Uses, Tapping and Processing of Rubber Latex in Nigeria
Hevae brasiliensis (rubber) is the chief producer of latex among all other latex producing crops used in the plastic Industry .
The following are the uses of rubber according to its products;
- Rubber latex: This is the most important product of the rubber tree which is obtained by tapping the bark of the stem. Over 55,000 useful products are made from rubber latex. About 70-8o% of the total rubber latex is used in the manufacture of tyres, tubes and other items associated with automotive transport, 5% for the manufacture of foot-wears adhesives and 4% for cable Moreover articles such as rubberized fabrics, shock absorbers, washers and gaskets, transmission and conveyor belts, sport goods, household and hospital supplies, contraceptives, appliances, etc, are made from rubber latex.
- Rubber seeds: They serve as in time of famine by some people including the non-western Amazon who eat the rubber ceremonially. Though toxic because of the cyame poisons, the poison can be removed through soaking in water or by boiling.
- Rubber oil: The oil extracted from the rubber seeds through boiling for a long time can be used for illumination and can be purified for the manufacture of soap and other products. The residue after the oil have been extracted can be used as livestock feed but before this, the cyame poisons must be properly removed.
- The stems: When cut down the stems serve as firewood because of their excellent ability burn.
The process of collecting rubber latex is called tapping. A diagonal cut is made about 60cm above the ground on the bark of the tree with a tapping knife. The latex is collected with a cup below. Tapping is done early in the morning between 7.00am to 10.00am and for every 2-3 days. The latex from all the cups are collected together from all the rubber trees in the evening. Tools and materials used in tapping include; tapping knife, spout, collecting cup, cup hanger, collecting buckets, churns, collecting tanks, and coagulants(examples sodium sulphate) or ammonia.
Rubber processing involves four steps; (1) Mastication, when the elastomeric is sheared and the molecules are broken down for easy flow, (2) Mixing, usually carried out immediately after mastication, when additives are incorporated, (3) Shaping, the viscous mass are shaped for example by extrusion or molding and (4) curing when the polymer molecules become interlinked and the shape is fixed.
PROCESS OF TAPPING RUBBER
When the bark of Hevea brasiliensis is partially cut through, a milky substance comes out from the wound and dries to yield a rubbery film. The biological function of this latex is still obscue. It may help in wound healing by protecting the inner bark, or it may serve other biochemical functions. The latex consist of an aqueous suspension of small particles, about 0.5mm in diameter, of cis-poly soprene, a linear rubber polymer of high molecular weight .The rubber rubber content of the suspension is about 30%.The trees are tapped about every two days, yielding a cupful of latex, containing approximately 50g of solid rubber, each time.The standard method of tapping is to score three with a knife for half the circumference of the trunk, slanting the cut down from left to right at the angle of 30 degree starting at the highest point convenient for the tapper. Each subsequent cut is made below its predecessor. Trees are often rested for a period after a heavy tapping. Production begins when the tree is about 5-6 years and with care, the tree’s useful life may extend more than 20 years. With trees cultivated at a density of 375/ha, approximately 2,500kg of rubber can be produced/ha/year
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