Predicting bending strength of fire-retardant-treated plywood from screw-withdrawal tests
This report describes the development of a test method and predictive model to estimate the residual bending strength of fire-retardant-treated plywood roof sheathing from measurement of screw-withdrawal force. The preferred test methodology is described in detail. Models were developed to predict loss in mean and lower prediction bounds for plywood bending strength as a function of a screw-withdrawal force. Our analysis of fire-retardant-treated plywood from three different studies, each with various fire-retardant-treatment, processing, plywood thickness, and exposure temperature groupings, clearly indicated that different fire-retardant-treatments and plywood thicknesses could not be grouped into a single “universal” model. Nevertheless, some grouping was possible; parameter estimates for several grouped fire-retardant formulations and plywood thicknesses are reported for mean trends and lower prediction boundaries. Although the models were shown to acceptably predict plywood bending strength, additional work is needed to expand these models to address the effects of plywood quality, wood temperature, and moisture content at time of test.
BORLU BİLEŞİKLER VE SU İTİCİ MADDELERİN CENNET AĞACI ODUNUNUN FİZİKSEL ÖZELLİKLERİ ÜZERİNE ETKİLERİ / PHYSICAL PROPERTIES OF HEAVEN WOOD TREATED WITH BORATES AND WATER REPELLENTS
Bu calisma, cesitli borlu bilesikler ve monomer su itici maddeler (SIM)’le muamele edilen cennet agaci odununun yogunluk, yanma ve su alma gibi bazi fiziksel ozelliklerinin belirlenmesi amaclarina yonelik olarak hazirlanmistir. Calismada borlu bilesiklerden , borik asit (BA), boraks(Bx) ve borik ait ve boraks karisimi (7:3; agirlik:agirlik); monomer su itici maddelerden metilmetakrilat (MMA), Stiren (St), stiren + metilmetakrilat (7.3; hacim:hacim) ve izosiyanat (ISO) kullanilmistir. Calismada ayrica ticari emprenye maddelerinden Vacsol (V), immersol WR, polietilen glikol-400 (PEG-400), Tanalith-CBC ve fosforik asit (FA) karsilastirma amaciyla denenmistir. Deney sonuclarina gore; en yuksek ozgul agirlik degeri ISO ile muamele edilen deney orneklerinde elde edilmistir (0.80 gr/cm3). Calismada kullanilan monomer maddeler, orneklerin su alma oraninda onemli derecede azalma saglarken; borlu bilesikler uzerine uygulanan monomer muamelesi de benzer etkiyi gostermistir. Calismada stiren ve metilmetakrilat karisimi su alimini azaltan en etkili uygulama olmustur. Yanma sonucu olusan agirlik kaybi acisindan BA+Bx karisimi % 63 ‘luk agirlik kaybi orani ile en olumlu sonucu vermistir. This study was designed to investigate some physical properties of heaven wood such as specific gravity, water absorbtion levels and combustion properties treated with borates and water repellent monomers. Three different monomers such as styrene (St), methyl metacrylate (MMA) and St-MMA mixture (70:30; v:v) icocyanate (ISO) were used. Also some commercial preservatives Vacsol (V), Immersol WR, Tanalith-CBC polyethylene glycol (PEG-400) and phosphoric acid were used for comparision. Accordingto the results; wood specimens treated with ISO gave the highest specific gravity value. (0.80 gr/cm3 ). All water repellent monomer chemicals significantly reduced water absorption levels of wood specimens. Secondary treatments with monomers on borates showed same effect. Styrene and MMA mixture was the most effective in reducing water absorbtion levels of wood specimens. Borates exhibit their well known fire-retardant effect at some extent. The lowest mass losses were recorded with the specimens treated with boric acid and borax mixture (% 63).
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.