Geri dönüşümde yaş pres ve kurutmanın lif özelliklerine etkisi

Kağıt selüloz lifleri arasında hidrojen bağlarmın oluşması ile üretilir. Geri dönüşüm sırasında yaş pres ve kurutma hücre duvarlarının çökmesine ve açıklıklarının kapanmasına neden olup, hidrojen bağlarını etkilemektedir. Bu olay "Hornifikasyon" olarak adlandırılmaktadır ve selülozun kristal yapısı artmaktadır. Lifler tekrar ıslatıldığında hücre duvarlarının çökmesi ve açıklıklarının kapanmasıyla oluşan artan sayıdaki hidrojen bağları nedeniyle boşlukların tekrar açılmasını önleyerek selüloz liflerinin şişmesini engellemektedir. Bu olay lifler arasında oluşacak bağlan ve dolayısıyle kağıt direnç özelliklerini etkilemektedir. Hornifikasyon bağ yapmak için elverişli yüzey alanını azaltmakta ve kağıdın çekme, kopma, patlama, katlama dirençlerini ve yoğunluğunu düşürmektedir.

Anahtar Kelimeler:

geri dönüşüm, fiziksel özellikler, odun kusurları, odun direnci, ıslak odun, odun özellikleri

Wet press and drying effects on fiber properties during recycling

Paper is made with hydrogen bonding among cellulose fibers. Wet pressing and drying affect hydrogen bond formation during recycling and cause cell wall collapse and pore closure. This phenomena is called "Hornification" and increasing the crystal structure of cellulose. When fiber is rewetted, increased number of hydrogen bonds prevents swelling ability of the fiber. This affects the fiber-to-fiber bond formation and sheet strength. Hornification reduces the surface area of fiber for bonding and tensile, breaking, bursting, folding strength and density of the paper.

Keywords:

recycling, physical properties, wood defects, wood strength, wetwood, wood properties,

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Allan, G.G. and Ko, Y.C., 1995. The microporosity of pulp. The forces influencing the intra and inter-fiber pore structure and pore size distribution in pulp and paper. Cellulose Chem Techol., 29:479-485.

Berthold, J. and Sahnen, L., 1997. Effects of mechanical and chemical treatments on pulp pore-size distribution in wood pulps examined by inverse size exclusion chromotography. J. Pulp Paper Science, 23 (6): J245-J253.

Cao, B., Tschirner, U., and Ramaswamy, S., 1999. A study of changes in wet fiber flexibility and surface condition of recycled fibers. Paperi Ja Puu, 81(2): 117-122.

Carlsson, G. and Lindström, T., 1984. Hornifıcation of cellulosic fibers during wet pressing. Svensk Papperstidning, 15: R115-R125.

Çıldır, H., and Howarth, P., 1972. The effect of reuse on paper strength. Paper Technology, (October): T149-T151.

Ellis, R. L. and Sedlachek, K. M., 1993. Recycled Versus Virgin Fiber Characteristic: A Comparison. In: Secondary Fiber Recycling. (Spangenberg, R.J., ed.), Tappi Press. Atlanta, Georgia.

Fahmy, Y. And Mobarek, F., 1971. On fine structure of cellulose fibers. Svensk Papperstidning, (Jan 15) No. 1: 2-9.

Gürkan, K., 2001. Atık kağıdın önemi ve geri kazanılması. SEKA Kağıtçılık Dergisi, (Kasım) 70:10-11.

Higgins H.G. and Me Kenzie, A.W., 1963. The structure and properties of strength. Appita, 16(6): 145-161.

Horn, R.A., 1975. What are the effects of recycling on fiber and paper properties? Paper Trade J., (Feb 17-24): 78-82.

Howard, R.C., 1990. The effects of recycling on paper quality. J. Pulp Paper Science, 16(9): J143-J149.

Hult, E.-L., Larsson, P.T., and iversen, T., 2001. Cellulose fibril aggregation-an inherent property of kraft pulps. Polymer, 42: 3309-3314.

Klungness, J.H. and Caulfıeld, D.F., 1982. Mechanism effecting fiber bonding during drying and aging of pulps. Tappi J., 65(12): 94-97.

Laivins, G.V. and Scallan, A.M., 1993. The mechanism of hornification of wood pulps. In: Products of Papermaking, C.F. Baker (Ed.), Tenth Fundamental Research Symposium, Pira International, Oxford. (Sep.): 1235-1260.

Lyne, L.M. and Gallay, W., 1950. The effect of drying and heating on the swelling of cellulose fibers and paper strength. Tappi J., 33(9): 429-435.

Maloney T.C., Li, T.Q., Weise, U., and Paulopuro, H., 1997. Intra and mter-fîbre pore closure in wet pressing. Appita, 50(4): 301-306.

McKee, R., 1971. Effect of repulping on sheet properties and fiber characteristics. Paper Trade J., (May 24): 34-40.

Metin, A., 2002. Türkiye selüloz ve kağıt endüstrisinin 2000 yılı genel durumu. SEKA Kağıtçılık Dergisi, (Ocak) 71:14-17.

Minor, J.L., 1994. Hornification- its origin and meaning. Progress in Paper Recycling, (February): 93-95.

Oksanen, T., Buchert, J., and Viikari, L., 1997. The role of hemicelluloses in the hornification of bleached kraft pulps. Holzforschung, 51(4): 355-360.

Oye, R., Okayama, T., Yamazaki, Y., and Yoshinaga, N., 1991. Changes of pulp fiber cell wall by recycling. 1st Research Forum on Recycling the Wasting, Harbor Castle Hotel, Toronto, Ontario, (Oct): 191-195.

Scallan, A.M., 1974. The structure of the cell wall of wood- a consequence of anisotropic mter-microfibrillar bonding? Wood Science, 6(3): 266-271.

Sjöström, E., 1993. Wood Chemistry Fundamentals and Applications. 2nd Edition, Academic Press, San Diego, CA.

Stamm, A.J., 1950. Bound water and hydration. Tappi J., 33(9): 435-439.

Thode, E.F., Chase, A.J., Majmudar, S.S., and Mackinnon, D.R., 1953. Dye adsorption on wood Pulp III. effect of pulp processing on specific adsorption. Tappi J., 36(11): 498-504.

Van Wyk, W. and Gerischer, G., 1982. The influence of recycling on the strength properties of machine made paper. Paperi Ja Puu, 9:526-533.

Weise, U., 1998. Hornification-mechanisms and terminology. Paperi Ja Puu, 80(2): 110-115.