Hevea rubber market and applications

Natural rubber is a highly valuable biomaterial: in contrast with most other biopolymers it is essential for many applications and cannot be replaced by synthetic materials. For example, heavy-duty tyres for trucks, buses, and airplanes,as well as many latex products for the medical profession, cannot be made with synthetic rubber, or only at great cost. About 10% of the latex harvested from Hevea trees is manufactured into latex products. Latex films form an excellent barrier to pathogens, including viruses: condoms and gloves provide excellent protection from infection.

This is largely due to the excellent film-forming nature of natural rubber latex. In this aspect, natural rubber latex is vastly superior to vinyl films and to most other competitive materials. Natural rubber films are also very strong and are closely fitting (tactile performance is not impaired and may even be enhanced). Gloves made from this material both protect the wearer and the object (scientific samples, objects, drugs, foodstuffs, electronic components, etc) or the person being handled. The latex harvested from the tree is concentrated by centrifuging, removing some of the water and much of the proteins, and is preserved with ammonia.

Products such as gloves and condoms are produced by dipping a porcelain or glass former into the latex. Usually, the latex is prevulcanised by mixing with sulphur and accelerators. In the next steps, the coated former is dipped into a coagulant (typically calcium nitrate) to gel the latex, and then heated in a continuous oven, which dries and vulcanizes the latex films. The remaining 90 % of latex is coagulated and converted into dry rubber. Usually smallholder rubber has been coagulated prior to sale, already in the tapping cup.

The coagulated rubber is milled and washed to remove contaminants introduced by collection and transportation. Most of the natural rubber is dried by using fossil fuel, which, as a rule of thumb, consumes about a tenth of the fossil fuel required to produce synthetic rubbers. Rubber sheets can also be dried by solar heating. Most of the dry natural rubber is used in tyres, especially those, which call for high performance, notably aircraft and truck tyres (more than 70 % in the USA). The ability of natural rubber to dissipate heat makes these tyres