INSTITUTE OF NUCLEAR SCIENCE AND TECHNOLOGY

Background

Natural rubber (NR) latex is obtained from the tree Hevea brasiliensis. In Bangladesh there are some rubber gardens in Sylhet, Chittagong, Chittagong Hill Tracts, Modhupur zones and some other areas under Bangladesh Forest Industries Development Corporation. Besides that some Private Co. possesses few rubber gardens. Bangladesh produces a considerable amount of rubber latex. Before processing for finished products and marketing the latex, it is necessary to preserve the latex and measure its properties. Also it is needs to be concentrated because NR field latex contains 65-75% water. By concentration, the excess water as well as some parts of the non-rubber is removed. This improves the rubber properties and reduces unnecessary weight of excess water. There are several processes for concentrating field latex. Among them Centrifuge and Creaming (Chemical) methods are widely used. About 90% of total world production of latex concentrates is done by centrifuge method. Technologies of both the methods are available at NRCD.

Natural rubber (NR) latex is obtained from the tree Hevea brasiliensis. In Bangladesh there are some rubber gardens in Sylhet, Chittagong, Chittagong Hill Tracts, Modhupur zones and some other areas under Bangladesh Forest Industries Development Corporation. Besides that some Private Co. possesses few rubber gardens. Bangladesh produces a considerable amount of rubber latex. Before processing for finished products and marketing the latex, it is necessary to preserve the latex and measure its properties. Also it is needs to be concentrated because NR field latex contains 65-75% water. By concentration, the excess water as well as some parts of the non-rubber is removed. This improves the rubber properties and reduces unnecessary weight of excess water. There are several processes for concentrating field latex. Among them Centrifuge and Creaming (Chemical) methods are widely used. About 90% of total world production of latex concentrates is done by centrifuge method. Technologies of both the methods are available at NRCD.

Vulcanization: Natural rubber is a colloidal dispersion of the particles of cis-1,4-polyisoprene molecules in aqueous medium. The untreated rubber is vulnerable to oxidation and easily degradable. Vulcanization means a process of crosslinking between the chains of rubber molecules. It is done to improve its physico-chemical properties such as tensile, set and aging. Conventionally it is done by using sulfur as the vulcanizing agent with some accelerators. In the radiation vulcanization process ionizing radiation (gamma rays and electron beam) is used for crosslinking. Both the processes of vulcanization of NR latex are available at NRCD.

Hand gloves from RVNRL

Some products such as hand gloves (surgical and household), balloons, rubberized jute cloths etc. from Radiation Vulcanized Natural Rubber Latex (RVNRL) have been developed at NRCD. The rubber films (thin sheets of rubber) are tested to find out the tensile strength and other related properties. For this purpose Universal Testing Machine (UTM), Geer Aging Oven etc. are available. The following tests (with standard methods and equipment) are done at this Division:

1. Tensile stress-strain properties
2. Accelerated ageing or heat resistant test
3. Tension set at normal temperature
4. Tear strength and elongation at break
5. Swelling ratio and gel fraction

The tensile properties of other materials like plastics, fiber can also be done.