MEDIUM DENSITY FIBERBOARD (MDF) MANUFACTURING FROM WHEAT STRAW (Triticum aestivum L.) AND STRAW WOOD MIXTURE

In this study wheat straw was taken from Ankara province. In order to produce dry process MDF, urea formaldehyde resin was used at the ratio of 8 %, 10 % and 12 %, 1 % ammonium chloride was used as hardening agent on the basis of dry fiber weight. On the other hand, 5, 6 and 7 min. pressing times were applied. Alcohol benzene, cold water, hot water and 1 % NaOH solubility of wheat straw were 5.15 %, 7.31 %, 9.84 % and 40.79 % respectively. In addition, holocellulose, cellulose, lignin and ash contents were found as 74.79 %, 52.67 %, 20.17% and 4.21 % respectively. Optimum fiber morphology values were as follow; fiber length 1.2-1.5 mm, fiber width 12-16 µm, lumen diameter 4-6 µm and double wall thickness 7.5 -11.5 µm Optimum fiber production conditions for MDF manufacturing were as follows; Vapor pressure : 10.5 atm, steaming time : 4 minutes, defibration time : 2 minutes. 0.700 g/cm 3 , 0.800 g/cm 3 density straw MDF boards and 0.800 g/cm 3 density wood fiber MDF boards were manufactured. On the other hand, 0.800 g/cm 3 straw-wood fiber mixture MDF boards were produced at the rates of 70% -30%, 50%-50% and 30%-70%. Modulus of rupture (MOR), modulus of elasticity (MOE), internal bonding (IB), thickness swelling and water absorption of the boards were measured. After the evaluations of the results obtained, optimum straw MDF boards manufacturing conditions were as follows; Adhesive ratio : 12 %, pressing time : 6 minutes, press temperature : 150 °C, pressure : 200-220 kp/cm 2 , hardening agent : 1 % and straw - wood ratio 50 %- 50 %.

BUÐDAY SAPLARINDAN (Triticum aestivum L.) VE SAMAN-ODUN KARIÞIMI LÝFLERDEN ORTA YOÐUNLUKTA LÝF LEVHA (MDF) ÜRETÝMÝ

Bu çalýþmada, hammadde olarak Ankara ilinden temin edilen buðday (Triticum aestivum L.) saplarý kullanýlmýþtýr. Kuru yöntemle MDF üretiminde % 8, 10 ve 12 oranýnda üre formaldehit tutkalý yapýþtýrýcý, sulu amonyum klorürün % 30’luk çözeltisinden % 1 oranýnda sertleþtirici olarak kullanýlmýþtýr. Ayrýca, 5, 6 ve 7 dk’lýk presleme süreleri denenmiþtir. Buðday saplarýnýn alkol-benzen, soðuk su, sýcak su ve % 1’lik NaOH çözünürlüðü sýrasýyla; % 5.15, % 7.31, % 9.84 ve % 40.79 olarak bulunmuþtur. Ayrýca, holoselüloz, selüloz, lignin ve kül miktarlarý sýrasýyla; % 74.79, % 52.67, % 20.17 ve % 4.21 olarak belirlenmiþtir. Yapýlan lif morfolojisiyle ilgili çalýþmalarda kullanýlan buðday saplarýnýn lif uzunluðu 1.2-1.5 mm, lif geniþliði 12-16 µm, lümen çapý 4-6 µm ve çift çeper kalýnlýðý 7.5-11.5 µm bulunmuþtur. Buðday saplarýndan MDF eldesi için en uygun lif üretim þartlarý; buhar basýncý 10.5 atm, buharlama süresi 4 dk ve liflendirme süresi 2 dk olarak belirlenmiþ ve uygulanmýþtýr. Saman liflerinden 0.700 g/cm 3 ve 0.800 g/cm 3 , odun ve saman-odun karýþýmý (% 30 saman + % 70 odun, % 50 saman + % 50 odun, % 70 saman + % 30 odun) liflerden ise 0.800 g/cm 3 özgül kütleli MDF levhalarý üretilmiþtir. Tüm levhalarýn elastikiyet modülü, eðilme direnci, yüzeye dik çekme direnci ile 24 saatteki su alma ve kalýnlýðýna þiþme deðerleri belirlenmiþtir. Laboratuar koþullarýnda elde edilen MDF levhalarýn fiziksel ve mekanik özellikleri üzerinde yapýlan deðerlendirmeler sonucunda buðday saplarýndan en uygun MDF üretim koþullarý; tutkal miktarý % 12, pres süresi 6 dakika, pres sýcaklýðý 150 °C, pres basýncý 200-220 kp/cm 2 , sertleþtirici miktarý % 1 ve saman/odun oraný % 50 -% 50 þeklinde belirlenmiþtir.