AÇIK HAVA KOŞULLARININ ODUN DAYANIMINA ETKİSİ

Yıl 2005, Cilt: 7 Sayı: 8, 72 - 79, 01.06.2005

Hikmet Yazıcı

Öz

Herhangi bir koruyucu kullanmadan, uygun tür seçilmeden kullanılan ağaç malzemenin fiziki ve ekonomik ömrü sınırlıdır. Ağaç malzemenin çeşitli teknikler yardımıyla koruyucu kimyasal maddelerle muamele edilerek kullanım süresinin uzatılması ve niteliklerinin iyileştirilmesi ise önemli bir gelişmedir. Açık hava etkisi ise çoğunlukla rutubet etkileri ve sıcaklık değişmelerinden kaynaklanan fiziksel olaylarla, fotokimyasal reaksiyonları kapsayan uzun süreli karmaşık bir süreçtir. Açık hava şartlarında kullanılacak ahşap malzemenin türünün, direnç özelliklerinin değişiminin, dayanım süresinin ve maruz kalınan zararlı faktörlerin bilinmesi

gerekmektedir. Ahşap malzemenin açık hava şartlarında bozunma ve tahrip olması organik ve inorganik olmaktadır. Organik faktörler çürüme, küf, bakteri ve böcekleri, inorganik faktörler ise güneş, rüzgar, su, bazı kimyasallar ve ateşi kapsamaktadır. Odun üzerinde oluşacak çeşitli enerji formlarının nispi etkilerinde de farklı ağaç türleri itibarıyla değişim görülmektedir. Odundaki kimyasal değişmeler, renk değişmeleri, mikroskobik değişmeler, fiziksel değişmeler ve biyolojik faktörlerin sebep olduğu değişmeler belirli zaman faktörü sonunda oluşmaktadır. Boya, yüzey işlem maddeleri ve derine nüfus eden koruyucu maddeler odunu uzun süreli korumakta ve dış mekanlarda uygun şartlar da dayanım sürelerini arttırmaktadır. Açık hava etkisine karşı korunma çalışmaların da en iyi korumayı boyanın sağladığı, en az korumanın transparan verniklerden sağlandığı belirtilmektedir.

Anahtar Kelimeler

Açık Hava Koşulları, Yıkanma, Boyalar, Yüzey İşlemleri

THE EFFECTS OF WEATHERİNG ON WOOD STRENGTH

Öz

The use of wooden materials without preservatives and improper selection of the species shorten their service life. It is such an important development that impregnation of wooden materials using various techniques with preservatives helps extending service life and increasing the quality. Weathering is such a long and complicated process that includes physical changes along with moisture and change of temperature and photochemical reactions. It is necessary to investigate the characteristics of wooden materials used outdoors such as species, change of strength, service life and exposure to harmful factors. Destruction of wooden materials used outdoors can be the result of either organic or inorganic factors. Organic factors are fungi, mould and mildew, bacteria and insects. Inorganic factors are sunlight, wind, water, various chemicals and fire. Variation of destruction caused by the factors mentioned above differs from wood species. Chemical, microscopic, and physical changes, coloration and discoloration, caused by biological factors happen after certain periods of time. Paints, wood finishes and preservatives protect wood for a very long time and prolong their service life. According to studies, the highest protection can be achieved by using paints and the lowest is by transparent varnishes.

Anahtar Kelimeler

The Effects of Weathering, Paints, Leaching, Finishing

Kaynakça

• Arnold, M.; Sell, J.; Feist, W., C., 1991, “Wood weathering in fluorescent ultraviolet and xenon arc chambers”, Forest Product Journal, 41(2): 40 – 44.
• Arnold, M.; Feist, W. C.; Williams, R., S., 1992, “Effect of Weathering of New Wood on the Subsequent Performans of Semitransparent Strains”, Forest product J., 42 – 3; 10 – 14.
• Carll, C., G.; Feist, W., C., 1994, “Long-term weathering of finished aspen wafer board”, Forest Product Journal, 39(10): 25-30.
• Feist, W. C., 1984, “Weathering interactions on treated untreated wood surfaces”, Wood Product Convention, 13-23.
• Feist, W. C., Hon, D., N-S., 1984, “Chemistry of Weathering and Protection”, İn Rowell, R., M., “The Chemistry of Solid Wood”, Advances in Chemistry Series, 207, Washington D. C., 1984: Chapter 11.
• Carll, C., G.; Feist, W., C., 1994, “Weathering and Decay of Finished Aspen Wafer board”, Forest Product Journal, 37(4): 27-30.
• Feist, W. C., Rowell, R., M.; Ellis, W. D., 1989, “Moisture Sorption and Accelerate Weathering of Acetylated and Methacrylated Aspen”, Wood and Fiber Science, 23(1): 128-136.
• Feist, W. C., 1990, “Outdoor Wood Weathering and Protection”, Forest Product Journals, 263-298.
• Feist W., C., 1990, “Weathering Performans of Painted wood pretreated with water-repellent Preservatives”, Forest Product Journals, 40(718): 21-26.
• Horn, B., Qıu, J., Owen, N., L., Feist, W., C., 1992, “FT-IR Studies Of Weathering Effects İn Western Red Cedar and Southern Pine”, Forest Product Journal, 176: 67-76.
• Kalnins, M., Feist, W. C., 1993, “Increase in Wettability Of Wood with Weathering”, Forest Product Journal, 43(2): 55 – 57.
• Sandberg, D., 1992, “Weathering of Radial and Tangential Wood Surfaces Of Pine and Spruce”, holzforschung, 53: 355 – 364.
• Williams, S., R., Plantinga, P., L., Feist, W., C., 1990, “Photo degradation of wood affects paints adhesion”, Forest Product Journal, 40(1): 45-49.
• Denez, A., R., Young, R., A., 1999, “Reduction of Weathering Degradation of Wood through Plazma-PolymerCoating”, Holzforschung, 53,632-640.
• Anderson, E., L., Powlak, Z., Owen, N., L., Feist, W., C., 1991, “Infrared Studies Of Wood Weathering”, Forest Products J, 45, 4,641-647.
• Falk, R., H., Felton, C., Lundin, T., 1996,”Effects Of Weathering On COLOR Loss Of Natural Fiber Thermoplastic Composites”, Natural Polymers and Composites, USA, Wisconsin 382-387.
• Falk, R., H., Lundin, T., Felton, C., 1994,”The Effects of Weathering on WOOD Thermoplastic Composites Intended FOR Outdoor Applications”, Forest Products journals. USA Medicon, 175-179.
• Williams, S., R Feist, W., C., 1994,”Effect Of Preweathering Surface Roughness and Wood Species On The Performance Of Paint and Stains”, USDA Forest Products J, 66-828..
• Feist, W., C., 1994,”Weatnering Performance of Finished Aspen Siding”, Forest Products J, 44-6:15-23.
• Kopf, F., W., Sell, J.; Feist, W., C., 1994, “Comparative Weathering Tests Of North American and European Exterior Wood Finishes”, Forest Products J, 44-10:33-41.
• Stark, N., M., Matuana, L., M., Clemans, C., M., 2004,”Effect Of Processing Method On Surfaces and Weathering Characteristics Of Wood-Flour /HDPE Composite” Journal at Applied Polymer Sciences, 33:1021-1030.
• Stark, N., M., Matuana, L., M., 2003, “Surface Chemistry Changes Of Weathered HDPE/Wood-Flour Composites Studied by XPS and FTIR Spectroscopy”, Polymer Degradation and Stability; Elsevier, 86:1-9.
• Halmes, C., A., Knispel, R., D., 1981,”Exterior Weathering Durability of Some Leach-Resistant Fire-Retardant Treatments for Wood Shingles: A Five-year Report “, Forest Products Laboratory, Research PoperFPL 403, Medicon, USA.
• Owen,J., A., Owen, N., L., Feist, W., C., 1993,”Scanning Electron Microscope and Infrared Studies Of Weathering in Southern Pine “Journal Of Molecular Stucture,300:105-114.
• Williams, S., R Feist, W., C., 1993,”Durability of Paint or Solid-Color Stain Applied to Preweathered Wood”, Forest Product J. 48(1), 8-14.
• Feist, W. C.; 1992, '' Natural Weathering of Wood and Its Control by Water–Repellent Preservatives'', American Painting Contractor, Vol. 69, No. 4. pp, 18-21.
• Wilkinson, J.G., Industrial Timber Preservation, Associated Business Press, London, 1979.
• Bozkurt, A.Y., Göker, Y., Erdin, N., Emprenye Tekniği, İ.Ü. Orman Fakültesi Yayınları No 3279/425, İstanbul, 1993
• Hafızoğlu, H., Yalınkılıç, M.K., Yıldız, Ü.C., Bayındırlık ve İskan Bakanlığı Yüksek Fen Kurulu Başkanlığına gönderilen 03.09.1991 tarihli rapor.
• Rowell, R.M., Treatments that enhance physical properties of wood, U.S. Dept. of Agriculture, Forest Service, Forest Products Laboratory, General Technical Report FPL-50, 1987.