CEVİZ KABUĞU VE KAOLİN KATKILI POLİPROPİLEN KOMPOZİTLERİN TERMAL KARAKTERİZASYONU

Öz

Doğal esaslı organik ve inorganik dolgu malzemeleri için kompozit malzemeler son yıllarda dikkat çeken yenilikçi bir malzeme sınıfı haline gelmiştir. Gelişmiş mekanik özellikleri, kimyasal dirençleri ve işlenebilirlik avantajları nedeniyle geniş bir kullanım alanına sahip olan termoplastiklerin başında gelen Polipropilen (PP) polimerinin sahip olduğu özellikleri daha da iyileştirmek, petrol esaslı polimerlerin kullanım oranlarını ve çevresel etkilerini azaltmak gibi amaçlar, doğal esaslı dolgu maddelerinin kullanımlarının giderek artmasına sebep olmuştur. Bu çalışmada tarımsal bir atık olan ceviz kabuğunun (W) doğal bir kil minerali olan kaolin (K) ile birlikte PP matrisinde kullanılabilirliği incelenmiş, doğal ve inorganik iki dolgu maddesinin sinerjik etkileri termal analizler ile karakterize edilmiştir. Diferansiyel taramalı kalorimetrik analiz (DSC) sonuçları, kaolinin etkili bir çekirdeklenme ajanı olarak hareket ettiğini, PP'nin kristalleşme sıcaklığını 115,7 °C'den 122,2 °C'ye yükselttiğini ve kristallik derecesini %48,2'den %53,7'ye yükselttiğini, erime sıcaklığının ise tüm bileşimler için neredeyse sabit kaldığını (165–167 °C) ortaya koymuştur. Termogravimetrik (TGA) ve termomekanik analizler, hibrit W/K dolgulu PP kompozitlerin gelişmiş termal ve boyutsal stabilite sergilediğini, en yüksek termal bozunma başlangıç sıcaklığının 426,1 °C'ye ulaştığını ve doğrusal ısıl genleşme katsayısı (CLTE) değerlerinin 86,6 µm/m·K'ye düştüğünü göstermiştir. Bu da dolgu hibridizasyonunun termal direnç ve viskoelastik performans üzerinde sinerjik etkileri olduğunu göstermektedir. Kullanılan iki doğal esaslı dolgu malzemesinin PP ile kombinasyonunun, kompozitlerin termal özelliklerini geliştirebildiği, aynı zamanda çevre üzerindeki olumsuz etkilerini de azaltabilme potansiyeline sahip olduğu görülmüştür.

Anahtar Kelimeler

• Ceviz Kabuğu
• Kaolin
• Biyo Esaslı Polipropilen Kompozitler
• Dolgu Maddelerinin Sinerjik Etkisi
• Termal Özellikler

THERMAL CHARACTERIZATION OF WALNUT SHELL AND KAOLIN ENHANCED POLYPROPYLENE COMPOSITES

Öz

Composite materials for natural-based organic and inorganic fillers have become an innovative class of materials that have attracted attention in recent years. Improving the properties of Polypropylene (PP), which is one of the most widely used thermoplastics due to its advanced mechanical properties, chemical resistance and processability advantages, and reducing the usage rates and environmental impacts of petroleum-based polymers have led to the increasing use of natural-based fillers. In this study, the applicability of walnut shell (W), an agricultural waste, together with kaolin (K), a natural clay mineral, in PP matrix was investigated and the synergistic effects of natural and inorganic fillers were characterised by thermal analyses. Differential scanning calorimetry (DSC) results revealed that kaolin acted as an effective nucleating agent, increasing the crystallization temperature of PP from 115.7 °C to 122.2 °C and enhancing the degree of crystallinity from 48.2% to 53.7%, while the melting temperature remained nearly constant (165–167 °C) for all compositions. Thermogravimetric analysis (TGA) and thermomechanical test results showed that hybrid W/K filled PP composites exhibited improved thermal and dimensional stability, with the highest thermal onset temperature reaching 426.1 °C and reduced coefficient of linear thermal expansion (CLTE) values down to 86.6 µm/m·K, indicating synergistic effects of filler hybridization on thermal resistance and viscoelastic performance. It was observed that the combination of two natural-based fillers with PP can improve the thermal properties of the composites and also has the potential to reduce the negative impact on the environment.

Anahtar Kelimeler

• Walnut Shell
• Kaolin
• Bio-based Polypropylene Composites
• Synergistic Effect of Fillers
• Thermal Properties

Kaynakça

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