Bambusa vulgaris Schrad, a village bamboo cultivated in all parts of Peninsular Malaysia, was tested for the manufacture of low and medium density urea particle boards. The study indicates that the urea particewle board must have a minimum density of 600 kg/m3 and 8 per cent resin content to meet the requirements of Type 1 Board, Standard Board and British Standards.
However, urea particle boards with density around 600 kg/m3 and 10 per cent resin content exhibited excellent strength and dimensional properties. Equal amounts of flakes of Bambusa vulgaris Schrad, and other cellulosic materials could also be used to manufacture urea particle boards that meet the requirements of the Standards Board, British Standards.
In Peninsular Malaysia, fifty species of bamboo are available twenty-five of which are indigenous. Bambusa vulgaris Scharad (buluh gading) is the most common Malaysian village bamboo. It is a perennial woody grass, belonging to the family Gramineae and to the sub-family Bambusoidac, Watson & Wyatt Smith, 1961. Malaysia has a long tradition in the use of bamboo.
There are about 104 factories making bamboo products like skewers, blinds, chopsticks and tooth picks. The processing of these products generates waste in the range of 28 to 47%. These wastes could be a ready source of ligno-cellulosic material for the manufacture of urea particle boards (UF-boards).
Experimental Procedure for Producing Bambusa Vulgaris Schrad:
Thirty two culms of B. vulgaris were collected from a riverside in Kampung Benus, Bentong, Pahang Darul Makmur. The average length, diameter, and wall thickness of the culms were 7.5 m, 7 cm and 1 cm respectively. Culms with the nodes removed were then chipped by a Taihei chipper. Flaking of B. vulgaris, Yemane, rubber- wood and Acacia mangium by a Pallmann knife ring flaker in FRIM made chips of dimension 3×2 cm x 6 mm.
The cutting knives were set to produce 0.6 mm thick flakes which were of suitable dimensions for board making and required no further processing. The flakes were dried to less than 5% moisture content (m.c.) before screening to separate the fines.
It was not possible to flake oil palm stems by the Pallmann knife ring flaker as clusters of fibrous materials that were produced became entangled between the knives and the scoring blades of the flaker causing the flaker to jam and the whole process to stop. Instead the oil palm stems were initially sliced into discs of about 3 cm thick before being oven dried at 150°C for 2 or 3 days to prevent fungal attack.
The discs were then processed into chips of dimensions 3×3 cm x 5 mm and hammer milled into particles in a Scott-Rietz disintegrator. The particles were sieved to separate the fines. Flake samples of industrial wood wastes were obtained from an industrial particle board mill in Pahang.
Measured quantities of flakes and fines for the production of 19 mm UF-boards of varying densities and resin contents were sprayed in a Drais mixer with a resin mix containing urea formaldehyde, hardener and water. The sprayed particles and fines with a controlled m.c. of 12% were laid in a mould and pre-pressed at 3.5 kg/m3.
The consolidated mat was finally pressed to the required thickness at 160°C for 6 minutes. Three boards were made for each condition.
The UF boards from admixtures of equal parts by weight of B. vulgaris and particles of other common wood species were manufactured with a resin content of 8% and calculated density of 700 kg/m3. The pressing time and temperature was 6 minutes and 160 degrees C respectively. The UF-boards were assessed according to the British Standards BS 5669, Anonymous (1979).
Results and Discussions Related to Bambusa Vulgaris Schrad:
Yemane and A. mangium are species planted under the Compensatory Forest Plantation Programme (CFPP) and have average wood density below 450 kg/m3 and maximum bulk density of 70 g/l for their particles. The density of oil palm stems ranges between 200 and 600 kg/m3. Particleboard trails of species of low densities (450 kg/m3 and below) gave blowing problems. Moslemi (1974) attributed these problems to the interaction between mat moisture content and board and particle density during hot pressing.
The quantity particles in a certain volume of particles mat would increase with a decrease in the specific gravity of the raw material resulting in smaller openings for the steam flow within the particle mat during hot press. Consequently, the steam pressure within the board increases as steam is not sufficiently vented for the board to prevent blowing. Hence, it was not possible to produce UF boards of Yemane and A. mangium of density 650 kg/m3 and above. However, board making trails of admixtures of B. vulgaris and these CFPP species did not give any problems for UF boards of density more than 650 kg/m3.
UF-boards of densities above 600 kg/m3 and resin contents of 6-10% met the bending strength (MOR) requirements of Type 1 Board as specified in the British Standards. For the internal bond (IB) requirement, a minimum resin content of 8% and density of 600 kg/m3 was necessary; with a higher density of 700 kg/m3, a lower resin content of 6% could satisfy the IB of the British Standards. Increased resin content and board density considerably improved all the strength properties of the UF boards. All the UF boards satisfied the screw withdrawal requirements and had thickness swellings well below the stipulated maximum rate of 12% in the British Standards.
The properties of UF boards, manufactured from the different species and the admixtures comprising equal parts by weight of the species and B. vulgaris particles revealed, it was not possible to produce UF boards of density 650 kg/m3 and above from the CFPP species, UF-boards were successfully manufactured from the admixtures comprising B. vulgaris and the CFPP species.
In fact, the IB of these boards was much higher than the IB obtained for UF boards of B. vulgaris, Yemane or A. mangium. UF-boards from oil palm stems and industrial wood wastes could hardly meet the specifications of the British Standards as their MOR values were below the minimum 13.8 MPa stipulated but UF boards from the admixtures of the species with S. vulgaris had MOR values above 13.8 MPa.
All the UF-boards from the admixtures of B. vulgaris and the wood species satisfied the screw withdrawal requirements and had thickness swellings below the maximum 12% allowed for Standard Board, stipulated in the British Standards.
Conclusion:
B. vulgaris is a potential source of raw material for the manufacture of UF boards. The UF boards of density 700 kg/m3 and 8% resin content from this species and admixtures in equal parts by weight with oil palm stems and industrial wood wastes could fulfill the requirements of Type 1 Board, Standard Board stipulated in the British Standards.
This enhanced the possibility of using the oil palm stems and industrial wood wastes for the commercial manufacture of medium density UF boards. In addition, particles of B. vulgaris blended well with particles from the CFPP species, viz., Yemane and A. mangium, of low wood density to produce higher density UF-boards with acceptable properties.