Suitability of Yushania Alpina for Oriented Particleboard
Highland bamboo (Yushania alpina) and lowland bamboo (Oxytenanthera abyssinica) are widespread in Ethiopian. Both covering approximately 1 million hectare of land. No commercial importance has been found for these lignocellulose materials. It is thus the main objective of this study is to determi...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2005
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/52/1/1000548923_t_Fh_2005_7.pdf |
| Summary: | Highland bamboo (Yushania alpina) and lowland bamboo (Oxytenanthera abyssinica)
are widespread in Ethiopian. Both covering approximately 1 million hectare of land. No
commercial importance has been found for these lignocellulose materials. It is thus the
main objective of this study is to determine the suitability of Yushania alpina for the
manufacture of oriented particleboard.
Yushania alpina from three major bamboo growing areas, namely Ambo, Bore and
Masha of three age groups of bamboo (one, two and three year-old) were used for this
study. The effects of bamboo growing sites and age variation on mensurational attributes
(i.e., culm basal diameter, culm wall thickness, culm volume and weight) and on basic
properties (i.e., moisture content, density, anatomical characteristics, buffering capacity
and wettability of bamboo) were statistically analyzed using completely randomized
design. The analysis indicated that mensurational attributes and basic properties of vary
with respect to growing sites, ages and culm height.
Homogenous, three-layered oriented from fine particle sizes, three-layer oriented from
coarse particle sizes and three-layered oriented conventional (a mixture of fine and
coarse particles) bamboo particleboards were manufactured using 10% ureaformaldehyde
resin to evaluate the effects of particleboard processing parameters such as
board density, particle size, particle orientation and particle layering on mechanical
properties and dimensional stability. The completely randomized design with factorial
experiments was used in the analysis.
The results show that the mechanical properties and dimensional stability of homogenous
boards made from three-year old bamboo varied among the growing sites. Age of
bamboo did not show significant effects on strength and stiffness properties of
homogenous bamboo particleboards. It was also found that the internal bond strength of
bamboo particleboards decreased as the bamboo gets older whilst thickness swelling
increased.
The modulus of rupture (MOR) and modulus of elasticity (MOE) of three-layered
oriented bamboo particleboards produced from fine particle sizes and three-layered
oriented bamboo particleboards produced from coarse particles were significantly
affected by particle alignment and sizes. Both types of particleboards made from fine and
coarse particle sizes and parallelly aligned to the longitudinal axis of the boards had
superior strength (about 15%) compared to random oriented boards. Similar
comparisons of the MOE between oriented and random boards showed that MOE of
parallelly aligned boards to the longitudinal axis of the boards was higher by 28% and
37%, respectively for both fine and coarse particle size oriented boards than those of
random boards. The internal bond strength, thickness swelling and water absorption of
oriented bamboo particleboards showed insignificant variation with particle alignment.
However, boards made from fine particle sizes gave 35% higher IB strength and 12%
dimensionally stable oriented boards than those made from coarse particle. The screw
withdrawal resistances of oriented bamboo particleboards were affected by particle
alignment and particle size. Boards made from coarse particles that were randomly
oriented particles had superior screw withdrawal resistance than that made from fine
particles.
The properties of three-layered conventional oriented bamboo particleboards were
affected by the density profile of the boards. As fine particles at face layer was increased
from 20% to 30% (based on the weight of the board) the MOR and MOE of the boards
increased from 27 MPa to 41 MPa and 4.9 GPa to 6.1 GPa, respectively. The thickness
swelling (TS) decreased from 7.5 to 5.8 % and the internal bond (IB) strength increased
from 0.60 MPa to 0.69 MPa. The presence of high amount of fine particle at the face
layers and high internal bond strength increased significantly screw withdrawal
resistance.
In general, vertical density profile has significant impact on strength and stiffness
properties of three-layered boards. Three-layered boards that have steeper density
gradient (higher average face layer density and low core density) have high strength and
stiffness properties than three-layered boards which have relatively more uniform density
profile. Regression equations of three-layered boards relating the proportion of fine
particles on the face layer to coarse particles in the core layer may be used to predict the
MOR, MOE, IB strength and TS of three-layered particleboards produced in this study.
Generally, the strength and dimensional stability of particleboards manufactured from
Yushania alpina bamboo met the ISO standards ISO/DIS 16978, ISO/DIS 16984 and
ISO/DIS 16983 for high performance general purpose particleboards |
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