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Physical, Mechanical and Seasoning Properties of Bangladeshi Rubber Wood (hevea Brasiliensis)

M. A. Sattar
Divisonal Officer (Ex)
Seasoning and Timber Physics Division, Bangladesh Forest Research Institute, Chittagong-4000, Bangladesh.

M. F. Kabir
Research Officer
Seasoning and Timber Physics Division, Bangladesh Forest Research Institute, Chittagong-4000, Bangladesh.

D.K. Bhattacharjee
Research Assistant
Seasoning and Timber Physics Division, Bangladesh Forest Research Institute, Chittagong-4000, Bangladesh.

S. B. Sarker
Senior Research Officer
Seasoning and Timber Physics Division, Bangladesh Forest Research Institute, Chittagong-4000, Bangladesh.

Abstract/ Executive Summary:

The physical, mechanical and seasoning properties of rubber wood (Hevea brasiliensis) have been studied following standard methods. It is a medium dense timber possessing lower volumetric shrinkage. It can be seasoned well with minimum defect by applying an appropriate stacking method. It takes 6 and 57 days to kiln dry and air dry of 2.5 cm planks respectively. Rubber wood is moderately strong exhibiting higher values than those of teak in most of the cases.

Keywords: Physical, Mechanical,Seasoning, Properties, Hevea brasiliensis, Volumetric shrinkage.

Location:

Start Date: 00-00-0000

End Date: 00-00-0000

Program Area: Postharvest and Agro-processing

Commodity: Rubber wood

Objectives:

Rubber trees will become over mature in 30 to 35 years of age after which the trees will cease their economic production of latex. The trees will then need to be felled for use as timber. To find the properties of over matured trees for its proper use.

Methodology:

Physical and seasoning properties: Five representative rubber trees of about 21 years of age were procured from Dantmara Rubber Plantation of BFIDC, Chittagong. The height and girth of the bolt were found to be 2.1 to 3.5 m and 0.93 to 1.52 m respectively. Two discs were taken from each bolt for preparing specimens for physical properties, viz., specific gravity and shrinkage. Twenty planks of 2.5 cm ´ 5 cm ´ 2.0 m dimensions were prepared from the logs for air drying and kiln drying purposes. Immediately after sawing planks were sprayed with prophylactic preventive treatment with sodium pentachloride preservative since rubber wood was found to be very much susceptible to fungus and borer attack. The initial moisture content (mc) of each sample board was determined by cutting moisture sections. The boards were end-coated and their initial weights were taken. The air drying samples were stacked in an open shed on 2.5 cm ´ 3.7 cm stickers in the months of June, July and August which constitute rainy season in Bangladesh. A heavy weight was placed on the top of the air drying stack as a restraint to prevent defect like distortion. Kiln drying was accomplished in a conventional steam heated drier using a kiln drying schedule developed by BFRI. Periodic weight was taken for air drying and daily weight was recorded for kiln drying in order to ascertain the progress of drying. Kiln drying was continued till the samples reached the 12% mc level. Air drying was continued till the samples reached the equilibrium moisture content (emc) prevalent in the rainy season. At the conclusion of drying the final mc was determined following usual standard procedures.

Mechanical Properties: From each tree 2.4 m bolt was cut from the butt, middle, and top trunk. Two paired sticks of 7 cm ´ 7 cm were prepared totaling 36 sticks. One pair of sticks was kept under wet condition and the other pair was airdried to about 12% moisture content. All the sticks were dressed to 5.08 cm strips and clear specimens were prepared from these strips according to the sizes specified by the ASTM standards. The specimens were tested in accordance with the specifications of ASTM. Except for toughness, all other mechanical tests were carried out in a Riehle screw power type universal testing machine. Toughness tests were performed in a toughness testing machine designed by the US Forest Products Laboratory, Madison.

Source of Information: Bulletin 13, Timber Physics Series, Bangladesh Forest Research Institute, Chittagong. 8 pp. 1992

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The following conclusions can be made from the study :

Rubber wood is a medium dense timber. Its specific gravity is slightly less than that of teak. It exhibits lower radial, tangential and volumetric shrinkage.Rubber wood can be seasoned well with care in both air and kiln drying method. The air drying timber, however, needs to be treated with prophylactic preservative to protect from blue stain and borer attack.Rubber wood is moderately stronger. Most of the mechanical properties have lower values than those of teak in green condition, but except bending and compressive strength, these were found higher in airdry condition.

Knowledge Management: Report/Proceedings