The Experimental Investigation of The Recycling Effect on The Low Strain Rate Behavior of HDPE and PP Materials Under Tensile Loading

Öz

Thermoplastics are widely used as engineering materials due to their advantages such as lightweight, corrosion resistance, and low cost. However, thermoplastic waste stands out as one of the major contributors to environmental pollution. This situation not only presents an economic disadvantage but also reduces the quality of life. The recyclability of thermoplastic materials is a crucial feature to address these disadvantages. Recycling not only conserves raw materials but also reduces environmental pollution. However, changes in the molecular structure of thermoplastics during the recycling process can lead to degradation in their rheological and mechanical properties. In this project, The impact of recycling via extrusion on tensile strength and the elasticity modulus of High-Density Polyethylene (HDPE) and Polypropylene (PP) materials at different strain rates was investigated. The raw HDPE material was recycled once and thrice, while the raw PP material was recycled once. The results indicated that the mechanical properties of HDPE material remain largely unaffected even after three recycling processes, while the PP material shows a slight reduction in elasticity after one recycling process. Additionally, an increase in mechanical properties was observed for all material types at high strain rates. While this increase was nearly the same for both raw and recycled HDPE materials, recycled PP materials exhibited a higher increase in mechanical properties compared to raw PP material. The results suggest that HDPE and PP materials subjected to a limited number of recycling processes can still be used as engineering materials.

Anahtar Kelimeler

• Recycling
• HDPE
• PP
• Strain Rate Behavior
• Mechanical Characterization

Geri Dönüştürmenin HDPE ve PP Malzemelerinin Düşük Gerinme Hızı Altındaki Mekanik Davranışlarına Olan Etkisinin Deneysel Olarak İncelenmesi

Öz

Termoplastikler hafiflik, korozyona dayanıklılık ve düşük maliyetli olmaları gibi avantajları sayesinde yaygın bir şekilde mühendislik malzemesi olarak kullanılmaktadır. Ancak, termoplastik atıklar çevre kirliliğindeki en önemli sebeplerden bir tanesi olarak göze çarpmaktadır. Bu durum ekonomik olarak bir dezavantaj oluştururken hayat kalitesini de düşürmektedir. Termoplastik malzemelerin geri dönüştürülme kabiliyeti bu dezavantajları elimine etmek için çok önemli bir özelliktir. Geri dönüştürme yöntemi ile bir yandan hammadde tasarrufu sağlanırken bir yandan da çevre kirliliği azaltılmaktadır. Ancak, geri dönüştürme işlemi sırasında termoplastik malzemelerin moleküler yapısında meydana gelen değişiklikler reolojik ve mekanik özelliklerinde bozunmalara yol açabilmektedir. Bu projede ekstrüzyon ile geri dönüştürme işleminin Yüksek Yoğunluklu Polietilen (HDPE) ve Polietilen (PP) malzemelerinin farklı gerinim hızlarındaki çekme mukavemetine ve elastisite modülüne etkisi incelenmiştir. Ham HDPE malzemesi bir ve üç defa ekstrüzyona tabi tutularak, ham PP malzemesi ise bir defa ekstrüzyona tabi tutularak geri dönüştürme işlemi gerçekleştirilmiştir. Elde edilen sonuçlar HDPE malzemesinin üç defa geri dönüştürülse bile mekanik özelliklerini kaybetmediğini ancak PP malzemesinin bir defa geri dönüştürme sonucunda az da olsa elastikiyetini kaybettiği göstermiştir. Ayrıca, yüksek gerinim hızlarında tüm malzeme tiplerinin mekanik özelliklerinde bir artış olduğu görülmüştür. Bu artış oranı ham HDPE ve geri dönüştürülmüş HDPE malzemeleri için hemen hemen aynı seviyede iken geri dönüştürülmüş PP malzemelerinin yüksek gerinim hızlarındaki mekanik özelliklerindeki artış oranı ham PP malzemesine göre daha yüksek seviyede meydana gelmiştir. Sonuçlar, az sayıda geri dönüştürme işlemine maruz kalmış HDPE ve PP malzemelerinin mühendislik malzemesi olarak kullanılabileceğini göstermektedir.

Anahtar Kelimeler

• Geri Dönüşüm
• HDPE; PP
• Gerinim Hızı Davranışı
• Mekanik Karakterizasyon

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