Evaluation Of Tropical Wood (Sawdust) Its Engineering Properties And Particle Size:- Okocha, Tobechukwu V

ABSTRACTS ix Physical properties ofsawdust (i.e. particle size distribution, particle density, porosity, and water retention) from five tropical commercial wood species (Shorea leprosula, Dryobalanops lanceolata, Dipterocarpus cornutus, Shorea laevis, and Eusideroxylon zwageri) as prepared in various mill types (i.e. handsaw, sawmill, and milling) were analyzed. This study aims to look into the relationship and interconnected between the use ofdifferentmill types, density ofwood species origin and physical properties of the resulting sawdust. Generally, different mill types produced sawdust with different particle size distributions. The use of a handsaw produced a higher proportion of oversized particles (OS) and coarser particle size (CPS) than that of sawmill and milling, while also commonly producing the lowest proportion offine particle size (FPS). For each wood species, the proportion of OS was lower than that of CPS and FPS. In addition, particle density and water retention produced by handsaw in CPS as well as FPS wasthe smallest, followed in an increasing order sawmill and milling. Porosity ofCPS and FPS was the highest in handsawcut sawdust, followed in a decreasing order sawmill and milling cut sawdust. This study showed that the different mill types and particle size influenced the physical properties ofsawdust. Further, analysis ofinfluential factors on porosity and water retention using General Linear Model revealed that particle density inflicted a strong influence on porosity, as did particle size on water retention. The average ofparticle size distribution with ± standard deviation (SD) combined for all sawdust samples from five different wood densities showed that particle size distribution ofCPS produced by handsaw was 60.4 + 2.6%, which was the highest, followed in a decreasing order by sawmill (52.6 + 1.5%) and by milling (25.6 + 2.1%). Consequently, this pattern affects the proportion of particle size in other classes, e.g. FPS. The proportion ofparticle size distribution in FPS produced by handsaw was the smallest (30.0 + 1.2%), followed in an increasing order by sawmill (37.2 + 1.3%) and by milling (71.8 + 1.9%). Keywords: physical properties, sawdust, wood species origin, CPS, OS, FPS.