Physical, mechanical and nanostructural properties of acacia mangium wood from Sabah using xray diffraction and small-angle xray scattering methods

Tamer A. Tabet, (2008) Physical, mechanical and nanostructural properties of acacia mangium wood from Sabah using xray diffraction and small-angle xray scattering methods. PhD thesis, Universiti Malaysia Sabah.

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Abstract

The main purpose of this study is to provide the knowledge and data on the physical, mechanical and nanostructural properties of Acacia mangium wood from Sabah. A further objective was to examine the influence of microfibril angle (MFA) on strength, stiffness, tree age, the distance from pith to bark and the internal structure of the wood and to predict the perfect growth age which produces pure crystalline cellulose and more ordered. The results show that the fully grown which produce fully crystalline cellulose will denote as the optimum age (a₀) was found to be 23.45 year for the pith region, a₀ was about 23.29 year for the bark region and for the pith - bark region about 22.04 ± 0.05 year. The mean length of cellulose crystalline ranged from 3.86 Å in the 3-year-old disc to 23.43 Å in the pith region of 15-year-old disc. MFA was found to decrease whilst tree age increased for the pith and bark regions. The general trend was for the MFA to be greatest in the young wood of age 3-year-old about 26.13°, and to decrease gradually with increasing the tree age. The lowest was found in the pith region of tree at 15-year-old where the angle varied from 1.99° to 0.20°. Small-Angle x-ray scattering analysis showed that fibre length, L increased from pith to bark for wood disc of 10-year-old. An inverse relationship between surface area of the single fibre, S and the distance from pith to bark was evident in this study within a single tree of 10-year-old. It was also found that Acacia mangium wood swells and shrinks in length but at the same time swells and shrinks less in the tangential and radial directions. A strong negative linear relationship was found to exist between MFA and modulus of elasticity, MOE. This trend has also been observed between MFA and modulus of rupture, MOR. An inversely correlation was evident between glass transition, Tg and MFA in Acacia mangium wood. The regression analysis of MFA and Tg data shows that about 66.4% of the variation in Tg was explained by MFA. It was found that Acacia mangium wood of age 3 year-old has the highest relaxation length (83.33 cm) and half-thickness value (57.75 cm). Tree of 15 year-old has the least relaxation length and half-thickness of 28.65 cm and 19.85 cm respectively. Neutron transmission test showed that the actual water uptake inside the vessels and through the fibres composite is ranged from 4.445% to 6.981% after 20 hours drying under 105Cº ± 1Cº.

Item Type:Thesis (PhD)
Uncontrolled Keywords:Acacia mangium, wood, microfibril angle (MFA), crystallinity, X-Ray Diffraction (XRD)
Subjects:T Technology > TS Manufactures
Divisions:SCHOOL > School of Science and Technology
ID Code:10217
Deposited By:IR Admin
Deposited On:13 Jan 2015 11:39
Last Modified:13 Jan 2015 11:39

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