Kağıt geri dönüşüm işlemlerinin selülozun yapısında meydana getirdiği değişimler üzerine bir inceleme

Kağıt yapısının ana iskelet elemanı olan selüloz, yeryüzündeki canlı organizmalar tarafından üretilen en önemli doğal polimerlerden birisidir. Selüloz esaslı liflerin su ile etkileşimi ve bünyesine su alarak şişme, suyun uzaklaşmasıyla daralma özelliği göstermesi safiha yapısının oluşması için önemlidir. Atık kağıtların geri dönüşüm işlemleri sırasında selüloz kalıtsal olarak değişime uğramakta, suda şişme özeliği geri dönüşümsüz olarak azalmaktadır. Selüloz liflerinde meydana gelen bu değişiklik sonucu liflerin esneklik ve plastikleşme özelliği kaybolmaktadır. Selüloz liflerinin kuruması ve tekrar su ile muamelesi sonucu mikrofibrillerin yeniden karşılıklı olarak düzenlenmesi sonucu daha yoğun hidrojen bağları oluşmakta ve selülozun kristal yapısı artmaktadır. Bu durumdaki selüloz liflerinden üretilen kağıtların fiziksel ve direnç özellikleri azalmaktadır. Selülozun yapısında meydana gelen bu değişiklerin yakından incelenmesiyle, geri dönüşüm işlemlerinde bazı müdahalelerle örneğin mekanik işlemler veya kimyasal madde ilavesiyle, kalıtsal değişimler ve kalite düşmeleri belli sınırlar içersinde tutulabilir.

Anahtar Kelimeler:

büzülme, ıslatma, selüloz, kağıt, geri dönüşüm, şişme

A study on paper recycling effects on cellulose properties

Cellulose is the main structural element of paper, one of the most important natural polimers that producted by plants. The water-cellulose interactions that causing swelling with water intake or shrinkage with water removal is very key issue for formation of sheet. However, during paper recycling, cellulose is undergoes some changes and swelling properties in water decreases irreversible. As a result of these modifications, plasticity and elastic properties of fibers modified. Once dried cellulose fibers after rewetting can cause reorientation of microfibrillated structure and further hydrogen bonds formed and crystallinity is increased. Monitoring cellulose structure during recycling, some additional process such as mechanical or chemical adding, ireversible changes might be control under acceptable level.

Keywords:

shrinkage, wetting, cellulose, paper, recycling, swelling,

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