunurluk, düşük maliyet, iyi mekanik ve yalıtım özellikleri gibi parametreler sonucu son yıllarda doğal lifler üzerindeki çalışmalar artış göstermektedir. Bu çalışmada Poliüretan (PU) matris, çeşitli kullanım alanına ve üretim şekline sahip olmasının yanı sıra kimysallara dayanımı ve iyi mekanik özellikleri sebebiyle kullanılmıştır. Takviye fazında ise kenevir lifi hafifliği, yüksek mukavemet özelliği, tamamen doğada çözünebilir oluşu, düşük maliyetli üretimi sebebiyle tercih edilmiş; yüzeyi PA 6 kaplanarak matrise tutunması, su emme özelliği ve termal kararlılığı iyileştirilmiştir. Kompozit üretiminden önce kenevir liflerinin kaplama işlemi araştırılmıştır. SEM, FTIR, DSC ve TGA analizleri ile kaplama işleminin yüzeyi uygun şekilde kapladığı, liflerin yüzeylerinin düzleştiği ve termal olarak daha kararlı hale geldikleri görülmüştür. Yapılan çekme testi ile 1 mm çapında nozül kullanılan kaplama işleminin yüzeyde %137 kaplama birikmesine neden olduğu, kenevire oranla çekme mukavemetinin %12 - kopma uzamasının %42 düştüğü, elastik modülün ise %43 arttığı tespit edilmiştir. Kompozit üretiminde bu değerlere sahip lifler kalıba elle yatırılarak üzerine PU karışımı dökülmüştür. Karşılaştırmalar PU, Kenevir/PU ve PA 6-Kenevir/PU üzerinden yürütülmüştür. SEM analizi sonucunda kompozitlerin gözenekliliğinin PU'ya göre arttığı belirlenmiş olup kaplanan kenevir kullanımının daha az gözenekli yapı oluşturduğu görülmüştür. Yoğunluk değerleri PU için 1,070 g/cm3, Kenevir/PU için 0,855 g/cm3 ve PA 6-Kenevir/PU için 0,948 g/cm3 şeklinde bulunmuştur. Su absorpsiyonu testi sonucunda değerler PU %0,4, Kenevir/PU %1,85, PA 6-Kenevir/PU %1,65 şeklinde bulunmuştur. Oluşan gözenekli yapının getirisi olarak yoğunluğun düşmesi ve su absorpsiyonunun artması deneysel verilerle uyuşmaktadır. Uygulanan çekme testi sonucunda en yüksek mukavemet değeri 23,4 MPa ile PA 6-Kenevir/PU numunesinde, kopma uzaması %4,2 ile PU numunesinde, elastik modül ise 1057,2 MPa ile PA 6-Kenevir/PU numunesinde ölçülmüştür. 3-nokta eğme testinde maksimum gerilme 47,1 MPa ile PU numunesinde, maksimum uzama %6,5 ile PU numunesinde, elastik modül ise 1250,7 MPa ile PA 6-Kenevir/PU numunesinde ölçülmüştür. Mekanik testlerin gerilim-gerinim grafikleri incelendiğinde PA 6-Kenevir/PU kompozitinin sert yapıda olduğu görülmüştür. Elde edilen tüm sonuçlar ışığında daha hafif, daha sert, deforme olması zor olan ancak su emme potansiyeli yüksek kompozitlerin elde edilmesi; kullanım alanı olarak mobilya destek ünitesi, taşımada titreşim önleyici birimler ve spor ekipmanı iç destek dolgusu şeklinde değerlendirilebilir. Anahtar kelimeler: Kenevir, Lignoselülozik kompozit malzemeler, Poliüretan, Kompozit
The distinctive properties of composites, such as impact resistance, ozone resistance, corrosion resistance, thermal conductivity, design flexibility, lightness and production diversity potential, are increasing their use in all sectors day by day. The most widely used type of composite is polymer matrix composites, which are employed in the aerospace industry, automotive sector, construction and infrastructure sector, defence industry, sports equipment, and electrical and electronic sectors. In polymer matrix composites, both natural and synthetic fibres are preferred as reinforcing phases; however, due to parameters such as global warming, lower carbon footprint, biodegradability, low cost, and good mechanical and insulation properties, research on natural fibres has increased in recent years. In this study, polyurethane (PU) matrix was used due to its resistance to chemicals and good mechanical properties, as well as its various applications and production methods. In the reinforcement phase, hemp fibre was chosen for its lightness, high strength, complete biodegradability, and low-cost production; its surface was coated with PA 6 to improve adhesion to the matrix, water absorption, and thermal stability. The coating process of hemp fibres was investigated prior to composite production. SEM, FTIR, DSC, and TGA analyses revealed that the coating process adequately covered the surface, flattened the fibre surfaces, and made them thermally more stable. Tensile tests revealed that the coating process using a 1 mm nozzle resulted in a 137% increase in surface coating, a 12% decrease in tensile strength and a 42% decrease in elongation at break compared to hemp, while the elastic modulus increased by 43%. In composite production, fibres with these values were manually placed in the mould and PU mixture was poured over them. Comparisons were made between PU, Hemp/PU and PA 6-Hemp/PU. SEM analysis revealed that the porosity of the composites increased compared to PU, and that the use of coated hemp resulted in a less porous structure. The density values were found to be 1.070 g/cm³ for PU, 0.855 g/cm³ for Hemp/PU, and 0.948 g/cm³ for PA 6-Hemp/PU. The water absorption test results were 0.4% for PU, 1.85% for hemp/PU, and 1.65% for PA 6-hemp/PU. The decrease in density and increase in water absorption due to the porous structure are consistent with the experimental data. As a result of the tensile test applied, the highest strength value was measured at 23.4 MPa in the PA 6-Hemp/PU sample, the elongation at break was 4.2% in the PU sample, and the elastic modulus was 1057.2 MPa in the PA 6-Hemp/PU sample. In the three-point bending test, the maximum stress was 47.1 MPa in the PU sample, the maximum elongation was 6.5% in the PU sample, and the elastic modulus was 1250.7 MPa in the PA 6-Hemp/PU sample. When examining the stress-strain graphs of the mechanical tests, it was observed that the PA 6-Hemp/PU composite has a rigid structure. In view of all the results obtained, it is possible to produce composites that are lighter, harder, more resistant to deformation, but with high water absorption potential. These composites can be used in furniture support units, vibration-preventing units in transportation, and internal support fillings in sports equipment. Keywords: Hemp, Lignocellulosic composite materials, Polyurethane, Composite
The distinctive properties of composites, such as impact resistance, ozone resistance, corrosion resistance, thermal conductivity, design flexibility, lightness and production diversity potential, are increasing their use in all sectors day by day. The most widely used type of composite is polymer matrix composites, which are employed in the aerospace industry, automotive sector, construction and infrastructure sector, defence industry, sports equipment, and electrical and electronic sectors. In polymer matrix composites, both natural and synthetic fibres are preferred as reinforcing phases; however, due to parameters such as global warming, lower carbon footprint, biodegradability, low cost, and good mechanical and insulation properties, research on natural fibres has increased in recent years. In this study, polyurethane (PU) matrix was used due to its resistance to chemicals and good mechanical properties, as well as its various applications and production methods. In the reinforcement phase, hemp fibre was chosen for its lightness, high strength, complete biodegradability, and low-cost production; its surface was coated with PA 6 to improve adhesion to the matrix, water absorption, and thermal stability. The coating process of hemp fibres was investigated prior to composite production. SEM, FTIR, DSC, and TGA analyses revealed that the coating process adequately covered the surface, flattened the fibre surfaces, and made them thermally more stable. Tensile tests revealed that the coating process using a 1 mm nozzle resulted in a 137% increase in surface coating, a 12% decrease in tensile strength and a 42% decrease in elongation at break compared to hemp, while the elastic modulus increased by 43%. In composite production, fibres with these values were manually placed in the mould and PU mixture was poured over them. Comparisons were made between PU, Hemp/PU and PA 6-Hemp/PU. SEM analysis revealed that the porosity of the composites increased compared to PU, and that the use of coated hemp resulted in a less porous structure. The density values were found to be 1.070 g/cm³ for PU, 0.855 g/cm³ for Hemp/PU, and 0.948 g/cm³ for PA 6-Hemp/PU. The water absorption test results were 0.4% for PU, 1.85% for hemp/PU, and 1.65% for PA 6-hemp/PU. The decrease in density and increase in water absorption due to the porous structure are consistent with the experimental data. As a result of the tensile test applied, the highest strength value was measured at 23.4 MPa in the PA 6-Hemp/PU sample, the elongation at break was 4.2% in the PU sample, and the elastic modulus was 1057.2 MPa in the PA 6-Hemp/PU sample. In the three-point bending test, the maximum stress was 47.1 MPa in the PU sample, the maximum elongation was 6.5% in the PU sample, and the elastic modulus was 1250.7 MPa in the PA 6-Hemp/PU sample. When examining the stress-strain graphs of the mechanical tests, it was observed that the PA 6-Hemp/PU composite has a rigid structure. In view of all the results obtained, it is possible to produce composites that are lighter, harder, more resistant to deformation, but with high water absorption potential. These composites can be used in furniture support units, vibration-preventing units in transportation, and internal support fillings in sports equipment. Keywords: Hemp, Lignocellulosic composite materials, Polyurethane, Composite
Açıklama
21.02.2026 tarihine kadar kullanımı yazar tarafından kısıtlanmıştır.
Anahtar Kelimeler
Polimer Bilim ve Teknolojisi, Polymer Science and Technology
